Open Mind

Uncertain Sensitivity

October 27, 2007 · 159 Comments

There are numerous feedbacks in the climate system, and the feedbacks which affect global temperature are overwhelmingly positive. One example is water vapor feedback: increased temperature leads to greater absolute humidity in the atmosphere, and water vapor is a potent greenhouse gas, so this further increases warming. Another is ice albedo feedback: warmer conditions reduce snow and ice cover, which are highly reflective of incoming sunlight; when snow and ice are replaced with open land and ocean (which are far less reflective), earth’s albedo decreases, so the planet absorbs a greater fraction of incoming sunlight and again we experience further warming.


Suppose warming of amount 1 deg.C leads to a further warming of f deg.C; we can call f the feedback factor. Then we expect this additional warming of f also to trigger the feedback mechanism, so we’ll see yet more warming, in the amount f \times f = f^2. This additional warming also triggers the feedback mechanism, causing yet more warming in the amount f \times f \times f = f^3, and so on and so on, etc., etc. The total warming is therefore

\Delta T = 1 + f + f^2 + f^3 + ... = 1/(1-f).

Thus if the basic feedback factor is f, then the total increase due to feedback will be different. We can call this the gain due to feedback, so

G = 1/(1-f).

If there were no feedbacks in the climate, then we can estimate climate sensitivity with considerable precision: each increase in climate forcing of 1 W/m^2 (watt per square meter) would lead to temperature increase of between 0.3 and 0.31 deg.C. Another way to state climate sensitivity is that doubling CO2 concentration leads to an increase in climate forcing of about 4 W/m^2, so would lead to about 1.2 deg.C temperature increase. We can call this the no-feedback climate sensitivity to doubling CO2, or we can just call it S_0. With feedbacks, this change will be multiplied by the gain factor G, so the actual climate sensitivity to doubling CO2 will be S = GS_0.

A recent post on RealClimate discusses a new paper by Roe and Baker about why estimates of the probability distribution for climate sensitivity are so asymmetric; they have a long “tail” at the high end with small but not insignificant probabilities for very high values, but almost no probability of very low values. The fundamental reason is that we don’t really estimate the total feedback, i.e., the gain, G, what we really estimate is the feedback factor f.

Suppose we know the probability distribution for the feedback factor f. This is a function P_f(f) such that the probability that f lies in a small interval of width df, centered on the value f, is

Prob. = P_f(f) ~df.

What will be the probability distribution for the gain factor? It’s straightforward to compute that if we know the probability distribution P_f(f) for one variable (in this case, f), we can compute the probability distribution P_G(G) for another variable (in this case, G) which is simply a transform of the original variable:

P_G(G) = P_f(f) / [dG/df],

where dG/df is the derivative of G with respect to f. Since we know that in this case G=1/(1-f), we get

P_G = P_f(f) / (1-f)^2 = G^2 P_f.

There are two important consequences of this. One is that if the probability distribution for f is symmetric, like for example the normal distribution, then the probability distribution for G will not be. In fact it will have a long tail on the high end, with small but not insignificant probability of very high values, but almost no chance of very low values. Another is that if the probable accuracty of our estimated feedback factor f is \sigma_f, then the probable accuracy of our estimated gain factor G will be greatly magnified, approximately given by

\sigma_G = G^2 \sigma_f.

An example may clarify. Suppose the probability distribution for f is approximately the normal distribution, with mean value \bar f=0.7 and standard deviation \sigma_f=0.14. Then the probability distribution for G looks like this:

probg.jpg

It follows that the probability distribution for climate sensitivity looks just like it (after all, S is just a multiple of G):

probs.jpg

In this graph I’ve added dashed lines indicating the usual range of likely values quoted in the press, from about 2 to 5 deg.C per doubling CO2. There’s a striking difference between the tails of this distribution; the high end shows nontrivial likelihood extending even to very high values, while on the low end the probability quickly drops to near zero. There’s another difference too: the “spread” of the probability distribution, which is the basic uncertainty in our estimate of G, is much greater than the spread in our distribution of f. For this case, the uncertainty 0.14 in f translates to uncertainty of approximately 1.6 in G, and that translates to uncertainty of about 1.9 deg.C in climate sentivity S.

It’s in the nature of things that methods of estimating feedback actually amount to estimating the feedback factor f. The gain G and sensitivity S are then derived from this. It’s also in the nature of things that probability distributions which emerge from our estimates of f are roughly normal. Hence the probability distributions for G and S will always have a bigger, longer tail at the high end, and much more uncertainty, than the distribution for f. Even if we can estimate the feedback factor f with reasonably good precision so \sigma_f is low, the precision in S will be not so good.

Roe and Baker’s analysis has implications for policy choices, above and beyond its scientific interest. It has been suggested that it’s not really a good idea to set a “hard target” for limiting CO2 concentration (such as the sometimes-suggested 450 ppmv), because if sensitivity turns out to be substantially greater than 3 deg.C (an oft-quoted average value) then that goal won’t be good enough to avoid extremely dangerous climate change. Instead targets should be flexible, so that if sensitivity turns out to be higher than expected we can adjust the target to keep climate change in the less-dangerous range. However, we’re rapidly approaching the point at which it will be no longer realistic to aim for such targets. CO2 levels currently are about 382 ppmv, and rising at about 2.1 ppmv/yr, which if sustained will bring us to the 450 ppmv level right around the year 2040 (perhaps in my lifetime). And since CO2 emissions are increasing, and there are signs that the ability of oceans and biosphere to absorb part of the increased CO2 from human emissions, this would seem to be an optimistic forecast.

It also should be taken as a stern warning. It really is possible, even if unlikely, that climate sensitivity is on the high end of estimated ranges, or higher. If that’s true then we’re headed for real trouble. For me, this emphasizes the urgency of the problem. It’s not something to leave for the next generation, or even the next decade. We need strong action to limit tampering with the climate, and we need it now.

Categories: Global Warming · climate change

159 responses so far ↓

  • NeuvoLiberal // October 27, 2007 at 4:53 pm

    Interesting observation, Tamino.

    From my non-expert point of view, it seems to me that the presence of water on earth makes our system less sensitive than say Venus. Increased temperature seems to make for greater precipitation and that’s a negative feedback.

    However, the net feedback appears to be positive and that seems to be the nature of the system at the current state.

    Case in point being, I found it interesting that while Arctic sea ice is setting records for minimum extent (and maybe area as well. Is it?), Antarctic sea ice seems to have set record for maximum area, but with the net sea ice area dropping fairly rapidly and especially so since circa 2000 AD.

    It’s like we are rapidly melting out ice and snow in NH and sending that partly to the sea as water, partly to become new ice in SH, and some into the atmosphere as water vapor. That’s the big picture I am seeing in terms of water cycle modulation underway.

    Regarding your formulation here, the question is, of course, what the value f approximately is. If f is say 0.1, then the asymptotic sensitivity ΔT = 1/0.9 ≅ 0.111. Another question here is the what the time-constant for this temperature auto-sensitivity could be estimated to be.

    [Response: Actually 1/0.9 = 1.111..., and that's the gain, not the sentivity; you multiply that by the no-feedback sensitivity 1.2 to get about 1.3.

    I'm not sure, but I think the announcement of a new record maximum in southern hemisphere sea ice was preliminary, and has since been retracted. Even if not, the announced new record was only 0.9% above the previous record, whereas the northern hemisphere minimum broke the old record by 27%.

    Different feedbacks have different timescales. Water vapor feedback is practically instantenous. Ice-albedo feedback is both short and long; it's fast for reduction in snow cover but it's slower for ice wasting. CO2 feedback is slow because of the long mixing time for the deep ocean, but might end up being faster than that if melting permafrost releases significant CO2.]

  • Hank Roberts // October 27, 2007 at 7:14 pm

    The important consequence that I haven’t seen documented yet is that the winter sea ice accumulates algae that drops into the ocean when the ice melts.

    The rate at which food becomes available is going to change as melting happens faster. The total amount of food will change if the total amount of ice surface (at least) starts to decline.

  • Leif Svalgaard // October 27, 2007 at 7:18 pm

    tamino: “We need strong action to limit tampering with the climate, and we need it now.”

    Isn’t cutting CO2 tampering with the climate?

    [Response: Is this an attempt to be provocative? Do you disagree that putting an end to fossil-fuel CO2 *emission* represents *stopping* interference with climate?]

  • Leif Svalgaard // October 27, 2007 at 7:48 pm

    “Is this an attempt to be provocative? Do you disagree that putting an end to fossil-fuel CO2 *emission* represents *stopping* interference with climate?”

    if we found a method to take CO2 OUT of the atmosphere [iron seeding, algae blooms, what not - who knows what future capabilities we'll have] there might people or groups that would like to induce global cooling or undo the warming that has happened [which was "bad" in some people's eyes]. So, putting an end to CO2 emissions does not represent stopping interference, only that particular kind of interference. I never intend to be provocative.

    [Response: Such efforts fall under the umbrella-term "geoengineering." I'm highly skeptical of our ability to anticipate the consequences; it could lead to very unpleasant unexpected side effects. For the health of the planet, I think it's a better idea to "quit smoking."

    But many have explored geoengineering strategies. The method "du jour" seems to be injecting sulfate aerosols into the stratosphere; there's a post about that on RealClimate.]

  • cody // October 27, 2007 at 8:46 pm

    Isn’t the non-feedback CO2 relationship complicated by what levels the doubling starts at?

    I thought that the effect of increased CO2 is not linear, but decays logarithmically. So if we double from present levels, it will not have the same effect as doubling from an hypothetical 191ppm to get to present levels? Or put it another way, the next 10 ppm will be less effective in warming than the previous 10.

    Somewhere I’ve seen charts of the decreasing efficacy of rising CO2 levels but don’t any longer recall where.

  • NU // October 27, 2007 at 8:52 pm

    “It’s also in the nature of things that probability distributions which emerge from our estimates of f are roughly normal.”

    What is the justification for that statement?

    We don’t measure f directly; we infer it from observations of temperature and other physical quantities. I might buy that temperature measurements have normal errors, but if the feedback factor is not related linearly to observed temperature (and I don’t think it is), it will have a non-normal error. (Things are more complicated when you consider multiple observational constraints.)

    The Roe and Baker analysis just seems to beg the question, shifting the question of the long tail of climate sensitivity onto the normality of the feedback factor.

    I will agree that any transient observations over a period much less than the equilibration time will make it hard to rule out large climate sensitivities, since over a sufficiently small time they will have an observational signature similar to more mainstream sensitivity values.

    But the devil is in the details: the real question is even if there is some kind of asymmetric tail, how much can we shrink the tail by including more kinds of data, and how much benefit will we get from that? Annan and Hargreaves have already argued that we can shrink it enough to be policy relevant. I don’t see R&B’s qualitative analysis as really addressing that question.

    [Response: Feedback factors can be estimated from theoretical physics, and from climate model simulations. Water vapor feedback, for instance, can be computed from physical principles based on the assumption that with rising temperatures, *relative* humidity remains roughly constant (an assumption with a solid physical basis and observational support). Ice albedo feedback can be computed if we know the changes in ice and snow, which we can estimate from both observations and model simulations (we've only recently become aware that estimates of the rate of ice loss are too low, which bodes ill for the climate). We can then compute the climate *forcing* from these changes in water vapor, snow/ice, etc., in W/m^2, and use that to compute the feedback factor f. The feedback factors of all the various feedback mechanisms are additive, to give the total feedback factor.

    Model simulations end up doing the same thing. Multiple runs amount to a large number of experiments, usually with a variety of parameter values (to explore parameter space), and the multiplicity of parameter choices and physical processes amount to a large number of factors which *accumulate* to determine the feedback factor f, because *the physics is in the feedback factor, not the final sensitivity*. That's why, as Roe and Baker show, the probability distribution functions estimated from ensemble runs of model simulations are reasonably well approximated by a normal distribution for f -- but definitely NOT for S.

    Because the feedback factor is the *accumulation* of many physical mechanisms (both for theoretical and model-based estimates), we can apply the *central limit theorem* -- that its probability distribution will be assymptotically normal. It's not perfectly normal, only approximately so; but the distribution for sensitivity is nowhere near normal.

    Annan and Hargreaves make a strong case that sensitivity lies in the IPCC range, from 2 to 4.5 deg.C.]

  • Heretic // October 27, 2007 at 9:08 pm

    I find your reflexion a little puzzling, Dr. Svalgaard. Extracting carbon that has been stored in the crust for tens or hundreds of millions of years and injecting it in the atmosphere is, so far, the largest direct climate interference ever realized.

    Perhaps you’d argue that land use/characteristics (the only comparable magnitude change coming to mind) are as much of an interference, which is debatable.

    In any case, you may not agree that the consequences of the current uncontrolled carbon experiment are “bad” but you can not show either that they are “good.”

    Another point: “who knows what future capabilitites we’ll have?”
    Indeed, nobody really knows, but some are nevertheless intent on betting that these yet unknown capabilities could be apt at solving planetary scale problems. I remain skeptical.

  • NU // October 27, 2007 at 11:00 pm

    Tamino,

    As I alluded to earlier, I could equally well apply the central limit theorem to temperature observations, claim that they have a normal distribution, and demonstrate that the feedback parameter can’t (since the two are related nonlinearly).

    In fact, you can’t apply the CLT to prove that the feedback factor should be normally distributed. The CLT applies to the sum of identically distributed random variables. If I say that the total feedback is the sum of many different feedbacks, f = f1 + f2 + f3 + …, then I can only apply the CLT if the means of f1, f2, f3, … are the same. (Also their variances, and in general they have to come from identical distributions.) That is, we need to f1 = f2 = f3 = … (or rather E(f1) = E(f2) = E(f3) = …) in order to conclude that f is normally distributed. But of course this is not true, since the fi are different feedbacks, not merely multiple estimates of the same feedback.

    Look at it this way: we know what happens to the temperature response in an ideal CO2-doubling experiment: it rises at some rate determined by the transient dynamics, and after a long time asymptotes to a value equal to the equilibrium climate sensitivity. If the ECS equals, say, 3 degrees, we can certainly rule out, say, 10 degrees with high probability if we wait long enough: just keep measuring temperatures until they visibly approach an asymptotic value.

    This requires making observations after a period of time comparable to the equilibration time, but it’s possible in principle, and is a counterexample to the idea that ECS will always have a long tail.

    The reason why it does still have a long tail now is because we haven’t been able to make measurements for such a long time.

    However, by combining extended observation periods (instrumental + paleoclimate), or by combining shorter-term but complementary observations (e.g., surface temperature + ocean heat uptake), we can hope to effectively reproduce such a long period of measurement, and cut off the tail.

    As you note, Annan and Hargreaves make a case that paleoclimate can exclude a lot of the ECS > 4.5 C probability mass; others have shown that ocean heat uptake as an additional constraint can cut off a chunk of the tail too (Tomassini et al. this year in J. Climate is the most recent example I can think of).

    In summary, the extent to which you can cut off the long tail of ECS is still an open question, Roe and Baker’s analysis notwithstanding.

    [Response: Only the most crude formulation of the central limit theorem applies exclusively to identically distributed variables. I have shown this myself in the peer-reviewed literature. As long as the variance is not dominated by a small number of variables with far greater variance than the others, it still applies. And the fact that the variables have different mean values is completely irrelevant.

    And you *cannot* apply the central limit theorem to sensitivity (which is the real issue), because sensitivities are nowhere near additive. Feedback factors, and the physical processes which determine them, are at least approximately so.]

  • peterhearnden // October 28, 2007 at 8:04 am

    Dr Leif Svalgaad said

    “Isn’t cutting CO2 tampering with the climate?”

    What about adding CO2 to the atmosphere? Is that tampering?

    Surely reducing Co2 back to where it was before we started adding it (and started tampering with the atmosphere) is to simply do that - to remove our tampering.

    Dr Svalgaard, I’ve seen versions of your argument before - I simply don’t get where you are coming from.

  • cody // October 28, 2007 at 8:40 am

    tamino, is it true that 75% of any possible temperature increase from CO2 doubling has already taken place, because of the decreasing sensitivity of the atmosphere to each extra increment of CO2? I finally tracked down a source of this assertion, and it was attributed to a paper by Pielke which is no longer available online.

    But is this right? And if it is, then why is there all the emphasis on stopping further rises, which would seem not to be capable of having very grave effects?

  • Leif Svalgaard // October 28, 2007 at 2:14 pm

    peterhearnden: “Surely reducing Co2 back to where it was before we started adding it (and started tampering with the atmosphere) is to simply do that - to remove our tampering.”

    Tampering is a negative word, as if we were doing something wrong. Now, if we could all the CO2 we have produced since the little ice age [LIA] back in the ground, we would presumably return to LIA conditions and miserable climate. This does not seem to be something desirable [just ask wheat growers in Canada and Russia]. So rather than ‘tampering’ it would seem to me that what we have been doing is ‘ameliorating’ the climate. And a far as I’m concerned, we could use some more of that. I would consider returning to the LIA as tampering. So, now we seem to have two camps: A) the return-to-LIA fanatics and B) the bring-on-the-warmth fanatics. I’m in camp B and perhaps you are in camp A. Maybe there is a camp C: I-don’t-want-any-change. Camp C is not realistic because climate changes all the time, some natural, some not, and the question [to me, at least] is how we and our political institutions best deal with such change.

  • S2 // October 28, 2007 at 3:36 pm

    Thanks, Tamino, for another instructive post - I certainly understand more than I did before I read it.

  • ks // October 28, 2007 at 6:30 pm

    “They stated that cold can be just as dangerous as heat, if not more so. While that is true in an abstract sense, it is hardly a reason to be complacent about climate change. Furthermore, it illustrates a fundamental lack of understanding of the problem.

    Climate change is more than global warming. Seeing it in that way is an unfortunate consequence of being hobbled by one-dimensional thinking (hot vs. cold). If the temperature would merely change, up or down, with all other parameters remaining the same, we could deal with that. But dealing with increased climate variability is a much more difficult problem. Gerberding and Boxer pointed this out. Unfortunately, people who have one-dimensional thought processes don’t grasp this concept. “

  • Hank Roberts // October 28, 2007 at 8:10 pm

    http://www.pnas.org/cgi/content/abstract/104/37/14580
    http://adsabs.harvard.edu/abs/2007GeoRL..3405607C
    http://www.pacificscience.org/tfoceanacidification.html
    http://co2.cms.udel.edu/Ocean_Acidification.htm

    Warm hell.

  • William Connolley // October 28, 2007 at 9:31 pm

    Did you notice that the R+B formulation gives a finite probability of f > 1?

  • Leif Svalgaard // October 29, 2007 at 12:30 am

    ks: “But dealing with increased climate variability is a much more difficult problem.”

    I’m not sure if you mean “weather” variability. Climate being defined as average over decades (used to be 30 years) would not vary much on top of the change due to a steady increase of CO2. So I’ll assume “weather”, like hurricanes, storms, etc. The atmosphere is a heat engine. The work you can get out of a heat engine does not depend on the mean temperature, but on the temperature difference. Since the high and mid-latitudes seem to heat up more than the tropics [the latter being good at shedding the heat by shoving it to higher latitudes.

    global warming might mean a smaller latitude gradient of temperature and thus a smaller difference and less work out of the engine, thus less weather variability. I’m sure this is well-trodden ground and that y’all heard all this before and that it does not matter what I say, but do allow this old 1D person to present his views. But do tell me were I go wrong, when and if. And do try to keep it civil.

  • cce // October 29, 2007 at 5:22 am

    Eyeballing a chart from AR4, CO2 in the LIA (270 ppm) and the MWP (280 ppm) was separated by about 10 ppm, and we are currently about 100 ppm higher than during the MWP. Assuming we could put the CO2 back, the idea that it would result in “LIA conditions” is a bit of a stretch. Instead, why don’t we try to limit warming to 2 degrees, thus keeping the climate within a range relevent to human beings.

  • CraigM // October 29, 2007 at 12:58 pm

    leif/dr svalgaard

    “So, now we seem to have two camps: A) the return-to-LIA fanatics and B) the bring-on-the-warmth fanatics. I’m in camp B and perhaps you are in camp A. Maybe there is a camp C: I-don’t-want-any-change. “

    Well, i might be in another camp; maybe camp D. Im like, lets not go back to another major ice age or a LIA (wasnt that caused more by a reduction in solar ouput?). And we might have discovered a way of doing that: simply add c02 to the atmosphere.

    And if we are to warm this sucker up, lets like, maybe, have a go slow policy in place and figure out what might actually happen before we rush gun-ho into a possible 5 oC warming in just the next 100 years. Yknow, maybe stretch things out over a few 100 to 100o years. Just so we can get our adaptation policies in place. That way us Australians and Africans might have more time to get sorted out. And Denmark and Norway, or whoever owns greenland, will be happy also (its a shame the polar bear is gunna get shafted though. Such a beautiful animal). So, i guess, Im in the ‘lets have slow change rather than quick change’ camp.

  • Leif Svalgaard // October 29, 2007 at 1:57 pm

    A: “LIA (270 ppm) and the MWP (280 ppm) was separated by about 10 ppm, and we are currently about 100 ppm higher than during the MWP”

    B: “LIA (wasnt that caused more by a reduction in solar ouput?).”

    re A: this is like having your cake and eating it. It is hard to blame MWP (and the millions of other warmings through geological time - say one every 1000 years) on CO2, but you do blame the current warming solely (or mainly) on that, because they are “not alike”.

    Re B: solar output whether in terms of TSI, magnetic field, and EUV does not seem to have changed significantly in the last 400 years, so we should not attribute the LIA to the sun (however convenient it might be).

    “figure out what might actually happen”
    This is good advice, but if we are in panic mode we won’t accomplish much.

  • ks // October 29, 2007 at 2:16 pm

    Dr. S

    the words were not my own, hence the ” “. I fail to see how it was not a civil comment. You are trying to treat a problem as a single variable when it has been predicted to be multi-variable.

    For example, http://www.usaid.gov/our_work/environment/water/climate_change.html

    and no, I don’t think the author of the quote meant “weather variability.” Last I checked, drought was not considered weather.

  • EliRabett // October 29, 2007 at 2:46 pm

    Just to be clear Svalgaard is convinced that there has been no significant change in solar insolation in the past 400 years. There are not many in his field or who study climate who agree and there are multiple lines of evidence against it.

    However, that being the case you have the problem of what did cause the variations in climate that were observed. You could chalk it up to natural variability, but that stretches the envelope quite far.

  • cce // October 29, 2007 at 3:16 pm

    1) There is no way that the CO2 concentration is going to fall 100 ppm anytime soon.
    2) If it did it wouldn’t mean LIA conditions any more than it would mean MWP conditions
    3) The concentrations of many GHGs, among them CO2, N2O and Methane have been significantly thrown out of whack by human activities. Current conditions and the recent past are not “alike” because they are not “alike.” They are not alike in their causes, and they are not alike in the amount and speed of the temperature change.
    4) No one is advocating another LIA.
    5) You, however, are advocating increasingly warmer conditions, arrived at with unusual speed, on top of already warm conditions.

  • Leif Svalgaard // October 29, 2007 at 4:59 pm

    Eli: “just to be clear Svalgaard is convinced that there has been no significant change in solar insolation in the past 400 years. There are not many in his field or who study climate who agree and there are multiple lines of evidence against it.”

    There very careful phrase “solar insolation” calls for a clarification: as we don’t know what variation there has been in the Earth’s albedo over the last 385 years, I’ll discuss the solar output:

    There are two issues:
    1: does the solar output vary [other than by a trivial amount]?
    2: could and do these variations cause climatic changes?

    If the answer to 1 is “no”, then we don’t need to consider 2.

    A very authoritative review was published a few years ago:

    Solar radiative output and its variability: evidence and mechanisms, by
    Fröhlich, Claus; Lean, Judith,
    The Astronomy and Astrophysics Review, Volume 12, Issue 4, pp.273-320, 2004. DOI:10.1007/s00159-004-0024-1

    They summarize thus:
    “The historical irradiance reconstructions shown in Fig 30 b) all assume the existence of a longer term source of irradiance variability, in addition to the 11-year cycle. [...] Which of the time series in Figure 30 [can be found on my website http://www.leif.org/research click on CAWSES - IMF, EUV, TSI.pdf ( CAWSES Newsletter: vol 4, issue 2, new2007)] better represents actual irradiance variability is unknown. The primary uncertainty is whether the secular changes that the models assume actually occur (Willson and Mordvinov, 2003), or not (Foukal and Milano, 2001; Lean et al., 2002). Nor is the extant contemporary database of sufficient duration to adequately judge the various approaches. The comparisons in Figure 31 show that the historical reconstructions deviate from each other prior to 1980, which is when actual observations were just commencing. Lack of a clear physical relationship between the 14C and 10Be cosmogenic isotopes and irradiance variability is a critical impediment to improved understanding of long-term irradiance variability. Whereas the sources of irradiance variability are magnetic active regions near the surface of the sun, cosmogenic isotopes variations occur because the extended solar atmosphere in interplanetary space modulates the flux of galactic cosmic rays that reaches the Earth’s atmosphere (Bard et al., 2000; Webber and Higbie, 2003). The recent simulations of magnetic flux transport on the sun, suggesting the lack of a linear relationship between total and open flux (and hence irradiance and the interplanetary magnetic field) are preliminary, and raise additional questions about the role or meridional transport and the extrapolation of surface magnetic fields to the corona and heliosphere that require further study.”

    Such further studies are now becoming available. And they seem to indicate that the variation of both TSI and solar magnetic output are much smaller that thought in 2004. I can mention two:

    Shortwave forcing of the Earth’s climate: Modern and historical variations in the Sun’s irradiance and the Earth’s reflectance, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 69, Issue 13, September 2007, Pages 1556-1568, by P.R. Goode and E. Pallé.

    They conclude:
    “From the helioseismic data, we now have an internally consistent picture of the origin of frequency changes that implies a Sun that is coolest at activity maximum when it is most irradiant. [...] We conclude that the Sun cannot have been any dimmer, on the time steps of solar evolution, than it is now at activity minimum.”

    A Floor in the Solar Wind Magnetic Field, by Svalgaard, L.; Cliver, E. W., The Astrophysical Journal, Volume 661, Issue 2, pp. L203-L206., 2007, DOI:10.1086/518786.

    They conclude:
    Various lines of evidence indicate that the solar wind magnetic field has a “floor” or baseline state to which it falls when the sunspot number goes to zero for extended intervals (several rotations). During such periods, the IMF in the ecliptic plane at 1 AU is ~4.6 nT, and the radial component of the polar IMF at 1 AU is ~3 nT, independent of the solar polar field strength. The floor appears to have been stable since ~1500. We identify the floor with a constant solar open magnetic flux of ~4×1014 Wb and a constant corresponding strength (~1011 A) of the current in the HCS. Solar cycle variations of the IMF ride atop the floor. The existence of a floor in the solar wind has a bearing on
    such topics as the solar dynamo, space weather, and cosmic ray modulation. Specific implications of the floor for solar grand minima, solar wind models, [...] were discussed in § 3. The basic question of how the Sun maintains a constant baseline open flux in the face of variable polar field strength remains unanswered. The strength of the solar polar fields does not determine the IMF strength.”

    The evidence is pointing to a lack of a secular variation of any “background” solar irradiance [possibly caused by solar magnetic fields], and that leaves the variation [as Goode and Palle delicately note] “climatologically small”.

  • Leif Svalgaard // October 29, 2007 at 5:20 pm

    In case my long post didn’t hit home, it can be summarized thus:
    ‘The solar output during the Maunder Minimum was what it is right now, today.’ Both for TSI and for the magnetic field.

    If there was no lower output to explain the LIA, there must be other natural causes, that are not considered by deniers.

  • CraigM // October 29, 2007 at 11:26 pm

    dr. leif

    “… if we are in panic mode we won’t accomplish much.”

    well, we cant turn everything off. I cant image walking into a hospital and turning every heart monitor off, sheesh. It would be utter disaster. We have to encourage new technology and become more efficient with our energy usage. We have to do that but at the same time not damage our economy so much thats things go pear shaped there.

    The thing is, we havent been in panic mode for 15 years. In fact we have done very little. Panic mode is more likely to come about if we sit on our hands and wait. I mean, if we wait and wait and things dont turn out the way we like in terms of climate then you are likely to see panic on a scale you aint seen before. So we dont want panic, no doubt.

    Right now is a good time to start implemeting a few simple strategies to encourge new technology: carbon taxes, cap and trades, targets for emission reduction….whatever. The sooner we do that the less damage we will do to our economy because things can be spread out over numerous years. Do that now and we can slow this climate change thing down a bit. We are locked in to some warming now it seems. And there we will have to work on our adaptive strategies too. But im all for slowing things down and acting early, yknow, with a bit of fore-thought and not leaving everything to the last minute.

    So i guess, in summary:

    Im all for slowing down climate change. So we have plenty of time to adapt and figure out whats going on…

    To do the above means acting early in terms of adjusting our economy, so we dont suffer too much of an economic shock.

    thats my 2c

  • Leif Svalgaard // October 30, 2007 at 1:47 am

    Craig,
    Reducing emissions is good in itself as it leads to a cleaner air. When I worked in L.A. in the early seventies, you couldn’t see across the street on most days, that is much better today. In China they have severe problems with foul air and they need to do something about that. London’s smog is mostly gone now because of not burning sulphuric coal . A cleaner environment is something to desire in itself.
    I don’t think we disagree there.

    About ‘panic’. The ‘planet in peril’ and ’save the planet’ things look like panic to me, or at least an attempt to create panic. In a panic some people are always been taken advantage of and swindled. This we don’t need. A measured approach as you (and I, actually) advocate is very hard to emerge from the vitriolic ‘debate’ that is taking place. The improvement in climate that may have resulted from burning fossil fuels
    may come to an unfortunate end as oil climbs above $100 a barrel (it was near $94 today), as conservation may come simply because it is becoming too expensive to burn the stuff.

    In my previous post and in others I have tried [albeit with little success] to point out that all the previous millions of warming [assuming that the last 3000 years are typical - I even take away from that number the last two decades] were not caused by humans injecting 14C from burning fossil fuels. There are indications that variations in solar output are “climatologically small”, so I think we are neglecting or not understanding some other natural fluctuations.

  • Dano // October 30, 2007 at 2:26 am

    I can actually find a point of agreement with Leif - I don’t like the ’save the planet’ stuff either. The planet will carry on long after we destroy ourselves. It’s arrogant to think otherwise.

    Nonetheless, Leif, the last 650k years are the key record length, as this recent time period covers most of the adaptations made by plants (albeit not the grasses, the most-advanced of the plants) and most of the adaptations by animals to recent planet-wide ecosystem swings (and CO2 ppmv has never been higher in this time period than now.

    We learn little about earth systems wrt adaptation by looking 55MYA.

    Best,

    D

  • dhogaza // October 30, 2007 at 3:20 am

    In my previous post and in others I have tried [albeit with little success] to point out that all the previous millions of warming [assuming that the last 3000 years are typical - I even take away from that number the last two decades] were not caused by humans injecting 14C from burning fossil fuels.

    Sure, but humans weren’t around to be driven to extinction by such events millions of years ago (if I interpret “millions of warming” correctly).

    You do understand the basic selfishness of our concern, right? As Dano points out, we’re not really talking about “saving the planet”, we’re about saving OUR SPECIES.

    OK, even that’s perhaps more extreme than necessary. We’re talking about “minimizing the number of humans killed”.

  • Leif Svalgaard // October 30, 2007 at 3:50 am

    re number of warmings: there seems to be warming about every 1000 years; none of these except perhaps the last can be attributed to humans ‘tampering’ with the climate by releasing CO2. For the sun to be the culprit, the climate sensitivity to the minuscule solar variations must be much, much higher than we thought it was [cf. Goode and Palle] and if so, maybe the current warming is mainly due to the sun. There are [respected] solar physicists that argue that the sun now is more active that in the last 11,000 years. [Unusual activity of the Sun during recent decades compared to the previous 11,000 years, S. K. Solanki, I. G. Usoskin, B. Kromer, M. Schuessler, J. Beer,
    Nature 431, 1084 - 1087 (28 Oct 2004) Letter]. That combined with the Goode&Palle hypersensitivity might mean that most of the current warming is due to the sun. I mention this as a possibility, although I personally do not believe so [that the sun is so unusual now].
    Whether or not we consider the last 650,000 years or billions of years does not alter the arguments that has been MANY warmings even under close to current conditions.

    “saving our species”: there seems to me to be a much larger chance that we do ourselves in by warfare than by climate change. And talking about ’saving our species’ is the kind of alarmist cry that leads into panic if enough people go for it. I can just see the headlines: “Maybe we need to bomb them chinks into reducing their carbon footprint”.

  • Hank Roberts // October 30, 2007 at 4:03 am

    Bribes, not bombs.

    The smart move would have been to develop the “no regrets” technology over the past 20 years and had it ready to sell as the Chinese reach the point of really nasty air pollution and developing environmental activism.

    Instead — if we’re lucky — they shut down enough vehicles and factories to have a breathable Olympic Games, doing the great experiment no other country has done (with the exception of the USA shutdown of aircraft operations for 3 days after 9-11).

    Those experiments are the ones that are convincing, they make very clear what the effects of human activity are.

    China really wants an Olympic Games where the athletes don’t have breathing problems.

    So they’re going to do the experiment there with cars and factories.

    Let’s hope they also instrument the heck out of the area and get good science out of it, convincing science, knowing that they are positioned to profit from doing so.

    With luck, they do that, and we get the chance at best to design along with them and see them manufacture the next generation technology that allows controlling the pollutants better than our 1960s-1970s technology.

    They leapfrog us. So it goes. Maybe.

  • nanny_govt_sucks // October 30, 2007 at 6:23 am

    … this recent time period covers most of the adaptations made by plants

    Dano, can you explain why most plants thrive best at around 1000-1200ppm CO2?

  • Dano // October 30, 2007 at 1:43 pm

    Define ‘thrive’ and where this ‘thrive’ occurs, plz.

    Best,

    D

  • Dano // October 30, 2007 at 1:48 pm

    And talking about ’saving our species’ is the kind of alarmist cry that leads into panic if enough people go for it. I can just see the headlines: “Maybe we need to bomb them chinks into reducing their carbon footprint”.

    Fellow Pompeiians! Fear not the rumblings beneath your feet!

    Anyway,

    If I may, Leif, you either know nothing about terrestrial ecosystems and their responses, or you know something but don’t share it with others. Our Western societies are entirely dependent upon ecosystems. Perturb them beyond their tipping points and we’re living in systems for which we have no precedent for living, for economy, for growing crops.

    You may want a hard landing for societies, but I don’t. Hard landings are, well, hard. Sounds cruel to me.

    Best,

    D

  • John Cross // October 30, 2007 at 3:30 pm

    Nanny: I think you took your argument from the first paragraph without reading the rest.

    So please back up your assertion.

    Regards,
    John

  • Hank Roberts // October 30, 2007 at 3:35 pm

    http://pediatrics.aappublications.org/cgi/content/abstract/peds.2007-2645v1?ct

  • luminous beauty // October 30, 2007 at 4:00 pm

    Leif,

    I would say we have a pretty good theoretical understanding of natural climate variation, i.e. GCMs. How well they correlate to what real-world mapping we have, low resolution as it may be, is compelling if not absolutely probative.

    You are absolutely right on that solar variability does not appear to be much of a factor. What is telling to me is that until we began observing the sun from space, for all we knew, TSI was a constant. I also suspect that hyper-climate sensitivity would hold for the IR rebound of greenhouse gasses as well. Even more so, as the sun only shines on half the planet at any given moment.

    I do appreciate your big picture deep time astronomical perspective, but we do have to live on this planet.

  • Leif Svalgaard // October 30, 2007 at 4:29 pm

    luminous beauty:

    to quote myself: “TSI during the Maunder Minimum [and other Grand Minima] was not any lower than what it is today, right now, this minute”.

    This means that *unless* climate sensitivity to solar forcing is an order of magnitude higher than commonly thought [and 'understood'], the LIA was not caused by the sun, the MWP, the ‘Roman’ warming [e.g. grapes grown in England during Roman times] was not caused by the sun, and all the other warmings and coolings were not caused by the sun either. And they were not caused by man-released CO2 either, so there is enough natural terrestrial variability present to account for those, leading to the question how much of the present warming is due to those natural causes and how much is due to human activity. Simply to say that the current warming is mainly man-made, is akin to the argument for why Uri Geller’s current spoon-pending trick is genuine given that in the past he was shown to be a fraud.

    [Response: As an aside, there is at least one researcher (William Ruddiman) who argues that anthropogenic CO2 has been an important climate forcing for a very long time (6000 years or more), not due to fossil-fuel burning but because of land-use changes associated with agriculture. He argues that if not for human activity, we'd be well into the next ice age. I think most in the climate science community would reserve judgement, neither affirming nor denying its correctness.]

  • Leif Svalgaard // October 30, 2007 at 5:45 pm

    Yes, I’m aware of Ruddiman and there might be something to it. My point is that both his mechanism and the current CO2 injection probably have some effect, but those are on top of the natural causes and we don’t know how much is really due to either. But he and I apparently agree that human activity has been for the better. When fossil CO2 runs out [don't know when], the CO2 that we put into the atmosphere begins slowly to settle out and after some time [centuries?] will be back to the pre-industrial value, and maybe we cannot stave the ice age off anymore.

    on a different note: the current hurricane season has turned out to be flop (like the last one). This is, of course, a disappointment to the alarmists, but there is always NEXT year…

    [Response: It's my opinion that computer model simulations of the 20th century (see the IPCC report for more details) argue strongly that we *do* have a pretty good idea "how much is really due to either." If you want an opinion from leading researchers, you could inquire at RealClimate.

    I was under the impression that the 2006 hurricane season in the Atlantic was average, not a "flop," and that the season in the Pacific was quite active. In any case, the lack of destructive storms striking the U.S. over the past two years is not a disappointment to me, it's a relief. But I don't consider myself an "alarmist"; I'm hoping to avert disaster rather than celebrate it. Perhaps that's a line of demarkation between the concerned and the genuinely alarmist.]

  • Dano // October 30, 2007 at 6:17 pm

    This is, of course, a disappointment to the alarmists, but there is always NEXT year…

    I’d like to know who these straw-people are. Can anyone name these mythical hair-shirt wearers who profess (loudly, surely for Leif to know what they want) their disappointment over a lack of destruction (presumably so we can go back to feudal times)?

    Best,

    D

  • tamino // October 30, 2007 at 6:33 pm

    I reiterate: if something is said which angers you, please exercise exceptional restraint in responding.

    At the same time, I’ll agree with Dano that the comment “This is, of course, a disappointment to the alarmists” strikes me as an unnecessary straw-man.

  • Leif Svalgaard // October 30, 2007 at 6:53 pm

    tamino: It’s my opinion that computer model simulations of the 20th century (see the IPCC report for more details) argue strongly that we *do* have a pretty good idea “how much is really due to either.”

    In that case one should be able to quantify that, so, let’s try. Consider the sequence of events:
    RW (Roman warming)
    MC (Early medieval cooling)
    MW (medieval warming)
    LIA (little ice age)
    CW (current warming)

    put three numbers (e.g. degrees change) on each event. The first number is solar forcing, the second one is “natural variability” and the last one is that due to human influence [I'm not including Ruddiman here]. If you can do that and show why EACH of the numbers is as you put them, I’ll agree that we have a ‘pretty good idea “how much is really due to either”‘. If not, I’ll say that we do not have such a good understanding of these things.

    hurricanes 2007: I live in Houston, so I follow the tropical activity closely. Evacuated during Rita. It is almost impossible to get real information nowadays, but if what I see matches my own experience, it registers positively with me. Here is my source:
    http://www.coaps.fsu.edu/~maue/tropical/
    By: Ryan N. Maue, Florida State University
    Cross Post at Climate Audit (h/t) Steve McIntyre
    “Unless a dramatic and historical flurry of activity occurs in the next 9 weeks, 2007 will rank as a historically inactive TC year for the Northern Hemisphere as a whole. During the past 30 years, only 1977, 1981, and 1983 have had less activity to date (IMAGE: January-TODAY, Accumulated Cyclone Energy ). For the period of June 1 - TODAY, only 1977 has experienced LESS tropical cyclone activity than 2007. For the North Atlantic basin, Tropical Storm Noel is currently too weak to impact any of these results. However, one should always be prepared for late-season developments since hurricane season ends on November 30.”

    2007 lowest September activity on record since 1977
    2006 and 2007 lowest October activity on record since 1976 and 1977

    You are clearly not one those you want to exclude from posting because of foul language etc [kind of the opposite of G. Marx: I don't want to belong to a club that would accept me as a member :-)] so perhaps one mark of a concerned person is civility. If so, one has a handy way of determining on which side of the line of demarcation someone is.

  • Leif Svalgaard // October 30, 2007 at 7:18 pm

    “disappointment to the alarmists”

    how can there be ANY doubt that I did not mean that some people want destruction? What do you take me for? What I clearly meant was if 2006 and 2007 HAD have many severe and destructive hurricanes, that some people would have said: “see, do you now understand how important it is that we stop tampering with the climate” using the many hurricanes as support for their viewpoints without taking the few hurricanes as weakening their argument.

    [Response: I have no doubt that you did NOT really mean that some people would delight in destruction. But can you see how it might be misinterpreted that way? Certainly Dano thought so. And we have actually heard pretty much exactly the same words before, from people who *did* intend that reprehensible meaning.]

  • Dano // October 30, 2007 at 8:19 pm

    Hmmm…mild sarcasm discouraged. Understood.

    (you can delete if you wish, sir).

    Best,

    D

    [Response: I actually enjoy mild sarcasm. My comment was more a warning than a criticism. And please bear in mind I'm being extra cautious, in order to establish a new order of things. Generally, it's going pretty well, people seem to be doing a fine job abiding by the new practice, the tone of commentary is *much* better, and the commentary itself seems much more to the point and productive.

    I really do hope to loosen up soon. One difficulty is that traffic -- both hits and comments -- have actually increased since the new policy, contrary to my expectation.]

  • JesusChristHimself // October 30, 2007 at 8:48 pm

    On named hurricanes, Houston recently had 5 billion in property damages and lost 22 human beings. The storm had a name, but it wasn’t Rita.

    Several years ago hurricane experts recommended Galveston build a seawall. The good folks decided they had better things on which to spend their money. They revisited the arguments, and built an especially expensive seawall.

  • nanny_govt_sucks // October 30, 2007 at 9:04 pm

    Define ‘thrive’ and where this ‘thrive’ occurs, plz.

    For more info:

    Please see the first full paragraph on the page here:
    http://tinyurl.com/32jfek

    Also, there’s http://ars.usda.gov/is/AR/archive/jul97/gcc0797.htm which experimented with a doubling of CO2 concentrations (still far above what we see in the ice cores record).

    It would seem that plants “remember” a time when CO2 concentrations were much higher, does it not? Or is there some other interpretation?

  • Heretic // October 30, 2007 at 9:08 pm

    “One difficulty is that traffic — both hits and comments — have actually increased since the new policy, contrary to my expectation.”

    Bloggers are like children, they need boundaries…

  • tamino // October 30, 2007 at 9:27 pm

    Leif:

    one should be able to quantify that

    Others far more capable than I have already done so, although estimates of climate forcings generally don’t extend much beyond the last thousand years. Series of estimated forcings usually include solar, volcanic aerosols, and greenhouse gases. Examples are Bard et al. 2000 (Tellus B, 52, 985-992); Mann et al. 2005 (Journal of Climate, 18, 417-456); Crowley 2000 (Science, 289, 270-277). Quite a few forcings are estimated for the last 400 years in Robertson et al. 2001 (J. Geophys. Res., 106, 14783-14803). NASA GISS has forcing estimates since 1880 for well-mixed greenhouse gases, ozone, stratospheric water vapor, land use, snow albedo, stratospheric aerosols, black carbon, and the aerosol indirect effect.

    There’s a great deal that isn’t known about climate forcings and climate dynamics. But we’re not just taking potshots in the dark; an immense amount of work has gone into understanding, and quantifying, these things.

  • Dano // October 30, 2007 at 9:50 pm

    I appreciate the fact that, na_gs, you can’t find anything older than 1997, despite the plethora of research since then, including the research I included in the 44 other times I’ve responded to your assertions.

    Likely this time issue is because many of the actual FACE results disagree with your assertion, but as to your impaired memory restricting your assimilation of the provided material…what could the reason be?

    Best,

    D

  • Leif Svalgaard // October 30, 2007 at 10:00 pm

    “one should be able to quantify that …
    Others far more capable than I have already done so”.

    I do understand that an immense amount of work has been done. In my own field, if people asked me a similar kind of question I would be able off the top of my head to quote at least orders of magnitude for the contents of my little table. F.ex.: in degrees C [solar, natural, human]
    RW [0, 3, 0]
    MC [0, -2, 0]
    MW [0, 3, 0]
    LIA [0, -2, 0]
    CW [0, 2, 1]

    or some such numbers. I would take a certain pride in being able to do that without having to ask the questioner to go look it up among that “immense amount of work”.

    Other people here who KNOW at lot more than I might prefer a different table, e.g.:
    RW [0, 0, 0] denying that it was there
    MC [0, 0, 0] denying that it was there
    MW [0, 0, 0] denying that it was there
    LIA [-2, 0, 0] the sun did it
    CW [0, 0, 3] we did all of it
    With such a table, the discussion gets onto a firm foundation, because each particular number can now be referred back to the precise papers that deal with that particular time or the precise formula or model that allows that particular number to be derived.

    Without such SPECIFIC numbers, I’ll maintain [at least to my satisfaction] that we do not have a “pretty good understanding”. Now, it’s perfectly OK that different people have vastly different tables in mind. That is regular science: we have SPECIFIC disagreements and they can be resolved by further research [and might even show what need to be looked at]. So, I would issue a challenge: let every participant here state what his/hers table looks like. It is OK to use question marks, e.g. the table
    RW [?, ?, ?]
    MC [?, ?, ?]
    MW [?, ?, ?]
    LIA [?, ?, ?]
    CW [?, ?, ?]
    is perfectly valid [albeit a bit uninformative].

  • jonathan // October 30, 2007 at 10:25 pm

    Somehow nature is absorbing 55% of our CO2 emissions. So cutting CO2 emissions by 45% will stop the rise of CO2 in the atmosphere. Thats about what burning coal contributes. So lets replace every coal power plant by a nuclear one and put out those HUGE coal seam fires in China!

  • tamino // October 30, 2007 at 11:13 pm

    I’ve never claimed that climate science is my field, let alone paleoclimate, and I don’t have estimates off the top of my head. But I do have enough data on my computer to make very rough guesstimates:

    RW [?, ?, ?]
    MC [?, ?, ?]
    MW [+0.2, 0, 0]
    LIA [-0.2, -0.2, 0]
    CW [+0.1, -0.1, +0.8]

    These are not pronouncements, I’m just “taking a stab” at it. If you want real expert opinion, look in the literature.

    As for this:

    I would take a certain pride in being able to do that without having to ask the questioner to go look it up among that “immense amount of work”.

    I tried to point you to far better estimates of paleoclimate influences than I’m able to supply. To be perfectly candid, I think you would greatly benefit from looking up some of that immense amount of work.

  • Leif Svalgaard // October 30, 2007 at 11:47 pm

    tamino
    in your your table, what are the numbers? degrees C? I see numbers like several degrees floating around.
    does it mean that you think there was no MW except the measly +0.2 due to solar forcing?
    And RW and MC are hardly paleoclimate. These events are recent enough to be within the range of conditions similar to now and their causes are of immediate interest. Since you discount MW maybe you also discount RW ad MC? in which case, of course, it is moot what their causes were. I’ll maintain that without firm numbers (rather than “stabs”) there can be no serious discussion. Suppose I in a week came back to say that I’ve scoured the literature and that I found CW [+0.1, +2.1, +0.8], would you accept that? I don’t think so. You must [should] have a specific reason for CW [+0.1, -0.1, +0.8] rather than CW [+0.1, +2.1, +0.8]. As I said, EACH number can be and should be accounted for. Just telling to RTFM is not enough.

  • nanny_govt_sucks // October 30, 2007 at 11:49 pm

    I’m not referring to soil fertility, Dano. That’s 2 evasions. Is this a difficult question?

  • Hank Roberts // October 31, 2007 at 12:29 am

    A happens.
    Yes, if you also have B.

  • EliRabett // October 31, 2007 at 1:20 am

    Of course the possibility that shall not be named is simply that Svalgaard is wrong. Which seems a reasonable POV. I would also not get sucked into the Rome warming bit, because frankly no one has more than a guess what the Italian temperatures were, let alone the global temperatures\let alone the forcings. That little side track seems to be a red herring in a red herring barrel.

  • tamino // October 31, 2007 at 1:34 am

    in your your table, what are the numbers? degrees C?

    Yes. That’s what you asked for.

    I see numbers like several degrees floating around.

    Where? From what I’ve seen, several degrees is absolutely not credible.

    does it mean that you think there was no MW except the measly +0.2 due to solar forcing?

    Why do you call it “measly”? Do you have solid evidence that it is otherwise, or are you basing this on numbers “floating around”?

    I based my estimate of the size of the MWP and LIA on the Moberg reconstruction (smoothed with a low-pass filter), adjusting for the fact that it’s only hemispheric, not global. I based the fraction attributable to different causes on the forcing estimates of Crowley, except for the modern era which is based on forcing estimates from NASA GISS.

    And RW and MC are hardly paleoclimate.

    The National Academy of Sciences report on the reliability of climate reconstructions for the last 2,000 years refers to it as paleoclimate.

    The NAS report expresses high confidence in paleoclimate reconstructions for the last 400 years, less confidence in reconstructions back to the year 900, and low confidence in reconstructions before that. I have yet to see a reconstruction of sufficient precision to address the question, which extends before the year 0, and those I’ve seen which go back that far are only hemispheric. So to posit RW and MC as though they were established facts seems not credible.

    Statements like this one of yours, your earlier questioning whether CO2 increase is primarily anthropogenic, and some of your comments on the IPCC report, are why I suggest that you would greatly benefit from a lot more study of the literature.

    I’ll maintain that without firm numbers (rather than “stabs”) there can be no serious discussion… Just telling to RTFM is not enough.

    I’ll maintain that if you want a serious discussion, RTFM is what you most need to do.

  • Dano // October 31, 2007 at 1:55 am

    I’m not referring to soil fertility, Dano. That’s 2 evasions. Is this a difficult question? /i>

    na_gs, if you can’t understand that there are conditional propositions for ‘thrive’, then you are being used.

    And you may want to mouseover more than one link before you choose a rhetorical tactic with me.

    Conditionality and multiple factors are why I asked for the definition of ‘thrive’ and where this ‘thrive’ occurs, as it doesn’t occur in ag because of what I alluded to earlier, and it doesn’t occur in forests due to N and HOH limitations (and some O3). So that eliminates ‘most plants’.

    So, I give you another opportunity to, instead of old news, you should answer in your own words if you wish to eliminate past precedent and appear credible, rather than appearing to cut-paste sans comprehension.

    Second, rhetorically, if you also must hand-wave and can’t address the fact that I gave more recent research that sheds new, bright light on your old news, then you aren’t playing in a very fun way at all.

    You’ll want to address why your 1000-1200ppm CO2? statement isn’t true, not distract away from the fact that you wrote something that isn’t true.

    Please explain why 1000-1200ppm CO2 ‘thriving’ isn’t ‘thriving’ at all.

    Thank you in advance for not straying off topic.

    Best,

    D

  • luminous beauty // October 31, 2007 at 1:59 am

    Leif,

    Paleoclimate is roughly definable as that which precedes the instrumental record. That would include RW and MC.

    Just about everything before the 20th century that can be resolved on a global scale.

  • Dano // October 31, 2007 at 2:33 am

    Preview good.

    I can’t always see when I haven’t closed a tag, esp. after a Bushmill’s after a loooong day.

    Best,

    D

  • Leif Svalgaard // October 31, 2007 at 2:48 am

    “I’ll maintain that if you want a serious discussion, RTFM is what you most need to do.”

    When I do, I see things like this:

    Science 29 November 1996:
    Vol. 274. no. 5292, pp. 1503 - 1508
    DOI: 10.1126/science.274.5292.1503

    The Little Ice Age and Medieval Warm Period in the Sargasso Sea

    Lloyd D. Keigwin

    Sea surface temperature (SST), salinity, and flux of terrigenous material oscillated on millennial time scales in the Pleistocene North Atlantic, but there are few records of Holocene variability. Because of high rates of sediment accumulation, Holocene oscillations are well documented in the northern Sargasso Sea. Results from a radiocarbon-dated box core show that SST was ~1°C cooler than today, 400 years ago (the Little Ice Age) and 1700 years ago, and ~1°C warmer than today 1000 years ago (the Medieval Warm Period). Thus, at least some of the warming since the Little Ice Age appears to be part of a natural oscillation.

    The range here is 2 degrees. It seems that one can cherry pick one’s numbers from the immense amount of work out there. You see, I’m here to learn, but the signals I get don’t match.

    My good friend [the late] Gerard Bond [http://lasp.colorado.edu/sorce/news/sns/2003/sns_dec_2003.pdf] looked at sediments deposited on the ocean floor by the melting of icebergs from eastern Canada. He found that a cycle of warming climates released the icebergs every 1000-1500 years or so, leading to a periodic cooling of the ocean by several degrees. He could follow these events 100,000 years back [published in Nature, 1993].

    Now, the standard argument against stuff like this is that the cycles were just regional, etc., and I don’t know how valid that is. It may be that climate changes e.g. in the polar regions are large, but when averaged over the whole globe they diminish by an order of magnitude. So maybe what is important is just the relative size of the numbers.

    Your numbers:
    MW [+0.2, 0, 0]
    LIA [-0.2, -0.2, 0]
    CW [+0.1, -0.1, +0.8]
    ascribe significant effect to solar forcing and that is something I do not think is justified. You can, however, find many papers in the literature that claim a significantly large solar effect, but just toting up papers on both sides of the argument and comparing the number of papers found is not fruitful.

    If you move the solar part for the LIA over in the “natural causes” column you are getting close to my view that there are significant natural variation.

  • Leif Svalgaard // October 31, 2007 at 3:35 am

    with the solar forcing = 0, your table looks like this:
    MW [0, +0.2, 0]
    LIA [0, -0.4, 0]
    CW [0, 0, +0.8]

    so the natural causes [NC] for LIA seem to be half of human causes [HC] for CW, What is the basis for saying that NC for CW is zero? since we don’t know what NC are nor model NC, how can we say that there are no NC for CW?

  • Leif Svalgaard // October 31, 2007 at 3:48 am

    I have a small confession to make. I have an ulterior motive for beating this dead horse, namely that I’m giving a paper in the ‘Global Climate Change’ session at the Fall meeting in December of the American Geophysical Union:

    GC31B-0351: (No?) Century-scale Secular Variation in HMF, EUV, or TSI, Leif Svalgaard.

    Since it is almost dogma that (”of course”) the sun influences the climate, it is hard to get people to listen when you say that the sun does not vary on longer timescales so this blog here is a good training exercise for me on how to deal with a hostile crowd :-)

  • ks // October 31, 2007 at 4:29 am

    “since we don’t know what NC are nor model NC, how can we say that there are no NC for CW?”

    you should probably read the IPCC AR4 before prematurerly jumping to this conclusion. figure 22 of the Technical Summary (page 61 of the report) consists of a comparison of observed changes to modeled anthropogenic and natural forcings. You should probably also look at FAQ 9.2 (page 702) “Can the warming of the 20th century be explained by natural variability?” I’ll go one step further and recommend the full chapter 9, “Understanding and Attributing Climate Change” with the relevant section “Understanding Pre-Industrial Climate Change”

    My own advice would be to not claim something has not been done in another field without first looking to see if that is indeed true.

  • nanny_govt_sucks // October 31, 2007 at 4:38 am

    na_gs, if you can’t understand that there are conditional propositions for ‘thrive’, then you are being used.

    Is this something about the definition of “is”?

    It’s not a complicated question, Dano. It seems that optimal CO2 concentrations for plants are somehwere above 1000ppm, yet we don’t see concentrations that high in the ice cores record. Why do you think that is?

  • Hank Roberts // October 31, 2007 at 7:16 am

    Because it requires excesses of nitrogen and minerals, beyond what’s available in natural environments. Because nature doesn’t do ‘optimal’ —

    “optimization requires processes that are more complex than those needed to merely satisfice” [satisfying the minimum requirements]
    wordnet.princeton.edu/perl/webwn

    Success in nature is measured by fitness, loosely defined as number of grandchildren. Success in gardening is defined as maximum yield with all necessary effort to supplement everything to achieve that, far beyond what a plant’s got to do to get viable seed into the next generation.

  • Dano // October 31, 2007 at 12:02 pm

    It seems that optimal CO2 concentrations for plants are somehwere above 1000ppm,

    na_gs, recent findings dispute this statement, despite your concerted attempts to ignore this fact. You can’t hand-wave away from this.

    Thank you for playing, but I’m bored with the level of argumentation presented.

    Best,

    D

  • nanny_govt_sucks // October 31, 2007 at 4:45 pm

    Dano, the recent findings you pointed to included study of soil fertility limitations to growth, and the introduction of ozone which is “toxic to plants”. I’m sorry, but this is not what I am referring to. I am specifically talking about optimal CO2 concentrations for plants. But I’m sure you know that.

  • tamino // October 31, 2007 at 5:15 pm

    Leif:

    It looks like you’re going to try to sell no-solar-variation to the AGU climate science community. It won’t be easy, but it may not be as hard as you expect. Here’s my advice, for what it’s worth, take it with a grain of salt.

    Be cautious making statements outside your field. Frankly, you have made some statements here that would be very embarrassing.

    It helps to be familiar with the IPCC AR4. For an audience of climate scientists, this is the conservative concensus. And don’t be too critical of it; a lot of your audience will be the people who wrote it. But don’t worry too much about learning the whole field of climate change; you’re there to talk about the sun.

    Regarding climate of the last two thousand years, it may be to your advantage that the estimated global temperature changes are actually quite small by comparison to modern temperature change. Yes, there are lots of studies showing things like swings of several degrees in SST in the Sargasso Sea, but SST isn’t global surface temperature and the Sargasso Sea isn’t the globe. When it comes to explaining global temperature variations over the last few millenia, the concensus view is there really isn’t much to explain.

    But what little does exist, seems to need some explanation. I think simply calling it natural variation will be a hard sell. Pure internal variability looks like a stationary process, small at that, and seems to be able to bring about significant local variations with little affect on global temperature. The audience will want to understand things like MWP and LIA, however small they may be thought to be, in terms of physically explicable changes to the planetary energy balance (solar, volcanic activity, albedo changes, land use, greenhouse gases, etc.). Solar is an appealing hypothesis because it obviously impacts energy balance, and its effect is global.

    You may well be asked why, if the sun isn’t a factor, do solar reconstructions correlate reasonably with estimated climate changes. Lots of people think the LIA is at least partly due to reduced solar activity, and the coincidence with the Maunder minimum may be brought up. But the LIA appears to start before the sunspot record begins, and I have the impression that solar reconstructions before the telescope era are mainly based on abundances of cosmogenic isotopes (I’ll bet you know a lot more about it than I do). That has always struck me as sketchy evidence. As I understand it, cosmogenesis is a proxy for the interplanetary magnetic field, which itself is a proxy for solar output, so we’re dealing with a “proxy of a proxy” and you could emphasize its uncertainties. For estimates from the telescopic era, the Lean reconstruction is very popular, be prepared to address the question why it should not be relied upon.

    A very big source of skepticism in your audience will be the 20th century. Computer models do an excellent job reproducing 20th-century temperature change, and they include solar variations to do so. Again, you could emphasize uncertainties in some of the other factors (without disparaging them). And don’t forget that you don’t have to explain any discrepancies; give them good cause to doubt solar variations, they’ll go looking for an explanation themselves.

    Play to your strength. You’re a solar physicist, they are not — this is AGU, not AAS. Focus on the sun and your evidence that its variability is negligible; don’t worry too much about explaining climate, that’s their job.

    Finally, don’t assume they’ll be hostile. They’re not solar physicists, and AGU is not the blogosphere. The solar advocates who arouse suspicion among climate scientists are trying to establish more solar influence on climate, and you seem to be moving in the other direction.

    For the love of God, don’t breathe a word about your belief that global warming will be good for us unless you want to ignite a firestorm.

  • Dennis Wingo // October 31, 2007 at 6:47 pm

    Tamino

    For CO2 these feedbacks are well quantified. They are identified in Loudon’s “The Quantum Theory of Light” page 83-104.

    Guess what, you need the QM equations to get the exact value of the CO2 feedback.

    [Response: I think you misunderstand completely. I also get the distinct impression you're trying to insist that quantum mechanics is essential to any quantitative treatment of its greenhouse-gas effect, and I disagree.

    CO2 feedback refers to the fact that temperature increase can trigger processes which release more CO2 into the atmosphere. This includes reduced solubility of CO2 in ocean water, melting of permafrost, and wasting of ice sheets. I seriously doubt these are identified in Loudon's "Quantum Theory of Light."]

  • Dano // October 31, 2007 at 6:57 pm

    I am specifically talking about optimal CO2 concentrations for plants.

    The references you provided to back your assertion were outdated, BTW. I provided updated findings which refuted your assertions, as I have the previous 47 times we’ve been thru this (albeit not at this site).

    Now I grow bored at the same tactics as the last 47 times, as I’ve corrected the incorrect assertion yet again & move on.

    Best,

    D

  • Eli Rabett // October 31, 2007 at 7:20 pm

    It’s not dogma that the sun varies on a centuries time scale, it’s what the solar physicists, et al. have been saying since the year dot. So if we are going to assign responsibility for this, it does not rest with the climate science community but with the guys and girls in the solar physics community (SPC). That being said, the most recent “dogma” pronouncements from the SPC decreases the amount of variation and this is reflected in the AR4. Still zero is the bottom of the range.

  • nanny_govt_sucks // October 31, 2007 at 8:18 pm

    Dano, as I pointed out in my previous post, your links were referring to different subjects.

  • Hank Roberts // October 31, 2007 at 10:25 pm

    Nan, you’re talking about gardening — optimization, by intelligently designing the conditions for maximum yield of just the one plant of interest. Right?

    If so, no argument, people can do that.

    Nature doesn’t. Any argument there?

  • Dennis Wingo // October 31, 2007 at 11:08 pm

    CO2 feedback refers to the fact that temperature increase can trigger processes which release more CO2 into the atmosphere. This includes reduced solubility of CO2 in ocean water, melting of permafrost, and wasting of ice sheets. I seriously doubt these are identified in Loudon’s “Quantum Theory of Light.”]

    I see. What is in Loudon is the qualitative effect on absorption and emission of infrared energy from increased CO2 concentrations. I would appreciate if you could point me toward any treatment of this subject that is better than what is at realclimate.

  • Hank Roberts // October 31, 2007 at 11:42 pm

    Dennis, feedback is going to change amounts of CO2, water vapor, and stratospheric chemistry.

    When you ask for an answer that’s “qualitative” you’re asking for the kind of information that is used to explain in simple terms, but that comes _after_ the math is done or else it’s just speculation.

  • George // November 1, 2007 at 5:47 pm

    Leif Svalgaard said:

    “solar output whether in terms of TSI, magnetic field, and EUV does not seem to have changed significantly in the last 400 years, so we should not attribute the LIA to the sun (however convenient it might be).’

    ‘The solar output during the Maunder Minimum was what it is right now, today.’ Both for TSI and for the magnetic field.’”

    I am curious about those statements.

    First, specifically, what does “significantly” mean? (To within what fraction of a percent?)

    It seems that while a very small upward trend in TSI (eg. 0.05%) might not be climatologically significant if it occurred for just a single decade (ie, if the total change were just 0.05%), it would nonetheless be climatologically significant if it continued for something on the order of a century or more (ie, if the overall change were 0.5%, for example)

    and directly related to #1)

    2) Can one be confident that TSI has remained constant to within 0.5% over the last several centuries?

    If so, what is the basis for such confidence?

  • Leif Svalgaard // November 3, 2007 at 2:30 am

    George: There are five lines of evidence forming the argument that the sun has not been any dimmer in the past. And by ’past’ I mean ’recent past’ [thousands, not billions of years - when the Earth was formed, the sun was 25% dimmer; it has slowly increased in brightness and will continue to do so over billions of years].
    Line 1;
    The Total solar Irradiance (TSI) does have several sources. The first and most important is simply the temperature in the photosphere. The hotter the sun, the higher the TSI. Some spectral lines are VERY sensitive to even minute changes in temperature. Livingston et al. has very carefully measured the line depth of such temperature-sensitive lines over more than 30 years spanning three solar cycles [Sun-as-a-Star Spectrum Variations 1974-2006, W. Livingston, L. Wallace, O. R. White, M. S. Giampapa, The Astrophysical Journal, Volume 657, Issue 2, pp. 1137-1149, 2007, DOI; 10.1086/511127]. They report [and I apologize for the somewhat technical turn my argument is taking, but if you really want to know, there is no avoiding this], “that both Ca II K and C I 5380A intensities are constant, indicating that the basal quiet atmosphere is unaffected by cycle magnetism within our observational error. A lower limit to the Ca II K central intensity atmosphere is 0.040. This possibly represents conditions as they were during the Maunder Minimum [their words, remember]. Within our capability to measure it using the C I 5380A line the global (Full Disk) and basal (Center Disk) photospheric temperature is constant over the activity cycles 21, 22, and 23″. I have known Bill Livingston [and White] for over 35 years and he is a very careful and competent observer, so I trust his result fully.
    Line 2;
    Since the 1960 we have known that the sun’s surface oscillates up and down [with typical periods of ~5 minutes]. These oscillations are waves very much like seismic waves in the Earth [caused by earthquakes] and just as earthquake seismic waves can be used to probe the interior of the Earth, the solar waves be used to probe the solar interior. There are millions of such solar waves at any given time and there are different kinds (called ’modes’) of waves. The solar p-modes are acoustic [sound waves] modes. You can imagine a frequency increase with an increasing magnetic field, due to the increase in magnetic pressure raising the local speed of sound near the surface where it is cooler and where the p-modes spend most of their time. Of course one can also imagine higher frequencies may result from an induced shrinking of the sound cavity and/or an isobaric warming of the cavity. Another kind is the solar f-modes that are the eigenmodes of the sun having no radial null points [i.e. asymptotically surface waves; again I apologize for the technical mumbo-jumbo]. From the solar cycle variations of p- and f-modes [and we have now enough data from the SOHO spacecraft to make such a study] we now have an internally consistent picture of the origin of these frequency changes that implies a sun that is coolest at activity maximum when it is most irradiant. Now, how can that be? How can a cooler [overall, including the cooler sunspots, for instance, as the temperature of the non-magnetic areas of the sun didn’t change {see line 1 above}] sun radiate more? It can do that, if it is bigger! The change in the radius of the Sun from minimum to maximum is about 1 km. Goode and Dziembowski (Sunshine, Earthshine and Climate Change I. Origin of, and Limits on Solar Variability, by Goode, Philip R. & Dziembowski, W. A., Journal of the Korean Astronomical Society, vol. 36, S1, pp. S75-S81, 2003) used the helioseismic data to determine the shape changes in the Sun with rising activity. They calculated the so-called shape asymmetries from the seismic data and found each coefficient was essentially zero at activity minimum and rose in precise spatial correlation with rising surface activity, as measured using Ca II K data from Big Bear Solar Observatory. From this one can conclude that there is a rising corrugation of the solar surface due to rising activity, implying a cooler and smaller active sun, whose increased irradiance is totally due to activity induced corrugation, that makes the sun a better radiator [that is why radiators have ribs]. This interpretation has been recently observationally verified by Berger et al. (Berger, T.E., van der Voort, L., Rouppe, Loefdahl, M., Contrast analysis of Solar faculae and magnetic bright points. Astrophysical Journal, vol. 661, p.1272, 2007) using the new Swedish Solar Telescope. They have directly observed these corrugations. Goode & Dziembowski conclude that the Sun cannot have been any dimmer, on the time steps of solar evolution, than it is now at activity minimum.
    Line 3;
    Foukal et al. (Foukal, P., North, G., Wigley, T., A stellar view on solar variations and climate. Science, vol. 306, p. 68, 2004) point out the Sun’s web-like chromospheric magnetic network (an easily visible solar structure seen through a Ca II K filter) would have looked very different a century ago, if there had been a significant change in the magnetic field of the sun supposedly increasing TSI. However, there is a century of Mt. Wilson Solar Observatory Ca II K data which reveal that the early 20th century network is indistinguishable from that of today.
    Line 4;
    Svalgaard & Cliver have recently (A Floor in the Solar Wind Magnetic Field, by L. Svalgaard and E. W. Cliver, The Astrophysical Journal, vol. 661, L203–L206, 2007 June 1, 2007) shown that long-term (∼130 years) reconstruction of the interplanetary magnetic field (IMF) based on geomagnetic indices indicates that the solar wind magnetic field strength [and thus that of the sun itself, from which the IMF originates] has a “floor,” a baseline value in annual averages that it approaches at each 11 yr solar minimum. In the ecliptic plane at 1 AU [at the Earth], the IMF floor is ∼4.6 nT, a value substantiated by direct solar wind measurements and cosmogenic nuclei data. We identify the floor with a constant (over centuries) baseline open magnetic flux. Solar cycle variations of the IMF strength ride on top of the floor. They point out that such a floor has implications for (1) the solar wind during grand minima — we are given a glimpse of Maunder minimum conditions at every 11 yr minimum; (2) current models of the solar wind — both source surface and MHD models are based on the assumption, invalidated by the Ulysses spacecraft, that the largest scale fields determine the magnitude of the IMF; consequently, these models are unable to reproduce the high-latitude observations; and (3) the use of geomagnetic input data for precursor-type predictions of the coming sunspot maximum — this common practice is rendered doubtful by the observed disconnect between solar polar field strength and heliospheric field strength [the wrong prediction by the NASA panel for cycle 23 was based on this precursor, and the prediction {of a high cycle} by one half of the panel for cycle 24 is also partly based on this]. The constancy of the IMF also has implications for the interpretation of the Galactic cosmic ray flux.
    Line 5;
    But maybe it is the Ultraviolet flux that varies and affects the stratospheric ozone concentration and thereby influences the climate. I have in (Calibrating the Sunspot Number using the “Magnetic Needle”, L. Svalgaard; CAWSES News, 4(1), 6.5, 2007) pointed out that the amplitude of the diurnal variation of the geomagnetic Y-component is an excellent proxy for the F10.7 radio flux and thus also for the EUV flux (more precisely, the FUV, as the Sq current flows in the E layer). There is a weak trend in the amplitude of 10% since the 1840s that can be understood as being due to an increase of ionospheric conductance resulting from the 10% decrease of the Earth’s main field. Correcting for and removing this trend then leads to the conclusion that (as for the IMF) there seems to be a “’floor’” in rY and hence in F10.7 and hence in the FUV flux, thus the geomagnetic evidence is that there has been no secular change in the background solar minimum EUV (FUV) flux in the past 165 years.

    Direct measurements (although beset by calibration problems) of the Total Solar Irradiance (TSI) from satellites have only been available for 30 years and indicate that solar irradiance increases with solar activity. Correlating mean annual TSI and sunspot numbers allows one to estimate the part of TSI that varies with the sunspot number. If TSI only depends linearly on the sunspot number then irradiance levels during the Maunder Minimum would be similar to the levels of current solar minima. But TSI is a delicate balance between sunspot darkening and facular brightening, and although both of these increase (in opposite directions) with increasing solar activity, it is not a given that there could not be secular variations in the relative importance of these competing effects. Several earlier reconstructions of TSI, reviewed in Fröhlich, C. & J. Lean (Solar Radiative Output and its Variability; Evidence and Mechanisms, Astron..& Astrophys. Rev., 12(4), 273, 2004, Doi;10.1007/s00159-004-0024-1.[6] all postulate a source of long-term irradiance variability on centennial time scales. Each group of researchers have their own preferred additional source of changes of the “background” TSI, such as evidence from geomagnetic activity, open magnetic flux, ephemeral region occurrence, umbral/penumbral ratios, and the like. The existence of “floors” in IMF and FUV over ~1.6 centuries argues for a lack of secular variations of these parameters on that time scale. The five lines of evidence discussed above suggest that the lack of such secular variation larger than about 0.2 W/m^2 undermines the circumstantial evidence for a “hidden” source of irradiance variability and that there therefore also might be a floor in TSI, such that TSI during Grand Minima would simply be that observed at current solar minima. This obviously has implications for solar forcing of terrestrial climate. At the same time, the apparent constancy of the heliospheric open magnetic flux have implications for mechanisms that invoke influence on climate by cosmic rays.

    Last: the evidence presented here is still being debated and the dust has not settled yet. In a sense you are watching science in the making.

    Very last: to show ignorance outside one’s field is not embarrassing [at opposed to if it had been within one's field!]. Doing science is a continual learning process. That process can be a frustrating one when encumbered by patronizing, sarcasm, arrogance, ad-homs, etc. If somebody asked me to explain something in my field I would be [almost:-) ] infinitely patient and do my very best in answering. If my explanation in spite of my best effort does not satisfy the well-intentioned questioner, I would consider it my failing and not his.

  • ks // November 4, 2007 at 7:45 pm

    Dr. S

    It is embarassing to make a claim like “since we don’t know what NC are nor model NC, how can we say that there are no NC for CW?” when natural causes have been modeled. My own advice would be to not claim something has not been done in another field without first looking to see if that is indeed true.

    You should look at FAQ 9.2 (page 702) “Can the warming of the 20th century be explained by natural variability?” with the figure comparing modeled natural causes to observed temperatures. You should probably read the full chapter 9, “Understanding and Attributing Climate Change” with the relevant section to your work, “Understanding Pre-Industrial Climate Change”

  • Leif Svalgaard // November 5, 2007 at 1:32 am

    As I read chapter 9.2, it is concerned with radiative forcing:
    From the FAQ:
    9.2 *Radiative* Forcing and Climate Response
    In this section, we review the estimated ranges of forcing over the last 150 years
    variability in *solar* forcing
    This yields an approximate net *radiative* forcing of –1.63 W m–2 between the late Maunder Minimum and the present

    To me (and again I would like to be educated on this, but the FAQ seems clear - but maybe I’m missing something) the -1.63 Wm-2 is a *solar* change. Otherwise it would not make sense or be misleading to tie it to the Maunder Minimum.

    By NC, I clearly meant NCs that are not solar or not related to a decreased solar input. I made a clear distinction between solar causes, natural other than solar, and human causes.

    As evidence is mounting that the solar output, both in visible light, FUV, solar wind, and magnetic flux during the M.M. probably was just was it is right now, today, the causes of the LIA have to be other than solar, and those other are the NC I was referring to. If you remove the solar aspect from the modelling, what is left? That was my question. And how is that modelled?
    And I’m not the slightest embarrassed (maybe like the little boy saying that the emperor had no clothes)

  • Steve Bloom // November 5, 2007 at 2:44 am

    (Please delete miskeyed prior comment. Thanks.)

    Thanks for that thorough exposition, Leif. I notice that a new effort from Scafetta & West appeared in GRL last week, so you’re guaranteed a hostile audience of at least two!

    What we’re left with, I suppose, are:

    –Tsonis’ idea about periodic behavior of the large-scale clinate oscillations.

    – Ruddiman’s proposal about anthropogenic vegetations changes.

    – Volcanos.

    – Errors in the proxy record that make variability look greater than it really was.

    Anything else?

    In any case I think your presentation will be met more with interest than irritation.

  • Leif Svalgaard // November 5, 2007 at 3:28 am

    Steve Bloom “I notice that a new effort from Scafetta & West appeared in GRL last week.”

    I don’t see it. Precise reference ?

  • Gareth // November 5, 2007 at 9:33 am

    If I’m on the same page, Dr S is effectively suggesting that climate sensitivity (to CO2 and other factors) is higher than currently thought - because change that is ascribed to solar variation is not (which is the main reason why Ruddiman’s hypothesis is considered outside the mainstream, IIRC).

    So, if the warming over the first half of last century were due to GHGs, where does that leave us today? With a bad case of global dimming, perhaps…

  • Leif Svalgaard // November 5, 2007 at 1:38 pm

    Gareth: “climate sensitivity (to CO2 and other factors) is higher than currently thought”
    Not necessarily to CO2 since CO2 was not so much an issue in previous coolings and warmings.
    My real issue is the many ’successful’ models that incorporate (likely non-existing) solar activity. My point is that the system does not seem to be so well understood as commonly thought and that that ought to give pause before we talk about what we KNOW, about, “consensus”, about “overwhelming” support for this or that, etc.

  • ks // November 5, 2007 at 3:32 pm

    FAQ 9.2 is on page 702. Section 9.2 is on page 670. The FAQ is not the same as the section… I’m beginning to wonder if you’re intentionally being difficult.

    “If you remove the solar aspect from the modelling, what is left? That was my question. And how is that modelled?”

    The FAQ mentions natural internal process like El Nino and natural external process like volcanic activity and radiative forcings. If you want a more specific answer to the questions, you’ll have to look up the papers in the reference section. IMO, a true scientist would look for the answer, rather than ask it in a way that assumes it hasn’t been done and effectually muddy the waters.

    The conclusion is that when you remove human inducec changes in greenhouse gas concentrations, the models fail to reproduce the observed late 20th century increase in global temp on a continental scale. The models with human induced changes also demonstrate troposphere warming w/ stratosphere cooling. It seems that the FAQ concludes with a statement that you are in agreement with, “The estimated climate variability caused by natural factors is small compared to the strong 20th-century warming.”

    I’m not sure that your emperor’s clothes analogy was accurate. And I think what ought to give you pause before talking about what we KNOW about, “consensus”, about “overwhelming” support for this or that, etc. is actually reading what is known in other field BEFORE making judgements about what is known. Previously you assumed we didn’t know enough to attribute the rise in CO2 to human activities… then tamino pointed you to the work by isotope chemists. I would think that would be enough for you to think to yourself, hmmm maybe I haven’t been keeping up with the body of knowledge and I should become aware, do some reading, before professing assessments on the state of current knowledge. But nope, you keep spouting them off. And that is what should be embarassing. Most scientists are aware that they cannot assess areas in which they are ignorant. But that does not appear to be stopping you.

  • Leif Svalgaard // November 5, 2007 at 4:03 pm

    ks: I go to the IPCC website and what looks to me as the FAQ: ttp://www.ipcc.ch/about/faq.htm

    This is what I get:
    About IPCC
    Frequently asked questions
    Organization chart
    IPCC Bureau
    IPCC Secretariat &

    Fact sheets about the IPCC process and activities
    Introduction Arabic | Chinese | English | French | Spanish | Russian
    Membership - Who is who in the IPCC Arabic | Chinese | English | French | Spanish | Russian
    Procedures - How IPCC reports are prepared Arabic | Chinese | English | French | Spanish | Russian
    Ongoing IPCC Activities Arabic | Chinese | English | French | Spanish | Russian
    Further information and text of IPCC procedures.

    User Guide to the IPCC Web site
    Where do I find out about the scientific basis for climate change?
    Where do I find out about climate impacts, adaptation and vulnerability?
    Where do I find out about climate change mitigation?
    Where do I find a synthesis of the latest findings on climate change?
    Where do I find out more specific information about:

    - emission scenarios
    - regional impacts of climate change
    - land use, land-use change, and forestry
    - methodological and technological issues in technology transfer
    - aviation and the global atmosphere

    Now I try to find your p.702. Naively, I thought that the 9.2 I find on the IPCC FAQ site is the FAQ 9.2. I agree that it would be good to be on the same page, so give me some constructive help here.

    And note that the “natural causes” mentioned by the IPCC, I split into two: 1) solar causes [SC], and 2) other natural causes [NC]. Since the FAQ does not [?] do that, we have to entangle the SC and the NC ourselves. This is what I’m trying to do. And BTW, you need to do something about the tone of your posts.

  • Leif Svalgaard // November 5, 2007 at 4:53 pm

    Re FAQ in AR4:
    I found what you were referring to:
    FAQ 9.2: Can the Warming of the 20th Century be
    Explained by Natural Variability? ……………………. 702

    Note that I’m concerned with the difference between the LIA and now, so the “20th Century” is not of immediate help.

    Anyway, the FAQ of the AR4 is clearer on the solar question. I quote:

    2.7.1.2 Estimating Past Solar Radiative Forcing
    2.7.1.2.1 Reconstructions of past variations in solar irradiance.
    Long-term solar irradiance changes over the past 400 years may be less by a factor of two to four than in the reconstructions employed by the TAR for climate change simulations. Irradiance reconstructions such as those of Hoyt and Schatten (1993), Lean et al. (1995), Lean (2000), Lockwood and Stamper (1999) and Solanki and Fligge (1999), used in the TAR, assumed the existence of a long-term variability component in addition to the known 11-year cycle, in which the 17th-century Maunder
    Minimum total irradiance was reduced in the range of 0.15% to 0.3% below contemporary solar minima. The temporal structure of this long-term component, typically associated with facular evolution, was assumed to track either the smoothed amplitude of the solar activity cycle or the cycle length. The motivation for adopting a long-term irradiance component was three-fold.
    Firstly, the range of variability in Sun-like stars (Baliunas and Jastrow, 1990), secondly, the long-term trend in geomagnetic activity, and thirdly, solar modulation of cosmogenic sotopes,
    all suggested that the Sun is capable of a broader range of activity than witnessed during recent solar cycles (i.e., the observational record in Figure 2.16). Various estimates of the
    increase in total solar irradiance from the 17th-century Maunder Minimum to the current activity minima from these irradiance
    reconstructions are compared with recent results in Table 2.10.
    Each of the above three assumptions for the existence of a significant long-term irradiance component is now questionable. A reassessment of the stellar data was unable to recover the original bimodal separation of lower calcium (Ca) emission in non-cycling stars (assumed to be in Maunder-Minimum type
    states) compared with higher emission in cycling stars (Hall and Lockwood, 2004), which underpins the Lean et al. (1995) and
    Lean (2000) irradiance reconstructions. Rather, the current Sun is thought to have ‘typical’ (rather than high) activity relative to other stars. Plausible lowest brightness levels inferred from
    stellar observations are higher than the peak of the lower mode of the initial distribution of Baliunas and Jastrow (1990). Other studies raise the possibility of long-term instrumental drifts in historical indices of geomagnetic activity (Svalgaard et al., 2004), which would reduce somewhat the long-term trend in the Lockwood and Stamper (1999) irradiance reconstruction.
    Furthermore, the relationship between solar irradiance and geomagnetic and cosmogenic indices is complex, and not necessarily linear. Simulations of the transport of magnetic flux
    on the Sun and propagation of open flux into the heliosphere indicate that ‘open’ magnetic flux (which modulates geomagnetic activity and cosmogenic isotopes) can accumulate on intercycle time scales even when closed flux (such as in sunspots and faculae) does not (Lean et al., 2002; Y. Wang et al., 2005).
    A new reconstruction of solar irradiance based on a model of solar magnetic flux variations (Y. Wang et al., 2005), which does not invoke geomagnetic, cosmogenic or stellar proxies,
    suggests that the amplitude of the background component is significantly less than previously assumed, specifically 0.27 times that of Lean (2000). This estimate results from simulations of the eruption, transport and accumulation of
    magnetic flux during the past 300 years using a flux transport model with variable meridional flow. Variations in both the total flux and in just the flux that extends into the heliosphere (the
    open flux) are estimated, arising from the deposition of bipolar magnetic regions (active regions) and smaller-scale bright features (ephemeral regions) on the Sun’s surface in strengths and numbers proportional to the sunspot number. ”

    and on and on. All this is supposedly well-known
    to ‘ks’ and others, and need perhaps not be repeated here. What is happening is that the very latest research (after the AR4 was finalized) seems to point to an even lower long-term change, to the point where it may be that there has been no change at all. This means that all the models and simulations that incorporate such assumed changes and find good agreements are now in doubt, and that the whole edifice is crumbling a bit.

  • Leif Svalgaard // November 5, 2007 at 5:06 pm

    The model of Solanki et al has been referred to in these postings. Permit me to comment on that:
    The Solanki et al. [2002] (see also Solanki, Schüssler, and Fligge, 2000) open flux model was developed in order to account for the doubling of the coronal magnetic field reported by Lockwood et al. [1999]. In this model, the open flux is a given fraction of the total magnetic flux over the Sun, which in turn is the sum of the flux from active regions (that falls to near zero at solar minimum), the flux from ephemeral regions, and the network flux. The free parameters of the model were adjusted in order to match the relative amplitudes of the cyclic flux to the doubling of the open flux reported by Lockwood et al. [1999], even to the point of discounting observational evidence (from Harvey, 1994) concerning the variation of the ephemeral flux [see Solanki et al., 2002, p. 710).

    The Lockwood et al. [1999] reconstruction has been superceded by Rouillard, Lockwood [yeah, same Lockwood] , and Finch [2007] which published an HMF (heliomagnetic field) time series that agrees substantially better with that of Svalgaard and Cliver [2005] than with that of Lockwood et al. [1999] and the net result is the much reported “doubling of the open magnetic flux in the last 100 years” simply did not happen. All that is left is general trend following the sunspot number which peaked during cycle 19 in 1958. The HMF right now during cycle 23 is just what it was 107 years ago during cycle 13.

  • Hank Roberts // November 5, 2007 at 5:21 pm

    Guys, please consider later readers who won’t know the context, give full URLs when available; else a proper citation to for example a PDF file source and page number.

    I know it’s incredibly tedious to do this. It’s also necessary to be understood.

    Now, when someone does NOT give an adeqate link or cite or pointer, we can fall back on teh Google, thus:

    http://www.google.com/search?q=IPCC+FAQ+9.2

    You can find a lot of things that _might_ be what KS is referring to. Too many, unfortunately.

    So, please, gentlemen. Cites. For the rest of us trying to follow along.

  • Steve Bloom // November 5, 2007 at 8:08 pm

    Responding to Leif and inspired by Hank, I went back and found the new Scafetta and West paper, which it turns out was in JGR (not GRL as I had misremembered).

    So, Hank, what about when someone responds with a link only?

  • Hank Roberts // November 5, 2007 at 8:45 pm

    > when someone responds with a link only

    Sometimes that’s enough, with relevance to some recent question.

    Sometimes more help will be needed at a linked page. The IPCC for example changes their links when they update documents (direct links to specific docs eventually break) and asks people to link to the FAQ index, so for that one, it helps new people if it’s explained as well as linked.

  • Leif Svalgaard // November 5, 2007 at 11:27 pm

    Scafetta & West 2007 uses and compares the TSI reconstructions by Lean 2000 and Wang et al. 2005. Lean’s is pretty much ruled out as the secualr increase since the M.M. is much too large. Wang’s has no secular change [check the minima values] up to 1900, but then takes off during the 20th century, largely based on the Lockwood open flux doubling. Since not even Lockwood believes the doubling any longer, there is no reason for Wang and us to believe in it either, and the large increase [S&W, Figure 3] in TSI during the 20th century is simply not there. Therefore the solar influence is also not there. So, now we two things to explain:
    1) the warming during 20th century, and
    2) the cooling during the LIA
    None of which are caused by the sun.
    So, we invoke Natural [other than solar! other than solar! other than solar! other than solar!] Causes [NC] for the cooling and Human causes [HC] for the warming. Doesn’t sound right to me.

  • tamino // November 6, 2007 at 12:28 am

    So, we invoke Natural [other than solar! other than solar! other than solar! other than solar!] Causes [NC] for the cooling and Human causes [HC] for the warming. Doesn’t sound right to me.

    That’s because it’s a complete mischaracterization of the present state of climate science.

    We invoke natural causes before the industrial revolution and human *plus* natural causes during the industrial age. Both can cause both warming and cooling. Example: much of the ~1920-1940 warming is due to an unusual lull in volcanic activity, while the main cause of *cooling* (more properly, the lack of warming) from ~1945-1975 is human: tropospheric aerosols from industrial activity.

  • Leif Svalgaard // November 6, 2007 at 12:52 am

    So, what caused the LIA?

  • ks // November 6, 2007 at 1:55 am

    Apologies to tamino for this being way off-topic of the original post.

    http://www.realclimate.org/index.php/archives/2004/11/little-ice-age-lia/langswitch_lang/in

    “The attribution of the term [LIA] at regional scales is complicated by significant regional variations in temperature changes due to the the influence of modes of climate variability such as the North Atlantic Oscillation and the El Nino/Southern Oscillation.”

  • Leif Svalgaard // November 6, 2007 at 1:58 am

    “complete mischaracterization of the present state of climate science.”

    I presume that the latest paper by Scafetta & West [Scafetta & West, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, D24S03, doi:10.1029/2007JD008437, 2007; peer-reviewed in the relatively respected JGR] represents as least some aspect of the present state of climate science.

    They note:
    “[33...] The solar-induced temperature signals [essentially derived from TSI] are consistently better correlated with MOBERG05 than with MANN03. Note that the above conclusion is evidently suggested by the good pattern correspondence observed in Figures 5b and 6b between MOBERG05 and the PTM solar signatures covering all four centuries. The pattern correspondence include those during the Maunder (1645–1715) and Dalton (1795–1825) minima, the cooling between 1860 to 1910, the warming from 1910 to 1950–1960, the cooling afterward until 1975 and the warming since 1975.”.

    I.e. all the major features of climate change seem to be accounted for in large part by solar influence. If we take away the solar aspect, there is basically no explanation for the variations [except possibly the very latest warming]. This is what I mean by the unknown natural causes {that are not solar}. My point (repeatedly stated) is that it is not clear what is going on so that it is false to state that “the science is clear”, “we have a pretty good idea”, etc.

  • Steve Bloom // November 6, 2007 at 2:05 am

    Hmm, it sounds like it’s a good thing for S+W that they have other work on which to base their reputations.

    Anyway, on a conceptual level I don’t see the issue. With solar zeroed, what do we really have during interglacials? Very slight Milankovitch trends, volcanos, and anthro aerosols/soot/GHGs (+/- any Tsonis-type effect). Given that list, is it so amazing that the natural is cooling and the anthro is warming?

    IIRC part of what’s gone on with modeling of the last millenium is that the solar stuff was made part of the baseline and used to infer the volcanic effects. If so, being able to discount solar influences may help to calirify things greatly. Very likely there are modelers reading this, so I’m sure we would all appreciate it if one of them would speak up.

    [Response: Volcanic effects are estimated from signs of volcanic activity in ice cores; as far as I know paleotemperature estimates are not used to estimate their magnitude. Anybody know more?]

  • Leif Svalgaard // November 6, 2007 at 2:35 am

    ks: “attribution of the term [LIA] at regional scales”

    Obviously if one denies the existence of variations [Roman Warming, MWP, LIA, etc] on a global scale and says that those were just regional fluctuations then there is no problem whatsoever with some unknown Natural Causes. This, of course, also means that “the good pattern correspondence observed in Figures 5b and 6b between MOBERG05 and the PTM solar signatures covering all four centuries. The pattern correspondence include those during the Maunder (1645–1715) and Dalton (1795–1825) minima, the cooling between 1860 to 1910, the warming from 1910 to 1950–1960, the cooling afterward until 1975 and the warming since 1975.” that is promoted by Scafetti and West is just spurious [which BTW I think it is, regardless].

    But then the alarmists should stop using the LIA as a bogeyman for “planet in peril” agitation.
    And all the ‘agreements’ should not be used as indications that we know what we are talking about.

  • tamino // November 6, 2007 at 3:23 am

    Regarding Scafetta & West, I think we both know that peer review is a necessary but not sufficient condition for quality results, and that quite a bit of real garbage makes it into some of the most reputable journals. I’d say they’re “rogues” in the climate science community, and some of the analyses I’ve seen from them are, frankly, highly questionable. For example, in studying climate sensitivity to the solar cycle they start with some spectral analysis, then attribute all of the signal power in an entire *octave* of the spectrum to the 11-year solar cycle, while attributing all the signal power in the neighboring octave to the 22-year cycle, completely ignoring the spectral response to the (very red) noise. From a time series perspective, this seems to me to be utter nonsense. They seem to want to attribute vastly more climate change to solar variability than all but a handful of researchers. Their data analyses are, in my opinion, simply not credible, and their results seem to me to be motivated more by a desire to make the numbers fit their pet theory than to make theory fit the numbers. RealClimate has discussed some of their work here and here.

    Regarding the state of the science in general, it’s a mischaracterization to suggest that anyone in the know claims “the science is clear” with regard to paleoclimate. There isn’t even agreement on how big the MWP and LIA are, and whether or not they’re regional, hemispheric, or global; compare the Mann & Jones (2003) temperature reconstruction to the Moberg (2005) reconstruction. According to Mann & Jones, the difference in centennial-scale global temperature from MWP to LIA is less than 0.15 deg.C, according to Moberg the northern-hemisphere difference is more like 0.7 deg.C.

    Where the science *is* clear is this: greenhouse gases cause warming, the climate impact from man-made GHGs is substantial, and the human influence will get a lot bigger as GHG emissions continue to accumulate in the atmosphere, leading to global warming such as the earth has not experienced in thousands of years. When people (especially on blogs) say the science is settled, that’s what they mean (except for the substantial number who are talking out of their *****), and they’re usually saying it to refute those who claim that global warming isn’t happening at all, or that human activity has no substantial effect.

    I’ve never before even heard it suggested that the LIA is a bogeyman for “planet in peril agitation.” When I hear about the LIA in climate discussions, it’s almost always someone who denies anthropogenic global warming, and exaggerates the LIA way out of proportion in order to suggest that the warming we’re seeing today is no larger than changes we’ve seen on similar time scales in the recent past.

    Referring to those of us who advocate strong action to mitigate global warming as “alarmists” is a value judgement, one I disagree with.

  • Leif Svalgaard // November 6, 2007 at 4:21 am

    tamino: “quite a bit of real garbage makes it into some of the most reputable journals”.
    In order to calibrate your perspective on this, could you direct me to a recent paper that is not garbage? One that you think is good [and that possibly reflects your own thinking].

  • tamino // November 6, 2007 at 3:15 pm

    I generally don’t consider papers garbage even if I disagree with the conclusions, as long as the analysis is sound and the argument is coherent.

    In most fields garbage papers get very little attention, they die a quiet death. But in climate science they sometimes get more attention than anything of quality, because they are heralded by people with political motivation to deny that global warming is real or man-made; senator Inhofe does this a lot.

    As for good stuff, I’m not a climate scientist so I can only relate what I’ve enjoyed, which includes a review article from not too long ago, Houghton 2005, Global Warming, Rep. Prog. Phys., 68, 1343–1403. Something more recent which I really enjoyed is Ditlevsen et al. 2007, The DO-climate events are probably noise induced: statistical investigation of the claimed 1470 years cycle, Clim. Past, 3, 129-134 (www.clim-past.net/3/129/2007). I’m not sure I agree with it completely, but the analysis is nicely done and the whole thing really resonates with my inherent skepticism whenever anyone declares behavior “cyclic.”

    As for the work by Scafetta & West, I’m not the only one who regards it as dubious; you really should read the RealClimate commentary linked to in my previous comment.

  • JamesG // November 6, 2007 at 6:01 pm

    Seems to me Scafetta gave a very robust defense in the Realclimate comments. Very interesting indeed. Clearly the realclimate team don’t like the Moberg reconstruction (presumably as it disagrees with the Mann reconstruction in having a MWP and LIA), they don’t like the idea that the sun influences climate despite admitting that multiple books and papers have concluded exactly that (including NASA several times I might add), they don’t like that Scafetta points out problems in the GISS model and they hate that Scafetta has matched TSI to Moberg so much that they rushed to criticize it without apparently even understanding fully what he did. Gavin further admits that his solar and aerosol forcings are just “best guesses” based purely on runs of his own climate model. All very scientific! It was ever thus.

    Are we regressing here - I thought there was a consensus forming about natural effects and climate change prior to 1970?

  • Steve Bloom // November 6, 2007 at 8:04 pm

    JamesG, vehement shouldn’t be mistaken for robust.

  • Leif Svalgaard // November 6, 2007 at 8:48 pm

    I never said that Scafetta & West were correct or that the paper was sound. On the contrary, I pointed out that they used TSI reconstructions that were way of of date and not in line with latest research. I have heard elsewhere [even in these august pages] that the simulations of 20th century climate that include the sharp increase of TSI during the first half of the century gave a very good match to observed temperatures, so S&W did not seem to be so far out of the mainstream. If there is such a wide spread in conclusions the experts cannot be said to have this thing nailed down, IMHO. And that was my point.

  • Leif Svalgaard // November 6, 2007 at 8:55 pm

    and who cares if a paper is garbage? as tamino points out, such papers simply die. Science is self-correcting [unless interfered with by politicians, Nobel Prize winners, evangelists, activists, and the like] and in due time all the crap is weeded out. And don’t tell me that there isn’t any time left, than we must act NOW to save the planet. If you do, that is alarmist to me.

  • Petro // November 6, 2007 at 11:14 pm

    Leif ejaculated:
    “And don’t tell me that there isn’t any time left, than we must act NOW to save the planet. If you do, that is alarmist to me.”

    You keep repeating that in your mind the global warming is a good thing and there is no need to worry about it.

    So how you feel those unfortunate, who live in the areas where changing climate causes unpredictable droughts and floods? How you feel for people living in countries like Bangladesh?

    To most ‘alarmists’ preventing futile human suffering is a moral imperative. Do you realize that?

  • Steve Bloom // November 7, 2007 at 12:41 am

    Scandinavian countries have liberal immigration policies, right? :)

    Leif, take it for what it’s worth, but my view is that we are already committed to paying some substantial costs, and that those costs will tend to increase as we continue to not implement solutions of the appropriate scale. In the relatively short-term, I’m not worried so much about the direct environmental impacts (with the possible exception of ocean acidification) as the consequences of things like the loss of the Tibetan-area glaciers. That could get very, very nasty, up to and including regional nuclear war.

    Longer term, one can imagine some pretty bad effects (of both kinds) arising from the GIS and WAIS melting even if it does take several hundred years.

    To run a significant risk of these kinds of outcomes is to fail to behave like a good ancestor.

    [Response: A thoughtful and civil expression of opinion... thanks.]

  • Steve Bloom // November 7, 2007 at 1:17 am

    Talk about serendipity: Moments after I posted I saw this just-released detailed study. I haven’t had a chance to more than glance at the text, but it seems to be a thorough albeit U.S.-centric attempt to analayze the foreign policy and security implications of AGW under several scenarios.

  • EliRabett // November 7, 2007 at 1:34 am

    They don’t die, they keep getting quoted as biblical truth on the INTERNET, something new that we have to get used to, which means the criticisms have to be posted and creep up high on the google ranking. Sorry Lief, it’s a brave new world.

  • EliRabett // November 7, 2007 at 1:37 am

    Land use changes, esp in the 19th century and somewhat into the 20th.

  • Steve Bloom // November 7, 2007 at 1:42 am

    From page 100 :

    ‘China’s top priority, quite simply, remains economic growth, with officials citing it as a “right” for developing countries. At the September 24, 2007 UN High-Level Event on Climate Change Foreign Minister Yang Jiechi framed his remarks by opening “climate change is an important development issue.” Last year, Chinese State Councilor Hua Jianmin also at least sought to deflect international pressure, making the converse argument that “economic development is not only a prerequisite for the subsistence and progress of human beings, but also a material foundation for the protection and improvement of the global environment.” Recently, however, China has begun to see the consequences of environmental damage generally and climate change specifically such as drought, crop shortages, and typhoons as rhreats to economic growth. A February 2007
    Lehman Brothers report cited estimates by Chinese researchers that environmental pollution in 2004 cost the Chinese economy 3.1 percent of GDP. At the end of 2006, the Chinese Ministry of Science and Technology claimed specifically that “global climate change has an impact on the nation’s ability to develop further.” Chinese concerns about the environment transcend the economy to social stability itself, a terrifying prospect for the Chinese leadership.

    ‘Thousands of Chinese have demonstrated across the country in riots such as the 2005 incidents in Huaxi village and in Xinchang that John Podesta and Peter Ogden previously discussed in this study. While these clashes were both narrowly over factory pollution, they raise the prospect that the Chinese people are willing to speak and act out over access to clean water. Chinese officials are aware of the threat warming presents. Earlier this year the deputy director of China’s office of Global Environmental Affairs in the Ministry of Science and Technology, Lu Xuedu, pointed out that river levels will decline while droughts and floods increase because of climate change, specifically warning that demand would outstrip the supply of water in western China by up to 20 billion cubic meters from 2010 to 2030. Qin Dahe, an expert at the Chinese Academy of Sciences, also recently raised the concern that glaciers on the Qinghai-Tibet plateau could shrink to 100,000 square kilometers by 2030 (from 500,000 in 1995), reducing the melting water that feeds many major rivers in Asia and jeopardizing the water supply for up to a billion people. Financial Times columnist Gideon Rachman put it best: “The government in Beijing faces a dilemma. Terrified of social unrest, it is reluctant to do anything that might slow economic growth—such as stopping the building of coal-fired power stations. Yet water shortages are already causing social unrest in the countryside and the water table is falling fast in Beijing.” Clearly what China is willing to do to mitigate or adapt to climate change will be shaped by economic pressures but its views are changing because climate change is now viewed as an economic problem and a threat to political stability.’

  • Leif Svalgaard // November 7, 2007 at 2:33 am

    I’m not quite alone in thinking that the threat to marine life is not so deadly as assumed:

    Riebesell (Riebesell, U. 2004. Effects of CO2 enrichment on marine phytoplankton. Journal of Oceanography 60: 719-729.2004) notes that “CO2-sensitive taxa, such as the calcifying coccolithophorids, should therefore benefit more from the present increase in atmospheric CO2 compared to the non-calcifying diatoms.”

    In a recent study, Fine and Tchernov (Fine, M. and Tchernov, D. 2007. Scleractinian coral species survive and recover from decalcification. Science 315: 18112007) Fine and Tchernov concluded that “corals might survive large-scale environmental change, such as that expected for the following century.” They’ve done it before (e.g. Medina, M., Collins, A.G., Takaoka, T.L., Kuehl, J.V. and Boore, J.L. 2006. Naked corals: Skeleton loss in Scleractinia. Proceedings of the National Academy of Science U.S.A. 103: 9096-9100), and they likely have the capacity do it again.

    Corals have been around for hundreds of millions of years.

  • Leif Svalgaard // November 7, 2007 at 3:00 am

    to Steve Bloom,

    I too worry about nuclear warfare [global not regional] but likely for very different reasons than you. Even if we wanted to curb emissions, we can’t. The U.S. will not give up squandering the Earth’s resources [John Kerry: "Oh, the SUV? It's not mine, I'm green, it belongs to my wife"]. If we try to force emission limits on nations that are industrializing [e.g. China, India - kill them farting cows] they will object and possibly violently. Humans do not co-operate when there is short-term advantages in not to. And then there is this: I recently had a discussion with a friend of mine who believes the Earth is 6000 years old and that all this debate about climate change is nuts because we live in the “end-times” and shall have “rapture” soon. He claimed that up to half of all Americans share his beliefs [to me it makes no difference if the percentage is 50, or only 35 or 40 - it is scary enough].

  • Dano // November 7, 2007 at 3:15 am

    Corals have been around for hundreds of millions of years.

    Sigh…

    Fortunately decision-makers are usually briefed by people who know what they are talking about, and are not briefed by those ignorant of natural science.,.

    The corals extant today have adapted to their surroundings only in the last few tens of thousands of years, none of which had CO2 ppmv levels as high as today, and certainly not at 1000 ppmv.

    HTH.

    Best,

    D

  • Steve Bloom // November 7, 2007 at 4:58 am

    Leif, the concern is about the loss of the reef eco-systems. The Fine and Tchernov abstract reads:

    “Anthropogenic-driven accumulation of carbon dioxide in the atmosphere and projected ocean acidification have raised concerns regarding the eventual impact on coral reefs. This study demonstrates that skeleton-producing corals grown in acidified experimental conditions are able to sustain basic life functions, including reproductive ability, in a sea anemone-like form and will resume skeleton building when reintroduced to normal modern marine conditions. These results support the existence of physiological refugia, allowing corals to alternate between nonfossilizing soft-body ecophenotypes and fossilizing skeletal forms in response to changes in ocean chemistry. This refugia, however, does not undermine the threats to reef ecosystems in a high carbon dioxide world.”

    So the coral species (presumably more than just the one) will survive to calcify another day, but in the short term the reefs and their vast associated ecosystems are toast.

    BTW, while there are certainly areas of climate science where there is disagreement among experts, coral studies isn’t one of them. Their uniform view is that we are looking at a disaster for the reefs.

    Coral scientists have a pretty good web presence. Coral Bones is a good place to start if you want more information.

  • dhogaza // November 7, 2007 at 5:00 am

    I’m not quite alone in thinking that the threat to marine life is not so deadly as assumed…

    Your essential argument seems to be …

    “If we change the environent, it will be to our benefit, no matter what we do”

    Interesting to me is the fact that you cherry-pick papers that support your position, regardless of what scientists in the field believe to be true.

    Your rap seems to be “those that deny consensus that have beliefs congruent with my right-wing beliefs must be true”.

    I’m not convinced.

  • dhogaza // November 7, 2007 at 5:04 am

    Even if we wanted to curb emissions, we can’t. The U.S. will not give up squandering the Earth’s resources

    Therefore, climate scientists must be wrong.

    Because, if they’re right, it doesn’t matter. Nothing will happen anyway.

    So you’ll invest yourself in the notion that they’re wrong.

    That about sums things up, right?

  • nanny_govt_sucks // November 7, 2007 at 5:10 am

    The corals extant today have adapted to their surroundings only in the last few tens of thousands of years, none of which had CO2 ppmv levels as high as today, and certainly not at 1000 ppmv.

    Dano, this appears to be a familiar meme of yours. Can you provide a reference for your claim? Obviously plants have some kind of genetic memory to a time when CO2 was at 1000+ppm. It doesn’t seem like such a stretch to believe that coral would too.

  • Heretic // November 7, 2007 at 5:25 am

    Corals have been around for a long time and recovered from various events through geologic ages. Humans were not around when that happened. Corals may very well be able to withstand the current climate change alone, depending on how far that change goes. Nobody knows how they’ll fare with that change compounded with the seemingly endless array of other pressures applied throughout the marine ecosystems.

  • Hank Roberts // November 7, 2007 at 10:02 am

    Yep. It’s, I’d say astonishing, but I guess I’m getting cynical — at least surprising to find someone going to such lengths to set out yet another version of the ‘we don’t know enough to decide what to do, so going on changing things faster than ever before is not irresponsible’ argument, in a limnological article of all places. He ends up with

    “In view of the inherent complexity of biological systems, including marine pelagic systems, it seems impossible at this point to provide a comprehensive and reliable forecast of large-scale and long-term biological responses to global environmental change. Any responsible consideration aiming to regulate or manipulate the earth system in an attempt to mitigate the green-house problem is presently hindered by the large gaps in our understanding … understanding the complex structure and regulation of the marine plankton, their responses to global environmental changes and the consequences thereof for marine biogeochemical cycling will be a major challenge …”

    Well, yes, except going to hell in a handbasket _is_ a decision to manipulate the environment, and slowing down isn’t indistinguishable from racing onward as a choice.

    This guy’s actually arguing that dissolving the shells off the shell-forming plankton won’t necessarily hurt them any, maybe they just accumulate the shells as a way of getting rid of waste material they don’t need and they’d rather be naked.

    Gott in himmel.

  • JamesG // November 7, 2007 at 10:04 am

    I wish people would stop repeating the canard about Bangladesh. They have floods because they are in a river delta. The floods are made much worse because they have removed the ground cover for farming and fuel. If we supplied them with fuel that would actually help the situation. This idea that extreme weather events are caused by global warming doesn’t even have any solid foundation - it is the epitome of alarmism. Droughts and floods can indeed be made worse by man but in far more direct ways than global warming and poverty reduction is by far the best cure. Also, I hate to hear people assuming that poverty in the 3rd world will be as bad 100 years from now. From where does all this pessimism stem? Shouldn’t we at least be trying to reduce poverty as a first step? Do you realize the extent of poverty in Europe 100 years ago and do you understand why they aren’t poor now? Poverty reduction also has the nice side-effect of population reduction. Point your bleeding heart to the right cause please.

  • JamesG // November 7, 2007 at 10:24 am

    BTW, those of us who are actual contact with India and China know that they are far more ambitious with regards to alternative energy than the West, for all our posturing. India and China are both planning a nuclear future with battery operated vehicles; primarily scooters. India, via Tata and BP (believe it or not) also have a huge solar cell plant which is one of the reasons solar power has dropped in price by 10 times in recent years. Also, you may not know but it is possible to get nuclear power without enriching Uranium, eg heavy water reactors such as CANDU which can actually use for fuel natural uranium, nuclear waste from other reactors, waste from nuclear weapons and (with some work) thorium. India and China are building these reactors now. But what are we doing in the West? Talking about carbon trading and carbon taxes!

  • Andrew Dodds // November 7, 2007 at 10:53 am

    Leif -

    Ironically, one of my undergraduate projects was looking at reef building organisims over the phanerozoic. During this time there have been several different types of reef building organism (Sponges, Molluscs, corals); the true hard corals being relatively recent. Mass extinction of reef building organisms and replacement with very different new reef-builders suggests that the habitat can be almost completely destroyed worldwide.

    So corals might survive (Or their niche will be refilled), but large coral reefs may well not.

  • Dano // November 7, 2007 at 2:44 pm

    Here is a good explanation of the ocean acidification issue.

    Best,

    D

  • Majorajam // November 7, 2007 at 3:45 pm

    Leif,

    In English dictionaries, you’ll find this word- credulous. While 35, 40, 50 would indeed be scary, you’ll find this claim was made by a believer, so perhaps not the best source. Though this does shed light on some other of the claims you seem to be buying. Do have a stock broker per chance?

  • Dano // November 7, 2007 at 4:27 pm

    Dano, this appears to be a familiar meme of yours. Can you provide a reference for your claim? Obviously plants have some kind of genetic memory to a time when CO2 was at 1000+ppm. It doesn’t seem like such a stretch to believe that coral would too.

    Any basic biology textbook.

    And your continued reliance on your belief that “plants” do just ducky at 1000 ppmv CO2 is clogging this comment thread.

    Best,

    D

  • dhogaza // November 7, 2007 at 5:41 pm

    Shouldn’t we at least be trying to reduce poverty as a first step?

    There’s that false dichotomy again.

    Of course we should continue to try to reduce poverty in the third world while we work to reduce future warming.

  • nanny_govt_sucks // November 7, 2007 at 6:18 pm

    Any basic biology textbook.

    Sorry Dano, but I’m going to have to ask you to be a little more specific. Which text book? What page?

    And your continued reliance on your belief that “plants” do just ducky at 1000 ppmv CO2 is clogging this comment thread.

    I’m simply replying to your unsupported claims that appear to be clogging these threads as well.

  • Lee // November 7, 2007 at 7:15 pm

    JamesG said:
    “I wish people would stop repeating the canard about Bangladesh.”

    17% of Bangladesh is less than 1 meter above sea level. More than 13 million people live in that area. A significant part of their rice harvest comes from that area.

    It is not a canard to point out that there would be (at least) a significant bad impact on Bangladesh to lose 17% of its land, and the homes of 13 million people, and a good chunk of its ag output, to a 1 meter sea level rise.

    Look at more than 1 meter, and the analysis becomes rapidly worse for Bangladesh.

  • Petro // November 7, 2007 at 7:42 pm

    JamesG claimed:
    “This idea that extreme weather events are caused by global warming doesn’t even have any solid foundation - it is the epitome of alarmism.”

    Look around, pal. Or look your tube. Your denialism is epitome of egocentric ignorance.

    Would you be curious enough, you could lift your veil of ignorance by starting here:
    http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch11.pdf

  • Dano // November 7, 2007 at 8:11 pm

    na_gs,

    Basic biology, Darwinian evolution and Mendelian genetics (along with recent work on genetic lineages) find that in unstable systems mutations occur that may or may not contribute to fitness, and certain traits may be expressed…anyway, I don’t have time to educate you in basic evolution. Enroll in an evolution class at your local junior college after you finish your BIOL and math prereqs.

    wrt your hand-waving about plants and higher CO2 ppmv fitness, you are incorrect and you don’t seem to want to get why. Plus, you don’t get it period. You don’t want to get it because it disagrees with your ideology.

    There are numerous factors at play over why most of the FACE experiments disagree with “your” assertion. Soil being limited in N is one of them, as well as soil moisture limitations and O3 interactions. Simple. We’re done, as I’m tired of correcting you and educating you. Go to college and take some natural science classes.

    Best,

    D

  • Petro // November 7, 2007 at 8:41 pm

    But Dano, how come you don’t tell us the books and page numbers for Darwinian evolution and Mendelian genetics?

    ;)

  • Dano // November 7, 2007 at 9:54 pm

    But Dano, how come you don’t tell us the books and page numbers for Darwinian evolution and Mendelian genetics?

    Would that The Google had a ‘wisdom’ button…

    ;o)

    Best,

    D

  • Hank Roberts // November 7, 2007 at 9:57 pm

    If you’re waiting til co2science says it before you believe it, you’ll wait a while.

  • nanny_govt_sucks // November 8, 2007 at 2:04 am

    Dano, you said:

    The corals extant today have adapted to their surroundings only in the last few tens of thousands of years …

    … and for that I am asking for a reference. I’m sure that a biology book will tell us that organisms evolve and adapt, but I wonder if they will tell us that that evolution and adatpation is limited to the last few tens of thousands of years of the species’ existence. Of course, I could be wrong. So I’ll wait for the reference.

    wrt your hand-waving about plants and higher CO2 ppmv fitness, you are incorrect

    Assertions. Gotta love ‘em.

    Soil being limited in N is one of them, as well as soil moisture limitations and O3 interactions.

    … none of which was I refering to in my post about optimal CO2 concentrations for plants. These are all red herrings of your creation, Dano. Soil nutrients, moisture, and O3 levels have nothing to do with the subject of the apparent “genetic memory” inherent in most plants.

  • Dano // November 8, 2007 at 3:58 am

    That was an ‘img src’ HTML, delete if not enabled

  • Hank Roberts // November 8, 2007 at 4:33 am

    “Genetic memory” is a religious idea, right? Goes with intelligent design, the idea that everything is made with a plan?

    Just checking if this is what you’re talking about, because it’s how the term is used by others.

  • JamesG // November 8, 2007 at 11:50 am

    Petro
    You link pointed me to long term climate projections. Note projections, not predictions and climate, not weather. Now read my words again. Maybe you can continue your search of IPCC documents to find the part where they state that no single weather event can be ascribed to global warming: which of course reflects the vast majority of scientific opinion. If you believe differently it is just your belief. Weather events in the past were in fact just as extreme and frequent, as confirmed by the records. Probably they seem more frequent to you because we are now informed about them more often. Mind you, if you get your science from the newspapers I can understand your confusion. However I don’t want to leave the impression that I don’t care for the 3rd world, I’m just trying to bring home that their real problems are here and now, not in 100 years time.

    Lee
    I share your concern about Bangladesh but they get huge floods quite regularly now, never mind in 100 years. Holland is largely below sea level now but they cope because they have money. That’s the point! The 1m you quote is a gradual change 100 years into the future. A lot can happen in 100 years and many of us are trying to work towards poverty not being an issue in Bangladesh then. 17% is actually a lower estimate than I thought but have you noticed the artificial towns being reclaimed from the sea in Dubai? If you now think - yes but they have the money to do it - then you are getting the picture.

  • JesusChristHimself // November 8, 2007 at 2:17 pm

    They built dikes to hold out a relatively stable ocean. It remains to be seen whether the Dutch would foolishly attempt to hold out an unstable ocean. Besides, that Dutch money would be better spent preventing aids in Africa than being spent on dikes to protect the rich.

  • Petro // November 8, 2007 at 2:17 pm

    JamesG said:
    “Weather events in the past were in fact just as extreme and frequent, as confirmed by the records.”

    Really? You have a pointer to those records?

  • Heretic // November 8, 2007 at 9:38 pm

    Talking about references, ngs, care to provide links to peer-reviewed papers on that “genetic memory” idea?

  • nanny_govt_sucks // November 9, 2007 at 1:38 am

    You can find my references in my post from “Oct 30th 2007 at 9:04 pm” earlier in this thread.

  • Dano // November 9, 2007 at 3:08 am

    They don’t back your assertion. Heretic is asking for evidence that backs your assertion.

    10-year old closed-chamber experiments are not the same as the vastly different results found in free air in soil.

    Apparently there is only one person on the planet who fails to make this connection. Truth is stranger than fiction.

    Best,

    D

  • Jamesg // November 9, 2007 at 10:52 am

    Petro
    I could give you lots of links but staying specific to Bangladesh and steering clear of “skeptic” data which you’d automatically reject, here is a nice summary:
    ftp://ftp.fao.org/docrep/fao/010/a1247e/a1247e00.pdf
    Neither max temps nor rainfall nor monsoon variability have actually increased since records began between the 50s and 60s. In fact natural variability is the dominant theme. The predicted GCM temperature rise (1.4C by 2100) indeed looks ridiculously pessimistic when set against the past records. Of course that isn’t discussed, they simply assume the GCM’s will be correct and predict the biggest problem under that scenario would be drought due to variable monsoon variability (controversial and pessimistic but never mind), not sea level rise. The booklet concentrates on adaptation to these changes which, as it turns out, is pretty sound practise for current problems too. Hence I fully support the funding of adaptation initiatives whlst keeping quiet about the pessimism involved - any improvement initiative at all is welcome. Of course I also support mitigation, mainly because fossil fuels are getting too expensive and have always been too dirty. So we’re not in disagreement about desired end results I hope, even when starting from different perspectives.

  • Petro // November 9, 2007 at 6:25 pm

    JamesG, would you have actually read the FAO booklet you linked and not just referred to the figures someone else gave to you, you would have realized that your assertions are completely bollocks.

    Just from preface: “A large percentage of the population is already to vulnerable to a range of natural hazards with increasing climate variability and climate change expected to aggravate the situation further by causing more frequent and intense droughts and increasing temperatures.” And so on.

    The reason why it is assumed the GSMs are correct is that if they do not take measures to accomondate the coming disaster, it will be even more severe for Bangladesh. GSMs are based on mainstream science, and it is always a good policy to base political decisions on science.

    You know, in Bangaladesh it is a matter of people’s life, not just some annoyance to stop driving SUVs.

  • Hank Roberts // November 9, 2007 at 8:23 pm

    Nan, if you believe the world was designed, that there’s an optimum temperature for plants, that there’s a “genetic memory” in the way the bible sites describe it — what you believe is your choice. But it does limit the sources you will accept as legitimate.

    If you are not coming from the intelligent-design point of view, then you should read some of the other work available to you that contradicts those ideas.

  • Hank Roberts // November 9, 2007 at 9:31 pm

    Nan, they say this guy’s book is “acclaimed” — but where? try looking for positive reviews, don’t rely on them as a good source for facts. They spin.
    http://www.co2science.org/scripts/CO2ScienceB2C/about/sab/wittwer.jsp

    Look further, just for example
    http://www.berkeley.edu/news/media/releases/2005/08/02_carbon.shtml

  • nanny_govt_sucks // November 9, 2007 at 10:21 pm

    Nan, if you believe the world was designed, that there’s an optimum temperature for plants, that there’s a “genetic memory” in the way the bible sites describe it — what you believe is your choice.

    Hank, just for your information, I really know when I’ve struck a nerve when I get these types of reactions to my posts. If you have to resort to painting me as a religious fundamentalist, industry funded or whatever, it just reveals that you’re completely out of ammunition, there’s a click-click-click sound and you’ve now thrown your revolver in my direction.

  • Dano // November 9, 2007 at 11:55 pm

    Note how na_gs has distracted away from the fact that the refs don’t back the assertion.

    This is the standard pattern.

    Best,

    D

  • nanny_govt_sucks // November 10, 2007 at 12:49 am

    Dano, what’s your reference for

    The corals extant today have adapted to their surroundings only in the last few tens of thousands of years …

    ?

  • Hank Roberts // November 10, 2007 at 12:53 am

    No, I’m not suggesting you play Russian Roulette — I’m saying when I look up the terms you’ve been using (”optimize” and “genetic memory”) I find the same thing you’ll find if you search for them.

    I’m asking — since you have been asking questions based on the assumption that plants have an optimum for growth, and that genetic memory exists — where you get these ideas?

    Evolution doesn’t optimize.
    “Genetic memory” isn’t documented.

    You believe these things.

    Why?

  • Hank Roberts // November 10, 2007 at 1:01 am

    On corals, just as an example of how to start looking, this may help — follow cites forward, for example, for more.

    The rate of change at present compared to the rates of change during the past is what’s worrisome.

    http://links.jstor.org/sici?sici=0094-8373%28198424%2910%3A1%3C48%3AGTATQE%3E2.0.CO%3B2-S&size=LARGE&origin=JSTOR-enlargePage
    http://www.sciencemag.org/cgi/content/short/301/5635/929

    http://biology.ucf.edu/~djenkins/courses/biogeography/Hewitt1996.pdf

  • Heretic // November 10, 2007 at 4:24 am

    I looked at the links in your earlier post, ngs, and nowhere saw the term “genetic memory.” It is still unclear to me what you mean exactly by that.

  • dhogaza // November 10, 2007 at 5:29 am

    ngs:

    Hank, just for your information, I really know when I’ve struck a nerve when I get these types of reactions to my posts. If you have to resort to painting me as a religious fundamentalist

    He didn’t say that (typical strawman). He asked if your belief in “genetic memory” was the same as that touted in biblical sites.

    His point being that this isn’t an idea found in science, only among fundies.

    You may believe them because you’re gullible and don’t know it’s fundie stuff, rather than being a fundie yourself.

    In other words, a purely innocent fall into pseudoscientific stuff by you.

    On the other hand …

    Well, you tell us which way it is?

    1. Non-fundie falling for fundie lies
    2. Fundie falling for fundie lies

  • nanny_govt_sucks // November 10, 2007 at 5:36 am

    Heretic, again, please see my post from “Oct 30th 2007 at 9:04 pm”. If you are still confused, try reading the post yet again.

  • JamesG // November 10, 2007 at 10:48 am

    Petro
    You are unbelievable. You asked for data as proof and I provided it. I linked that specific document so that you wouldn’t say it was skeptical and dismiss the data in it. The authors had the task of assessing worst case scenarios, not of assessing the science behind them. But even a cursory glance shows any reader that the GCM temperature projections are absurd. You say that’s mainstream science. I agree - but mainstream science is clearly overly pessimistic isn’t it? Even the notion that monsoons will be worse is not actually based on science but on a worst case scenario. Exactly the same would be assumed for global cooling projections.

    I hate SUV’s, but high fuel prices affect heating and food prices too. Many vulnerable people this Winter will have to choose between heating and eating. Can you spare a thought for them too? My original point was that in Bangladesh they are suffering, and will continue to suffer, because of poverty - not global warming. High fuel prices in fact hurt them further. Meanwhile the oil companies you despise are rolling in money.

  • Hank Roberts // November 10, 2007 at 3:57 pm

    Nan, we all did look. You cite to one book acclaimed by co2science, and one decade-old study, then write:

    > It would seem that plants
    > “remember” a time when CO2
    > concentrations were much higher,
    > does it not? Or is there some other
    > interpretation?

    And we’ve responded.

    There’s a straightforward interpretation from plant biology.

    There’s no evidence for plants “remembering” nor for an “optimum” temperature per that book.

    You’re assuming that greenhouse vegetable forcing techniques — selected strains of greenhouse tomatoes in cultivation may well do better with higher CO2 — somehow prove that the whole world would be better off with higher CO2.

    You’re saying there’s an optimum CO2 level and we’re below it now.

    Nothing supports this in what you’ve pointed to. You clearly believe it.

    Why?

  • Petro // November 10, 2007 at 4:43 pm

    JamesG wonder:
    ” but mainstream science is clearly overly pessimistic isn’t it?”

    Mainstream science is conservative, the most recent data is not incorporated into it. The trend has been, as time goes by, the mainstream climate science is assuming more serious consequences for global warming.

    Your opinion suggest you have some sort of conscience. What amazes me how you still can deny scientific reality in global warming.

    The povery in Bangladesh and elsewhere in the developing is definitely a problem to be solved.

    In the capitalistic market economy, the oil companies is fulfilling their role as long as the politicians allow it. I am not seeing any change in that respect for the coming years.

  • Heretic // November 10, 2007 at 6:22 pm

    I read and understood your post. However, you have no real explanation for the genetic part of the idea and your links do not say anything about it at all.
    Cattle grow faster when fed non-therapeutic doses of antibiotic. According to your theory, that would imply that their genes “remember” a time when they had antibiotics in their diet. That could easily be described as delirious nonsense.

  • Hank Roberts // November 11, 2007 at 2:43 am

    Nan, it _is_ p0ssible to intelligently design plants and optimize for particular conditions; the first work is just now being done in computer modeling, matching some actual experience:
    http://www.news.uiuc.edu/news/07/1109photosynthesis.html

    ——excerpt—–
    “By rearranging the investment of nitrogen, we could almost double efficiency,” Long said.

    An obvious question that stems from the research is why plant productivity can be increased so much, Long said. Why haven’t plants already evolved to be as efficient as possible?

    “The answer may lie in the fact that evolution selects for survival and fecundity, while we were selecting for increased productivity,” he said. The changes suggested in the model might undermine the survival of a plant living in the wild, he said, “but our analyses suggest they will be viable in the farmer’s field.”
    —–end excerpt—-

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