Open Mind


September 4, 2009 · 60 Comments

Most people labor under the misconception that if we stop greenhouse gas emissions, levels will soon return to their previous values. Global warming will stop, sea level rise will be averted, things will generally return to “normal” in reasonably short order. In fact this may be at the root of the idea that we’re not facing an urgent situation, that “a choice can always be made to quickly reduce emissions and thereby reverse any harm within a few years or decades.” Only then, so the thinking goes, should we make any real sacrifices, because by stopping emissions those greenhouse-gas levels and global warming will promptly reverse.

Alas, it’s not true. Once we increase atmospheric carbon dioxide much of that increase persists for a long time. That’s the point of Solomon et al. (2009), Irreversible climate change due to carbon dioxide emissions (Proceedings of the National Academy of Sciences, 106, 1704, doi:10.1073/pnas.0812721106). The abstract says it quite plainly:

The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the ‘‘dust bowl’’ era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4 –1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6 –1.9 m for peak CO2 concentrations exceeding ~1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.

The reason for the irreversibility is that increases in CO2 alter ocean chemistry, which reduces the ability of the oceans to absorb the extra CO2 on less than millenial time scales. As the authors state:

As has long been known, the removal of carbon dioxide from the atmosphere involves multiple processes including rapid exchange with the land biosphere and the surface layer of the ocean through air–sea exchange and much slower penetration to the ocean interior that is dependent upon the buffering effect of ocean chemistry along with vertical transport (9–12). On the time scale of a millennium addressed here, the CO2 equilibrates largely between the atmosphere and the ocean and, depending on associated increases in acidity and in ocean warming (i.e., an increase in the Revelle or “buffer” factor, see below), typically ~20% of the added tonnes of CO2 remain in the atmosphere while ~80% are mixed into the ocean.

Of the CO2 we’ve already emitted (since pre-industrial times), about half has already been removed from the atmosphere, mostly absorbed into the oceans. About 40% of the increase we’ve caused so far (about 20% of our emissions so far) will persist for 1,000 years — so even if we stop all emissions today, we can expect about 45 ppmv of the 115 ppmv we’ve already caused still to be in the atmosphere in the year 3,000. The authors estimate the millenial-scale equilibrium CO2 levels, depending on the peak CO2 levels brought about by our emissions:


It’s worth noting that only if CO2 level peaks at 460 ppmv or less will the millenial-time scale CO2 level retreat to the 350 ppmv threshold which has been suggested as an upper limit to avoid dangerous interference with the climate system. In fact even at that, CO2 levels will be over 350 ppmv for a very long time, which is probably not a safe place to be.

The also estimate the surface temperature increase over time, depending on how high we raise CO2 levels before we bring emissions to a halt:


They further estimate the possibility of drought in vulnerable areas, again as a function of peak CO2 levels:


It’s disturbing to consider how many highly populated regions are vulnerable to drought, and how much more severe and long-lasting than past droughts the damage will be.

My honest opinion: the scenarios illustrated in Solomon et al. are best-case scenarios. They don’t take into account the possibility of melting permafrost releasing tremendous amounts of addtional CO2 and other greenhouse gases into the atmosphere, or disintegration of methane clathrates, or the impact on ocean life of acidification due CO2, and they deliberately make the most conservative sea-level rise estimates possible, setting only a lower bound on that unpleasant possibility.

Overall, it seems to me that we absolutely must prevent peak CO2 levels from exceeding 450 ppmv to avoid dangerous climate change, and even that may not be enough. At the present rate of increase, we’ll hit 450 around the year 2040.

We don’t have much time.

Categories: Global Warming

60 responses so far ↓

  • David Gould // September 4, 2009 at 2:59 am | Reply

    I honestly do not see how we can avoid exceeding 450 ppm; indeed, 550 ppm looks tricky to avoid. I am pretty sure that we will reduce our emissions to zero over the course of this century, but I think that most of that reduction will occur in the second half of the century, unfortunately.

  • Geoff Beacon // September 4, 2009 at 5:20 am | Reply

    Urgent. Urgent enough?

    I speak to several government ministers each year. Now I can reference this blog to point to weightier views than my own. Thanks.

    Last year I did meet Lord Turner (chair of the UK Climate Change Committee). I have posted the questions he agreed to answer on .

    No answer yet… And I have spoken to him since.

    I will be catchiing other politicians, government officials and scientists in the next few months. Any suggestions for making them listen or opics to address are welcome.

  • cce // September 4, 2009 at 5:43 am | Reply

    I think that for the portion of the public who accept AGW as true (i.e. the rational portion), but are kind of wishy-washy about actually doing anything about it now, this is the most important point to convey to them. They just down’t understand the lifetime of the changes we’ve caused.

    I think for the 350 targets which will require both massive decreases in emissions, plus large agricultural sequestration projects, we need to abandon the idea of “% reductions by X” and think of the problem as two bank accounts. One account represents the total amount of carbon we can emit into the air so as to keep concentrations below the maximum safe, temporary limit. We can only withdraw from this account, and once it reaches zero, then we can’t emit any more. Needless to say, we’re quickly depleting this account.

    The other account represents the amount of carbon we must sequester to get concentrations back down to 350 by a certain deadline. We can only deposit into this account, and it shouldn’t be able to lend to the other. Sequestering that amount of carbon using agricultural methods will be very difficult and it shouldn’t be used to replace or put off emissions cuts.

    That is, I think there should be two carbon markets with two prices and two pathways, one for emissions cuts and one for sequestration. But given the state of national and global negotiations, that’s probably a fantasy.

  • crf // September 4, 2009 at 6:36 am | Reply

    Some people think that, in the future, carbon dioxide will be pulled directly out of the atmosphere on a large scale using machines.

    This idea is taken as an excuse not to make emissions reductions at all, or to back-load them.

  • Gareth // September 4, 2009 at 8:34 am | Reply

    The unfortunate complicating factor (which I discuss here in the context of emissions cut targets) is that if we look at CO2e (ignoring aerosols) we’re already well on the way to 450 ppm (about 435ish, from memory). The message of the Ramanthan & Feng paper I reference is that if we reduce aerosols, there are already enough GHGs around to cause irreversible change. There’s a delicate balance to be struck between cutting emissions and cleaning up aerosols, because the latter are doing us a big favour.

    But that assumes that we’ve a) got the wisdom and the will to act, and b) it’s not too late to avoid major carbon cycle feedbacks. I have doubts on both scores.

  • Glenn Tamblyn // September 4, 2009 at 9:17 am | Reply

    Achieving the scale of reductions needed in the necesary time frame is still achievable.

    However, the pace at which the technologies that replace current energy systems etc in order cut emissions – renewables, nuclear, CCS etc can be rolled means they cannot meet the time frames needed. I don’t think that is technically achievable as a matter of logistics.

    So to meet our necesary emissions reduction goals requires that we institute major planet wide action using those things we can do right now. And these are essentially energy efficiency measures on a scale that goes through the the world economy like a dose of salts. Starting Now.

    Then the introduction of other demand management measures that stop the rise of the emissions curve over the next 2 decades while we wait for the technical and logistical rollout of the alternate technologies

    Essentially, planet wide energy rationing. The introduction of what is in effect a wartime like mobilisation of every country in the world. Perhaps the suspension of economic Business-as usual. Possibly the closing of the worlds stockmarkets for 20 years and actions of similar severity.

    Action like this could still achieve the change we need in time. Anything less and we have missed the boat.

    This is all doable in a technical sense. How totally not doable this is politically, economically, socially I am sure you all understand. The scale of social upheaval required to make sure we are safe is a couple of orders of magnitude beyond where the politics and broad public opinion are at. And I don’t mean the Denialosphere. I mean the level of awareness of most of the general public who ARE convinced of AGW’s reality.

    Oh how we may come to regret those wasted years since Rio 1992.

  • Curious // September 4, 2009 at 3:37 pm | Reply

    I don’t think it is (just) a question of social awareness, but (specially) a question of policymakers’ responsibility. In my country there is much skepticism among the lay public, but the government is well informed, and therefore does (more or less) what he is suposed to do, and when facing some skeptic they just say: you’re wrong. It’s like speed limits or taxes. They might not be very popular, but the government dosen’t care about popularity when something more important is at stake.

    What’s the difference between the EU and the US? Why is the EU able to reduce their emissions without a remarkable economic impact whilst in the US it seems impossible?

  • Curious // September 4, 2009 at 3:44 pm | Reply

    only if CO2 level peaks at 460 ppmv or less will the millenial-time scale CO2 level retreat to the 350 ppmv threshold which has been suggested as an upper limit to avoid dangerous interference with the climate system

    But we have already surpassed that limit! I’ve always heard of 400-450 ppm as a dangerous threshold. Am I missing the meaning of the statement? Or should I check new sources to update my understanding?

    That CO2 threshold refers to “equivalent forcing”, isn’t it? (I know that currently the CO2 forcing equals the net forcing).

    I’ve always wondered how much more we can add to the atmosphere with the known fossil fuel reservoirs. I’ve sometimes heard that we are going to run out of fossil fuels within 40 years. Does anyone know up to what atmospheric CO2 concentration we could reach with the knonw fossil fuel reservoirs?


    • Eric L // September 4, 2009 at 6:17 pm | Reply

      I’ve sometimes heard that we are going to run out of fossil fuels within 40 years.

      You might have heard that about oil, but it’s certainly not true of coal. Peak oil may have already happened, but that doesn’t mean we’re out, it just means we won’t use it at a faster rate than we are using it now, so it will steadily decline, but I’d imagine it would take at least a century to run out.

  • Geoff Beacon // September 4, 2009 at 4:55 pm | Reply

    Should reduction in methane be a prority?

    I learnt from this blog or RealClimate that the concentration of methane in the atmosphere is proportional to steady state annual emmissions within a decade – or not much more. If methane emissions could be halved this would cut radiate forcing substantially.

    Can anyone express this in ppm of CO2 equivalent for me?

  • Curious // September 4, 2009 at 5:55 pm | Reply

    Geoff Beacon,

    Even though the methane molecule is 25 times more powerful than CO2 regarding the greenhouse effect, there is about 200 times less methane in the atmosphere than CO2. That’s why, even though methane has increased 150 % (much more than the 35% of CO2), the radiative impact of this increase has been “only” 0,48 W/m2, three times less than the 1,6 W/m2 of a 35% increase of CO2.

    Besides, CO2 is a long lived greenhous gas that stays in the atmosphere for about 100 years, while methane lasts about 10 years.

    To do the numbers you can use the formulas in table 1 here:

  • John N-G // September 4, 2009 at 6:57 pm | Reply

    The Solomon article is important and sobering, but I strongly object to its characterization of the “dust bowl”. Dry-season multi-year precipitation reductions in the core areas of the 1930s Dust Bowl compared to century-long averages were generally 25%-35%, not the 5%-15% that’s listed in the figure as the “observed range of major drought”. No studies listed in Solomon’s references came to the conclusion she’s quoting about the nature of drought.
    Plus, the Dust Bowl was caused as much by unsustainable farming practices as by drought. Droughts of similar intensity have occurred in the same areas since the 1930s without the associated catastrophe and social upheaval.
    I’m seriously considering writing a paper reminding people about the true nature of the Dust Bowl, in a possibly futile attempt to prevent “450 ppb = Dust Bowl” from being one of the main messages of IPCC 5.

  • Kaj Luukko // September 4, 2009 at 8:46 pm | Reply

    Looks like in the near future we need some technology to remove carbon dioxide from the atmosphere. Power plants using bio-fuel and CCS-technology might be a part of the solution.

  • Geoff Beacon // September 4, 2009 at 9:24 pm | Reply


    “That’s why, even though methane has increased 150 % (much more than the 35% of CO2), the radiative impact of this increase has been “only” 0,48 W/m2, three times less than the 1,6 W/m2 of a 35% increase of CO2.”

    I’ve seen the equations you point too before. I was hoping to avoid the work of applying them.
    But if we cut methane by half what would be the change in CO2e in ppm?

    Your “the methane molecule is 25 times more powerful than CO2 “. Is that GWP over 100 years or something I haven’t got to grips with yet.

  • David B. Benson // September 4, 2009 at 9:24 pm | Reply

    Curious // September 4, 2009 at 3:44 pm — Suggest reading Target atmospheric CO2: Where should humanity aim?:

    Since potential fossil fuels include methyl clathrates, vastly too high.

    Kaj Luukko // September 4, 2009 at 8:46 pm — One proposal is to burn biochar in pure oxygen (with, then elevated temperatures). Turns out most coal burners can be converted to do that.

    The flue gas is then almost pure CO2, suitable for sequestration. The use of under ocean basalt formations is recommended for injecting the CO2 into.

  • Curious // September 4, 2009 at 10:11 pm | Reply

    Geoff Beacon,
    I’m not good with the numbers either, I may try, but I may mess things up. Besides, I was thinking of reducing the concentrations on the atmospehere ( if +150 % has added +0,48 W/m2, then a rule of three would say that half of that increase (+75%) could be something like 0,24 W/m2), but I don’t know if that would be the atmospheric impact of halving our emissions. I just wanted to put across the intuitive idea that CO2 strategies have a greater impact and to point out to a reliable source with the formulas (applicable to atmospheric changes), but I am not qualified to work them out. Sorry.

  • Curious // September 4, 2009 at 10:16 pm | Reply

    David B. Benson,

    Thanks!! :-)

  • george // September 5, 2009 at 12:31 am | Reply

    My honest opinion: the scenarios illustrated in Solomon et al. are best-case scenarios. They don’t take into account the possibility of melting permafrost … or disintegration of methane clathrates, or the impact on ocean life of acidification due CO2,…”

    …and Solomon et al also assume a temperature increase for CO2 doubling of about 2°C which is at the lower end of the probable range given by IPCC in AR4 (“2 to 4.5°C with a best estimate of about 3°C”)

    (for a one-to-one correspondence between the CO2 graphs and the temperature graphs shown above)

  • David B. Benson // September 5, 2009 at 1:22 am | Reply

    “Why a climate crisis is like an epileptic seizure”:
    appears unusually well written.


  • paulm // September 5, 2009 at 4:31 am | Reply

    There is of course one aspect to all this which means were more than likely screwed…

    Ocean Acidification Reveals Unseen Face of CO2 Pollution

    “Are we screwed?” someone asks from the audience.

    At the podium is Dr. Edward Miles of the University of Washington, in one of the most disturbing sequences in the film, shot at a scientific conference. The attendees have dispensed with the niceties of polite academic disocurse. Dr. Miles pauses, and responds.

    “Are we screwed? Ya, to a considerable extent. A world of 500 parts per million is a world of enormous environmental destruction. We ought to recognize that and say it.”

  • Peter Buck // September 6, 2009 at 6:38 pm | Reply

    I’ve heard that production of meat animals and building construction (or maybe it’s construction and operation) each contribute as much greenhouse gases as the entire transportation sector. David Gould (above) talks about “reducing greenhouse gas emission to zero this century”. I can’t imagine how the meat animal and construction sectors could do this. Any discussion appreciated.

  • David B. Benson // September 6, 2009 at 9:36 pm | Reply

    Peter Buck // September 6, 2009 at 6:38 pm — Beef in particular produces great quntities of CO2 and methane. There is ongoing research into animal feeds which will reduce methane laden belches. This might be as simple as feeding sea weed, either alone or as a substantial suppliment.

    Construction? First I’ve heard of it. It is true that the production of Portland cement releases much CO2, but not as much as the transportation sector, I think.

  • JCH // September 6, 2009 at 10:06 pm | Reply

    We could switch to eating grass-fed horses.

  • Glenn Tamblyn // September 6, 2009 at 10:07 pm | Reply

    Peter Buck

    This isn’t that hard.

    The world goes Vegetarian and phases out most meat consumption (and as a commited carnivour I hate saying this)

    In construction one of the worst culprets is Cement making followed by Plaster making. We phase out the use of both by finding low carbon emission alternatives and change building styles to minimise there use. Perhaps no mor high rise buildings.

    And as population levels off mid century and actually starts to decline (before you factor in any population loss actually caused by AGW) demand for building stocks drops off rapidly.

    A good building should last 50 – 100 years so without continuous poulation growth driving it and possibly excess building stocks due to declining population, construction activity would decline by 50% – 80% since it is now only maintenance and replacement of existing stocks

    All this assumes that by centuries end the consequences of AGW, population size, the hydrological crisis, famine and social collapse aren’t so catastrophic that ‘the construction sector’ hasn’t become ‘the shanty town scavanging sector’.

  • David B. Benson // September 6, 2009 at 11:29 pm | Reply

    JCH // September 6, 2009 at 10:06 pm — That is a delicoius sounded alternative!

    I’ve only eaten horse once — steak tartar in a Parisian resturant.

  • JCH // September 7, 2009 at 12:44 am | Reply

    Big taboo. Horse eating would be, from my limited understanding, comparatively GHG neutral. In terms of methane from cows, the vegetarians probably cause just as much, if not more methane to be produced. First, India has a huge population of cattle: and second: rice production makes lots of methane methane. Grass feeding eliminates a great deal of the CO2 production associated with ruminants. Gil and Rowdy could walk them to market.

    And who is going to kill off all the wild ruminants? they’re also producing a large amount of methane.

    But I have my doubts that anybody is going to succeed in convincing Elsie to stop belching methane.

  • Geoff Beacon // September 7, 2009 at 2:13 am | Reply

    One ounce of beef is one days food ration and nothing else to eat?

    The NOBEEF.CO.UK website estimates that the carbon footprint of beef is 37 times its
    own weight. The UK Government has set an anual carbon emissions target of 2 tonnes of
    CO2 per person for 2050. This means that 28gms (1oz) of beef is one day’s carbon ration
    for food.


    Does this sound right?

  • Phil Scadden // September 7, 2009 at 3:07 am | Reply

    Cement is tiny compared to transport, a tenth or less depending on country. There is already work on carbon-negative or at least carbon neutral cement though economic viability may be more of an issue.

  • David Gould // September 7, 2009 at 3:25 am | Reply

    There are also significant land use changes that could be made to reduce greenhouse gas emissions.

    However, the meat industry is a huge problem. The emissions problem is one of the reasons why I became a vegetarian last year. And I think that anyone who is serious about addressing climate change needs to at least consider reducing the amount of meat in their diet (and particularly beef).

  • Geoff Beacon // September 7, 2009 at 4:49 am | Reply

    The embodied carbon in buildings is a very big issue but rarely tackled. BedZED *Beddington Zero Energy Development) was a valuable
    “zero energy” housing experiment. A great part of the value was the embodied carbon calculations done by one of the project
    initiators, Bioregional ( They say

    However, as this report shows, the embodied environmental impacts of BedZED’s construction materials are within the same range
    as standard UK housing. The total embodied CO2 of BedZED is 675kg/m2, whilst typical volume house builders build to 600-800kg/m2.
    Despite the increased quantities of construction materials, the procurement of local, low impact materials has reduced the embodied impact of the scheme by 20-30%.

    Construction Materials Report by Nicole Lazarus, BioRegional Development Group

    A 100 square metre flat in BedZED has embodied carbon of 67.5 tonnes CO2e. The average UK citizen creates 11 tonnes of Carbon
    Dioxide (CO2e) a year (according to UK Government figures). New UK targets aim to cut this by 80%. For the sake of argument
    divide this target equally between categories “consumables”, “building”, “transport” and “government” and treat them as carbon
    rations. This gives the ration for building as 500kg per person per year. For two people living in a 100 square metre flat
    67.5 tonnes CO2e is 33+ years of their building ration. That’s before the flat is heated and all the other necessary buildings
    (shops, offices schools etc) are considered.

  • David Gould // September 7, 2009 at 5:31 am | Reply

    The rice and meat industries produce around 100 million tonnes of methane a year apiece, although rice produces a bit more than meat.

    However, rice provides close to 20 per cent of global calorie intake; meat provides close to 2 per cent.

    The meat industry is much worse per calorie than the rice industry …

  • David Gould // September 7, 2009 at 5:35 am | Reply

    I should note here that those figures have not yet been fully checked out by me; I will endeavour to discover more sources for them.

  • David Gould // September 7, 2009 at 6:04 am | Reply

    This web site has, as best as I can tell, slightly different figures.

    As an approximation of those figures, the world consumes around 7 * 10^15 calories per year.

    Rice makes up about 10 per cent of that; meat makes up less than one per cent.

  • Gareth // September 7, 2009 at 9:24 am | Reply

    There’s an excellent ag methane overview at Nature Reports: Climate Change.

  • Mark // September 7, 2009 at 9:42 am | Reply

    “Your “the methane molecule is 25 times more powerful than CO2 “. Is that GWP over 100 years or something I haven’t got to grips with yet.”

    It’s the strength of it now.

    Why would you think it anything other than that?

    It’s not like working out how much IR is blocked at one instant of time is difficult to do, nor that the residency time makes a difference to that.

    CO2 it makes a difference because although we add 2% a year, it lasts centuries so each 2% is down 0.02% or less each year and we eventually get 200% extra CO2 if we keep our CO2 emission constant.

  • jyyh // September 7, 2009 at 2:13 pm | Reply

    The approximate numbers of livestock output vs. wild ruminant output could be useful in assessing the impact of human-consumed beef. Probably the number and weight of livestock combined is way larger than that of the wild species combined, but by how much? Shouldn’t be too hard to find the numbers. F.e. the cattle of the world weighs about 700 megatons to start with, which is on the same order as the weight of automobiles in the same area. I do eat meat.

  • JCH // September 7, 2009 at 4:55 pm | Reply

    When my great grandfather started ranching his cattle ate grass. Nobody planted it. So their food was carbon neutral. When he took them to market in Kansas City, the cattle walked the entire distance. Again, carbon neutral.

    His ranch was like most land, he had tillable acreage and he had pastures. He raised grains, mostly for human consumption, on his good land, and he fattened cattle on his pastures. There is simply a gigantic amount of land that is good for little else than grass feeding animals.

    He produced an incredible amount of food, and retired a wealthy man.

    It’s not meat that is the problem, it’s how we raise meat. The choice of cattle will probably have to be undone because of methane. Feeding animals grain burns a lot of fossil fuel.

    There are around 110 million cattle in the United States. When I was a kid it was around 135 million, so it’s been going down. India has multiples of that (the vegetarians’ lead weight.) The deer population the United States is going off the chart. I doubt they equal cattle by methane output, but I would bet they are closer than people might think.

    In wild America, I would bet ruminant methane exceeded modern levels. We had huge herds of buffalo and deer, and natural diets possibly produce more methane than grain diets do. Modern deer steal a lot of corn – the little buggers.

  • george // September 7, 2009 at 5:57 pm | Reply

    Mark says

    CO2 it makes a difference because although we add 2% a year,

    We currently increase the atmospheric CO2 concentration each year by about 2ppm (by volume) which is about 0.5% of the total atmospheric CO2 concentration. (about 387ppm)

    We “add” about twice that each year in emissions (or about 1% of the current total atmospheric CO2 concentration by volume), but half of that is quickly absorbed by sinks (eg, oceans) so does not contribute to the yearly increase.

  • Jim Eager // September 7, 2009 at 10:01 pm | Reply

    That half may not contribute to the yearly increase in the atmosphere, but it does contribute to ocean acidification.

  • David Gould // September 7, 2009 at 11:22 pm | Reply

    I would doubt that the world’s wild ruminant population has increased over the last 150 years, although I am sure it has in certain areas. However, we know that the agricultural ruminant population has increased significantly – it is estimated that the world’s cattle population doubled between 1950 and 2000, to its current 1.3 billion.

    And, yes, India is a problem in this regard. A lot of their cows are used for dairy products. So maybe another target should be a reduction in the consumption of dairy products.

  • David B. Benson // September 8, 2009 at 1:38 am | Reply

    Irrigated afforestation of the Sahara and Australian Outback to end global warming
    (The pdf is available to everybody.)

    • Glenn Tamblyn // September 8, 2009 at 8:25 am | Reply


      Massive reaforestation in some of the driest places on earth with some of the poorest soils!

      Using country size amounts of energy expensive desal’ water piped how far?


  • Geoff Beacon // September 8, 2009 at 9:13 am | Reply


    It’s not meat that is the problem, it’s how we
    raise meat. The choice of cattle will probably
    have to be undone because of methane.

    Cattle and sheep are a big problem for AGW, other meats a smaller problem. But have you compared the various carbon footprints with what our daily targets/rations should be? We all need to do these calculations and get government to embed them in our economic system. Try Hansen’s Carbon Fee. See

  • Mark // September 8, 2009 at 10:59 am | Reply

    “We currently increase the atmospheric CO2 concentration each year by about 2ppm (by volume) which is about 0.5% of the total atmospheric CO2 concentration. (about 387ppm)”

    Correct, George. Sorry.

  • Mark // September 8, 2009 at 11:02 am | Reply

    JCR: “There is simply a gigantic amount of land that is good for little else than grass feeding animals.”

    Aye, it’s one problem with people saying “be vegetarian!!!” as the only proper answer.

    But goats and sheep (but goats especially) are a great way of turning marginal land into something you can eat.

    Africa usually doesn’t get enough rain to irrigate HUMAN CONSUMABLE vegetative matter.

    But there’s plenty of scrub grass and bushes grow, they just appear much sparser.

    But a goat will eat and walk over this large area turning inedible grass and leaves into edible meat and milk.

  • Sekerob // September 8, 2009 at 11:53 am | Reply

    Aussies appreciate the ~750 million tonnes of coal they export through coal to maintain their way of life… maybe this afforestation will allow them to take some of that back via the airways. Think the 2007 number stood at 9.4 GT CO2 input with somewhat over 50% absorption.

    At any rate a nice project, but a pipe-dream nevertheless, particular if the AGW friend Lomborg puts his hand on this. He’ll come up with quadrillions of cost out his sleeve to foster the contra fear mongering.

  • David B. Benson // September 8, 2009 at 7:35 pm | Reply

    Glenn Tamblyn // September 8, 2009 at 8:25 am — Water comes from the Mediterrean energized by wind and solar power.

    Sekerob // September 8, 2009 at 11:53 am — Not a pipe-dream in any sense but that lots of pipes will be required.

    In any case, it may well be that this or a similar project can pay its own way by selling biomass derived energy sources.

  • Glenn Tamblyn // September 9, 2009 at 1:32 am | Reply


    Certainly large scale GeoEngineering – have you read the British Royal Society’s recent on GeoEngineering?

    One obvious point. If we embark on major reafforestation, aren’t the unpredictable climate consequences likely to be much lower if we are replacing forests in their original locations? Trying to capture water from locations that were originally able to supply it to the forests as rain sounds simpler and cheaper than mass desal.

    But as an alternative to CCS, it could certainly be started more quickly. However, if the forest is the carbon store, then eventually it will start to release it again. So using this as a start point for a biochar or deep ocean sequestration of the carbon might be viable, with a regular cropping cycle of the forests.

    The down side of this is thet even more than the Coal Companies wet dream of CCS, this becomes a rationalisation for delaying the phase out of fossil fuels. And with the massive capital costs involved, what does that do to world capital markets and the availability of capital for fossil fuel replacement. Could this be Big Carbon’s Get Out Of Jail Freee card?

    The volumes of high salinity water produced by desal on this scale would be staggering. What if the environmental impacts of this turned out to be so bad that the desal had to be suspended and the forest allowed to die? And Coal has kept emitting anyway on the expectation of this working. Could we be worse off?

  • Kevin McKinney // September 9, 2009 at 1:25 pm | Reply

    The reafforestation idea is attractive, but it’s not going to be a silver bullet. I think we need to keep in mind the “mitigation wedges” concept because in the end, that is almost certainly what such initiatives will be–since likelihood of implementation is inversely proportional to scale, in general. (And, as the previous post suggests, this is possibly all to the good.)

    If this concept is true, then one of the things that needs to happen is global coordination and planning of the various “wedges” as they are implemented regionally. Somebody needs to monitor that the sums add up to climatologically useful amounts, and check that initiative A doesn’t economically, technically, or climatically interfere with initiative B.

    Presumably the ongoing “Congress of the Parties” and IPCC processes can handle this need, or evolve into a process that can.

  • Hank Roberts // September 9, 2009 at 5:59 pm | Reply

    > a goat will eat and walk over this large
    > area turning inedible grass and leaves
    > into edible meat and milk.

    And turning an arid ecosystem into mineral soil and windborne dust. Not as bad as what sheep will do, but close enough, unless the program includes very smart paddock management (see Alan Savory’s work, which goes back decades and is well proven, for how to do it right) .

  • David B. Benson // September 9, 2009 at 6:49 pm | Reply

    Glenn Tamblyn // September 9, 2009 at 1:32 am — The high salinity water is either turned over to a mineral extraction company or just sent down a pipe deep into the ocean. Not likely any problem.

    The Sahara was once mostly an open woodland savannah, this just speeds up the thousands of year long cycle to return it to a similar state once again.

    If started properly (slowly) I think it could pay for itself by providing biomass derived energy sources. Maybe a bunch of startup $$ would be required, but not this would directly compete against coal and natural gas. If done properly, it could simply put coal out of business.

  • Alan C // September 10, 2009 at 7:28 am | Reply

    Regarding cattle a few thoughts come to mind. First of all [given my limited knowledge] it seem that if you phase out cattle then you’ll need to replace the pasture with crops. Perhaps I’m wrong here but my impression is that one would require more vegetable matter to get the same nutrition/calories as a serving of meat. Perhaps more land still would be required?
    Also I was under the impression that certain ‘native’ large herbivores such as american Bison were more efficient than introduced cattle.

  • Mark // September 10, 2009 at 10:49 am | Reply

    “And turning an arid ecosystem into mineral soil and windborne dust.”

    funny how the bushmen lived there fore 15000 years without that.

    Rumunants don’t eat grass roots. It’s why grass has taken over: they grow from the base, not the tips.

    Climate change is causing what the people there can get away with, but modern politics means they can’t move.

    So they over-farm.

    Just like ‘merkins did in the 1930’s. They were much more effective because they used tillers to grow plants for human consumption rather than goats to turn scab grass into meat.

  • Mark // September 10, 2009 at 10:57 am | Reply

    Hank, I’m not saying that we must eat meat.

    I’m saying that sometimes using ruminants gives you more food than if you restricted yourself to only vegetation farming.

  • David B. Benson // September 11, 2009 at 10:26 pm | Reply

    Alan C // September 10, 2009 at 7:28 am — The ratio is something like 10:1; animals are an inefficient way to obtain food for humans.

  • Mark // September 14, 2009 at 3:08 pm | Reply

    “The ratio is something like 10:1; animals are an inefficient way to obtain food for humans.”

    But you can’t plant turnips on thin soil.

    You can’t farm steep hills.

    So let the grass grow and let the goats turn it into food.

    It’s about INTELLIGENT use of resources.

    And denying meat resources out of hand isn’t intelligent.

  • Geoff Beacon // September 14, 2009 at 6:22 pm | Reply

    “Methane emissions per kg milk average 77, 38 and 30 l in dairy ewes, goats and cows, respectively. They average 60 and 1160 l per kg cold carcass from indoor fattened and grass lambs, respectively, and 300, 580 and 1040 l/kg for dairy and beef bullocks and 40 month-old beef steers, respectively, including methane production of the dam for meat breeds.”

    Being serious about climate change means taking CO2 out of the atmosphere. Let vegetation grow on the hills and sequester CO2 by biochar.

    But you can farm steep hills with enough labour.

  • Hank Roberts // September 14, 2009 at 6:44 pm | Reply

    > Rumunants don’t eat grass roots.

  • Hank Roberts // September 14, 2009 at 6:46 pm | Reply

    (PS, the second hit from that search is a different IPCC — it’s fa report on sheep problems from the Irish Peatland
    Conservation Council).

  • george // September 24, 2009 at 2:34 pm | Reply

    “Obama on Climate: Is He Even Trying?
    Judging from the UN speech, I am starting to doubt it.” (by Bill McKibben)

    [Response: I think McKibben is way off the mark. If Obama had given the speech McKibben wanted, it would have so undermined his support among the middle class as to sabotage any hopes of progress at all. It's easy for McKibben to whine about what we need; Obama has to pay attention to what we can get.

    Ignoring political and economic reality is foolish. At the moment the political and social "climate" makes total elimination of carbon emissions (which is what we need) downright impossible -- I'll take any reduction I can get (with emphasis on the can get), and you can be damn sure that after Obama get's me that 1st inch, we'll keep taking more and more until we're way past the mile marker, to get what we need in the long run. Insisting on everything right now only gets you branded an extremist -- and gets you nothing in the long run.]

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