I wrote the following to serve as a one-page introduction, laying out some of the key items for consideration and listing some of the most accessible and reputable sources of information about climate change. For more information on specific subjects, see my climate change index.
The key elements of the general climate science and policy consensus are:
- On average, the planet is warming.
- Most of this is because of human emissions of greenhouse gases.
- Continued warming would be harmful, and perhaps very risky when it comes to human welfare and prosperity. Anticipated changes include melting glaciers and polar ice, more extreme precipitation events and heat waves, agricultural impacts, wildfires, heat waves, increased incidence of some infectious diseases, sea level rise, ocean acidification, and increased hurricane intensity.
- By most accounts, the cost of mitigation is less than the cost of adaptation. Some anticipated changes may overwhelm the capacity of human and natural systems to adapt.
While there is a public perception that there is a lot of scientific disagreement about the fundamentals of climate science, this really is not the case. Back in 2004, a survey of peer-reviewed work on climate science demonstrated this. There is also a notable joint statement from the national science academies of the G8, Brazil, China, and India.
To borrow a phrase from William Whewell, there is a ‘consilience of evidence’ when it comes to the science of climate change: multiple, independent lines of evidence converging on a single coherent account. These forms of evidence are both observational (temperature records, ice core samples, etc) and theoretical (thermodynamics, atmospheric physics, etc). Together, these lines of evidence provide a conceptual and scientific backing to the theory of climate change caused by human greenhouse gas emissions that is simply absent for alternative theories, such as that there is no change or that the change is caused by something different.
Readers who are dubious about the validity of mainstream climate science, or unsure of what to think, my page for waverers may be useful.
1) Climatic science and history
There are some good primers available from reputable organizations online. For instance, the United Kingdom’s Met Office has a quick guide.
The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) is the most authoritative review of the scientific work that has been done on climate change. The summary for policy-makers for the synthesis report is available online.
For detailed information on the physical science of climate change, the technical summary of the IPCC’s Working Group I report is a good resource. Unlike the summaries for policy-makers, which are vetted though a quasi-political process, the technical summaries are prepared exclusively by scientists.
For Canadians who want to read one book about climate science and policy, I recommend University of Victoria Professor Andrew Weaver’s book: Keeping Our Cool: Canada in a Warming World.
For those looking for a concise history of the entire development of climatic science, starting in the late 1800s, I very much recommend Spencer Weart’s The Discovery of Global Warming. In addition to the book form, it is available free online.
For a more specific history of what we have learned about climate from ice core samples, see Richard Alley’s The Two Mile Time Machine. For an excellent (though somewhat technical) discussion of the relationships between the carbon cycle and biological organisms, see Oliver Morton’s Eating the Sun.
2) Climate change mitigation
Ultimately, the only way to keep the concentration of greenhouse gases in the atmosphere constant is to reach the point where humanity has zero net emissions. Getting there fundamentally requires two things: the shifting of the energy basis of the global economy to low- and then zero-carbon sources, and the stabilization of the biosphere through actions like ending net deforestation. It is widely accepted that setting a sufficiently high price for greenhouse gas emissions is a vital way to drive mitigation actions.
Three excellent books that evaluate options for moving to a low-carbon economy are:
- George Monbiot’s Heat: How to Stop the Planet from Burning. (In which he considers how the UK could achieve truly dramatic rapid reductions in greenhouse gas emissions)
- Joseph Romm’s Hell and High Water (focused on the United States)
- David Mackay’s Sustainable Energy Without the Hot Air (in which he evaluates renewable and efficiency options from first principles, but in a very accessible way – available free online.)
On the costs of climate change mitigation, the most comprehensive work is probably that which has been done by Nicholas Stern, beginning with the Stern Review. The review’s executive summary is also accessible online. More recently, he has argued that the costs of inaction are even more significant than those projected at that time.
On the political and ethical side of things, the best short summary may be Stephen Gardiner’s article “Ethics and Global Climate Change,” published in Ethics. Volume 114 (2004), p.555-600. One key idea related to international equity and climate change mitigation is contraction and convergence: an arrangement in which the emissions from all states eventually fall to zero, but where the per-capita emissions of developed and developing states also converge over time.
My fantasy climate change policy combines a moratorium on coal and unconventional fossil fuels with a hard cap on emissions.
3) Other major climate change issues
Other areas relevant to climate change policy-making include:
- Abrupt and runaway climate change scenarios
- Adaptation to climate change
- Carbon sinks (physical, such as the oceans, biological, such as the forests, and geological, such as rocks that erode and form carbonates)
- Economics (carbon pricing, risk management, etc)
- Emission pathways (and their international breakdown)
- Equity issues (historical responsibility, climate change and development, etc)
- Global politics and international law
- Planning and design (cities, buildings, etc)
- Science (climatic equilibria, models and projections, etc)
- Sociological and philosophical issues (ethics, communication, political theory, etc)
- Targets (stabilization concentrations, temperature change, etc)
- Technologies (renewable energy, transport, nuclear, efficiency, etc)
I can recommend resources in all of these areas, if someone has a particular interest.
4) Good sources of climate related news
Probably the best scientific climate change blog is RealClimate.
Good responses to climate ‘skeptic’ arguments can be found in the How to Talk to a Climate Skeptic series. I also keep track of my own arguments with climate change deniers.
Climate coverage in mainstream media sources is often inconsistent in quality. The BBC and The Economist often publish good information, but also sometimes include incorrect or misleading information.
5) A few key graphics
This ice core record of carbon dioxide concentrations illustrates one major reason why we should be more concerned about human-induced climate change than about natural variation. Our use of fossil fuels is generating a spike in greenhouse gas concentrations that is set to rise far above anything in the last 650,000 years, at least.
The above shows how observed warming is inconsistent with climate models that do not incorporate human greenhouse gas emissions, but consistent with those that do.
The wheel on the right depicts researchers’ estimation of the range of probability of potential global temperature change over the next 100 years if no policy change is enacted on curbing greenhouse gas emissions. The wheel on the left assumes that aggressive policy is enacted. (Credit: Image courtesy / MIT Joint Program on the Science and Policy of Global Change)
I would be delighted to answer and questions, or suggest further resources in other areas of interest.
Last updated: 10 December 2009
{ 51 comments… read them below or add one }
Can I suggest rewording “not all anticipated changes can be adapted to” to something like “and adaption is not possible for some of the anticipated changes”. Or if you’re really attached to the present wording then maybe add some punctuation (semi colons for the list and then a full stop) because at present it sort of looks as tough you lost part of the sentence.
Re-punctuated, and re-worded. The text ‘some anticipated changes may overwhelm the capacity of human and natural systems to adapt” is very close to or identical to text from the IPCC AR4.
What do you think would be the most intuitive short title to include in the navigation menu at the top of the page?
Or something else entirely?
Wow! what a great resource you have provided for your readers. How about “The One Stop Climate Manual” for a title? I am writing a paper on why the Kyoto protocol is failing fast, and need a good source that is current. I am using your Oxford thesis as a source too.
Nobody ever expected the Kyoto Protocol to singlehandedly deal with the problem of climate change, so it is important to understand it in context.
With many environmental problems, states agree to a convention, such as the United Nations Framework Convention on Climate Change (UNFCCC). These conventions are then expanded upon through protocols, such as the Kyoto Protocol.
The case of ozone depleting substances is illustrative. The original treaty addressing it was the Vienna Convention for the Protection of the Ozone Layer. It was eventually made fairly effective by the ratification and implementation of the Montreal Protocol.
In most cases, the Kyoto Protocol has not succeeded in curbing the growth of greenhouse gas emissions, either in developed nations that adopted hard caps or in developing states that participated through mechanisms like the Clean Development Mechanism. That said, the Kyoto Protocol was just one step on the route towards an effective international regime for climate change mitigation. The aim of the UNFCCC summit in Copenhagen this December is to try to create a successor treaty. While that may or may not happen this year, it does seem more likely than not that there will eventually be another protocol to the UNFCCC, or perhaps a new convention to replace it.
The Kyoto Protocol has, at the very least, given states more experience with some of the key mechanisms that will be involved in dealing with climate change – including carbon pricing and the transfer of technologies to developing states. The worrisome thing is that we don’t have all that much time to get global emissions to level off and begin falling towards zero. Whereas the costs associated with inaction on issues like acid rain or persistent organic pollutants were moderate, those associated with climate change are potentially catastrophic.
In some senses, the Kyoto Protocol has ‘failed’ insofar as it didn’t establish sufficiently effective mechanisms that states genuinely trying to cut their emissions could use. There have been problems with the carbon markets it established, for instance.
At the same time, it is probably truer to say that states failed to live up to the obligations they voluntarily took on through the Kyoto Protocol, with Canada among the worst offenders. If states like Canada had accompanied ratification with a plan for actually reaching its target – and had then applied the level of effort necessary to implement that plan – the outcomes associated with the protocol as a whole would be quite different.
Kyoto is Ineffective
Objection:
The Kyoto treaty, even if fully implemented, would only save us about a tenth of a degree of future temperature rise many decades from now. What a waste of effort! You can see for yourself here at Junk Science’s website.
Answer:
There are three big problems with this claim.
Firstly, this is really a red herring. The purpose of Kyoto is to establish an international mechanism for dealing with global warming by taking the first tentative steps towards a difficult goal. Political and economic mechanisms need to be worked out and agreed on. You may as well time me waking to the side walk where I parked my car () bicycle, and then tell me at this rate I will never get home.
Secondly, Kyoto is a step by step process whose second phase (much less third, fourth etc.) has not even been negotiated yet, so how can anyone claim anything about how effective it is going to be? Junk Science and other sources of this propaganda are starting their dubious calculations from the assumption that Kyoto ends in 2012 when round one is over, this is just Plain Wrong.
Thirdly, the temperature several decades from now is to a large extent already determined by the current energy imbalance due to the extra CO2 already in the atmosphere right now, so short of a complete cessation of emissions today, there is no foreseeable way to avoid the bulk of the warming that is “in the pipeline”. This is mostly the result of the extremely large thermal inertia of the oceans and therefore the climate system as a whole, and it means that our actions today, or our inactions, will have consequences felt several decades hence.
Finally, a rather personal peeve I have with this type of criticism. In general I have a big credibility issue with people who vociferously criticize any attempt at a solution and yet propose nothing in its place. You’d think if they were so sincerely concerned about how ineffective Kyoto will be (as frankly, they should be!) they would be agitating for more action, rather than shrugging their shoulders and saying “I guess we should just sit it out”. It makes me think of some guy standing on the sidewalk watching all the neighbors fight a house fire, saying “you’ll never make it, [you] don’t [have] enough people.”
Shut up and help!
Thank you for this one page primer.
I would suggest introducing “Change” after “Climate” into whatever short title you choose.
Would you like to write this presentation for me? Thanks for the tips. I need to find more info about China as I plan to use Canada and China as examples. I have lots of detail about Canada. How do I site your thesis and your blog?
David MacKay, whose excellent book I reviewed before, has been appointed Chief Scientific Advisor of the Department of Energy and Climate Change in the United Kingdom and given a staff of 50.
I like ‘Climate science and policy-making’ – reasonable short, non-contentious and covers the focus well
Too long for the navigation menu. I would prefer something shorter than ‘climate in one page,’ actually.
This entire post has been copied verbatim (with hotlinked images, to boot) over at World Changing Canada. While that is consistent with my copyright policy, it does seem a touch excessive.
A short explanation of the greenhouse effect might be a good thing to include.
RealClimate has a good ‘start here’ page.
Climate change is on your doorstep
11 November 2009, by Tamera Jones
If you think climate change is something for the next generation, think again. In a detailed study of trends in UK ecosystems, researchers have found that not only has the environment changed, but everything from butterflies and beetles to soil, is responding.
Researchers measured differences in climate, air pollution, soil chemistry, plant abundance and type, and the numbers and spread of butterflies, moths, bats and beetles across 12 sites in the UK between 1993 and 2007. Reported in the journal Biological Conservation, it’s the most detailed study of UK ecosystems to date.
‘Nowhere else in the world has anyone looked at such a large range of different factors and brought them all together,’ says Dr Mike Morecroft of Natural England, who led the study.
The scientists show that temperatures have risen faster than the global average and rainfall has increased over the period 1993 to 2007 at the 12 sites. But the acidity of rain has dropped dramatically, as a direct result of a clampdown on sulphur emissions since the 1970s, leading to less acid soils at some sites.
Fossil fuel CO2 emissions up by 29 percent since 2000
Published: Tuesday, November 17, 2009 – 13:31 in Earth & Climate
The strongest evidence yet that the rise in atmospheric CO2 emissions continues to outstrip the ability of the world’s natural ‘sinks’ to absorb carbon is published this week in the journal Nature Geoscience. An international team of researchers under the umbrella of the Global Carbon Project reports that over the last 50 years the average fraction of global CO2 emissions that remained in the atmosphere each year was around 43 per cent – the rest was absorbed by the Earth’s carbon sinks on land and in the oceans. During this time this fraction has likely increased from 40 per cent to 45 per cent, suggesting a decrease in the efficiency of the natural sinks. The team brings evidence that the sinks are responding to climate change and variability.
The scientists report a 29 per cent increase in global CO2 emissions from fossil fuel between 2000 and 2008 (the latest year for which figures are available), and that in spite of the global economic downturn emissions increased by 2 per cent during 2008. The use of coal as a fuel has now surpassed oil and developing countries now emit more greenhouse gases than developed countries – with a quarter of their growth in emissions accounted for by increased trade with the West.
The Scientific Consensus on Climate Change: How Do We Know WeWe’’re Not Wrong? (PDF)
Naomi Oreskes
History Department & Program in Science Studies
University of California, San Diego
Responses to Questions & Objections on Climate Change
Dr Brett Parris
Chief Economist, World Vision Australia
Research Fellow, Monash University
“The greenhouse effect, by which gases such as carbon dioxide absorb heat, setting up a warming blanket around the world, was first postulated by the French mathematician and physicist Joseph Fourier in 1824. Fourier understood that solar energy heated the Earth, which then reflected that heat back into space in the form of infrared radiation. In effect, the sun’s heat bounced off the Earth’s surface. In the 1850s the Irish physicist John Tyndall figured out a way to actually test and measure the capacity of various gases, including nitrogen, oxygen, water vapour, carbon dioxide, and ozone, to absorb and transmit radiant energy. By 1858 he had effectively proved Fourier’s theory.
Hoggan, James. Climate Cover-Up: The Crusade to Deny Global Warming. (p.17 paperback)
State of the Climate: Much Worse than Predicted
By Richard Littlemore on US
Given the dated nature of the last report of the Intergovernmental Panel on Climate Change (IPCC), a panel of some of the world’s most respected climate scientists have put together an update called The Copenhagen Diagnosis.
The news is worse than predicted on every front.
“So there it is: the solution to global warming is as easy to describe as it is difficult to put into practice. Emissions of the six kinds of air pollutants causing the problem – CO2, methane, black carbon, halocarbons, nitrous oxide, and carbon monoxide, plus VOCs – must all be reduced dramatically. And we must simultaneously increase the rate at which they are removed from the air and reabsorbed by the earth’s oceans and biosphere.”
Gore, Al. Our Choice: A Plan to Solve the Climate Crisis. (p. 49 paperback)
For Kids, Books that Demystify Climate Change
By Katherine Gustafson
Two new books will help kids, and perhaps their adults, understand what is happening and what they can do to help.
Our Choice: How We Can Solve the Climate Crisis (Young Readers Edition), by Al Gore, is a version of an adult book adapted for youngsters. A follow-up to his famous An Inconvenient Truth, this book departs from Gore’s previous one by emphasizing actions we can take and the hope we can hold on to.
We Are the Weather Makers: The History of Climate Change, by Tim Flannery, is aimed at middle schoolers and high school students, and makes an excellent introduction to the topic for young readers. Its pages cover a range of topics, sometimes technical, including the planet’s carbon cycle, fossil fuels, greenhouse gases and sea-level rise, among others.
It’s a scary and confusing world out there, and kids know it. Turning to some experts for a little child-friendly help is one of the best ways to put fears to rest and to talk about how to face those that can’t be put away. Do you know any other good climate change resources for kids?
In his book, What’s the Worst That Could Happen?, Greg Craven has come up with a useful chain of reasoning, based on the paleoclimatic record:
Collectively, this is one way to argue that humanity’s big experiment with boosting the concentration of greenhouse gasses (GHGs) in the atmosphere is dangerous. The records we have on the history of the climate suggest it can be changed quickly and dramatically. As we continue to emit GHGs, we are pushing towards whichever of those tipping points are closest.
You need think about it. Despite the emails, the overwhelming evidence showing global warming is happening hasn’t changed.
“The e-mails do nothing to undermine the very strong scientific consensus . . . that tells us the Earth is warming, that warming is largely a result of human activity,” Jane Lubchenco, who heads the National Oceanic and Atmospheric Administration, told a House committee. She said that the e-mails don’t cover data from NOAA and NASA, whose independent climate records show dramatic warming.
‘the radical prescriptions for climate change, the ones that come from the green pressure groups, the ones of which politicians instinctively think, “Nah, the electorate will never wear that” are the only ones that are actually going to work. … I find that quite hard to take on board myself, but the implication is unavoidable. In the end it’s a simple choice. One way will work, the other won’t.’
-Michael McCarthy
Pembina Institute
Key Resources on Climate Science
The world’s top climate scientists agree that human activities are forcing climate change at an extraordinary rate — with disastrous consequences if we fail to change course.
In July 2009, Prime Minister Stephen Harper signed on to a G8 summit declaration recognizing the broad scientific view that the increase in global average temperature above pre-industrial levels ought not to exceed 2°C.
The question is no longer whether the climate is changing, but how long we have to act before those changes become irreversible. The following resources summarize the most up-to-date and authoritative climate research.
For someone concerned about climate change, what would you suggest they do?
In order of priority:
Oh, and please keep contributing to discussions here.
What about something to combat deforestation?
“The study, carried out by 12 research groups, showed – for the first time – an acceleration in seasonal timings (phenology) at an environment-wide scale.
Previous studies had identified the trend of spring arriving earlier, but had focused on single species or a small grouping, generally plants.
“We have shown that the acceleration is an average pattern across the terrestrial, marine and freshwater environments,” Dr Thackeray told BBC News.
He explained that the data, covering the period between 1976 and 2005, showed the change was “most pronounced” among organisms at the bottom of the food chains.”
For those who prefer video to text: Peter Sinclair’s video on the evidence for man-made global warming.
Climate change human link evidence ‘stronger’
By Pallab Ghosh
Science correspondent, BBC News
A review from the UK Met Office says it is becoming clearer that human activities are causing climate change.
It says the evidence is stronger now than when the Intergovernmental Panel on Climate Change carried out its last assessment in 2007.
The analysis, published in the Wiley Interdisciplinary Reviews Climate Change Journal, has assessed 110 research papers on the subject.
It says the Earth is changing rapidly, probably because of greenhouse gases.
In 2007 the IPCC’s report concluded that there was “unequivocal” evidence that the Earth was warming and it was likely that it was due to burning of fossil fuels.
Since then the evidence that human activities are responsible for a rise in temperatures has increased, according to this new assessment by Dr Peter Stott and colleagues at the UK Met Office.
The Met Office study comes at a time when some have questioned the entire basis of climate science following recent controversies over the handling of research findings by the IPCC and the Climate Research Unit at the University of East Anglia.
Dr Stott denies that the study has been published as part of a fight back by the climate research community.
“We started writing this paper a year ago. I think it’s important to communicate to people what the science is showing and that’s why I’m talking about this paper.”
The study, which looks at research published since the IPCC’s report, has found that changes in Arctic sea ice, atmospheric moisture, saltiness of parts of the Atlantic Ocean and temperature changes in the Antarctic are consistent with human influence on our climate.
“What this study shows is that the evidence has strengthened for human influence on climate and we know that because we’ve looked at evidence across the climate system and what this shows very clearly is a consistent picture of a warming world,” said Dr Stott.
“The most relevant part of that universal what-else is the requirement laid down by thermodynamics that, for a planet at a constant temperature, the amount of energy absorbed as sunlight and the amount emitted back to space in the longer wavelengths of the infra-red must be the same. In the case of the Earth, the amount of sunlight absorbed is 239 watts per square metre. According to the laws of thermodynamics, a simple body emitting energy at that rate should have a temperature of about –18ºC. You do not need a comprehensive set of surface-temperature data to notice that this is not the average temperature at which humanity goes about its business. The discrepancy is due to greenhouse gases in the atmosphere, which absorb and re-emit infra-red radiation, and thus keep the lower atmosphere, and the surface, warm (see the diagram below). The radiation that gets out to the cosmos comes mostly from above the bulk of the greenhouse gases, where the air temperature is indeed around –18ºC.
Adding to those greenhouse gases in the atmosphere makes it harder still for the energy to get out. As a result, the surface and the lower atmosphere warm up. This changes the average temperature, the way energy moves from the planet’s surface to the atmosphere above it and the way that energy flows from equator to poles, thus changing the patterns of the weather.
No one doubts that carbon dioxide is a greenhouse gas, good at absorbing infra-red radiation. It is also well established that human activity is putting more of it into the atmosphere than natural processes can currently remove. Measurements made since the 1950s show the level of carbon dioxide rising year on year, from 316 parts per million (ppm) in 1959 to 387ppm in 2009. Less direct records show that the rise began about 1750, and that the level was stable at around 280ppm for about 10,000 years before that. This fits with human history: in the middle of the 18th century people started to burn fossil fuels in order to power industrial machinery. Analysis of carbon isotopes, among other things, shows that the carbon dioxide from industry accounts for most of the build-up in the atmosphere.”
“This is an article on climate economics, not climate science. But before we get to the economics, it’s worth establishing three things about the state of the scientific debate.
The first is that the planet is indeed warming. Weather fluctuates, and as a consequence it’s easy enough to point to an unusually warm year in the recent past, note that it’s cooler now and claim, “See, the planet is getting cooler, not warmer!” But if you look at the evidence the right way — taking averages over periods long enough to smooth out the fluctuations — the upward trend is unmistakable: each successive decade since the 1970s has been warmer than the one before.
Second, climate models predicted this well in advance, even getting the magnitude of the temperature rise roughly right. While it’s relatively easy to cook up an analysis that matches known data, it is much harder to create a model that accurately forecasts the future. So the fact that climate modelers more than 20 years ago successfully predicted the subsequent global warming gives them enormous credibility.
…
And this brings me to my third point: models based on this research indicate that if we continue adding greenhouse gases to the atmosphere as we have, we will eventually face drastic changes in the climate. Let’s be clear. We’re not talking about a few more hot days in the summer and a bit less snow in the winter; we’re talking about massively disruptive events, like the transformation of the Southwestern United States into a permanent dust bowl over the next few decades.”
“Scientific conclusions derive from an understanding of basic laws supported by laboratory experiments, observations of nature, and mathematical and computer modeling. Like all human beings, scientists make mistakes, but the scientific process is designed to find and correct them. This process is inherently adversarial—scientists build reputations and gain recognition not only for supporting conventional wisdom, but even more so for demonstrating that the scientific consensus is wrong and that there is a better explanation. That’s what Galileo, Pasteur, Darwin, and Einstein did. But when some conclusions have been thoroughly and deeply tested, questioned, and examined, they gain the status of “well-established theories” and are often spoken of as “facts.”
For instance, there is compelling scientific evidence that our planet is about 4.5 billion years old (the theory of the origin of Earth), that our universe was born from a single event about 14 billion years ago (the Big Bang theory), and that today’s organisms evolved from ones living in the past (the theory of evolution). Even as these are overwhelmingly accepted by the scientific community, fame still awaits anyone who could show these theories to be wrong. Climate change now falls into this category: There is compelling, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystems on which we depend.
Many recent assaults on climate science and, more disturbingly, on climate scientists by climate change deniers are typically driven by special interests or dogma, not by an honest effort to provide an alternative theory that credibly satisfies the evidence. The Intergovernmental Panel on Climate Change (IPCC) and other scientific assessments of climate change, which involve thousands of scientists producing massive and comprehensive reports, have, quite expectedly and normally, made some mistakes. When errors are pointed out, they are corrected. But there is nothing remotely identified in the recent events that changes the fundamental conclusions about climate change:
(i) The planet is warming due to increased concentrations of heat-trapping gases in our atmosphere. A snowy winter in Washington does not alter this fact.
(ii) Most of the increase in the concentration of these gases over the last century is due to human activities, especially the burning of fossil fuels and deforestation.
(iii) Natural causes always play a role in changing Earth’s climate, but are now being overwhelmed by human-induced changes.
(iv) Warming the planet will cause many other climatic patterns to change at speeds unprecedented in modern times, including increasing rates of sea-level rise and alterations in the hydrologic cycle. Rising concentrations of carbon dioxide are making the oceans more acidic.
(v) The combination of these complex climate changes threatens coastal communities and cities, our food and water supplies, marine and freshwater ecosystems, forests, high mountain environments, and far more.
Much more can be, and has been, said by the world’s scientific societies, national academies, and individuals, but these conclusions should be enough to indicate why scientists are concerned about what future generations will face from business-as-usual practices. We urge our policy-makers and the public to move forward immediately to address the causes of climate change, including the un restrained burning of fossil fuels.”
On attribution
How do we know what caused climate to change – or even if anything did?
This is a central question with respect to recent temperature trends, but of course it is much more general and applies to a whole range of climate changes over all time scales. Judging from comments we receive here and discussions elsewhere on the web, there is a fair amount of confusion about how this process works and what can (and cannot) be said with confidence. For instance, many people appear to (incorrectly) think that attribution is just based on a naive correlation of the global mean temperature, or that it is impossible to do unless a change is ‘unprecedented’ or that the answers are based on our lack of imagination about other causes.
…
So how might this work in practice? Take the impact of the Pinatubo eruption in 1991. Examination of the temperature record over this period shows a slight cooling, peaking in 1992-1993, but these temperatures were certainly not ‘unprecedented’, nor did they exceed the bounds of observed variability, yet it is well accepted that the cooling was attributable to the eruption. Why? First off, there was a well-observed change in the atmospheric composition (a layer of sulphate aerosols in the lower stratosphere). Models ranging from 1-dimensional radiative transfer models to full GCMs all suggest that these aerosols were sufficient to alter the planetary energy balance and cause global cooling in the annual mean surface temperatures. They also suggest that there would be complex spatial patterns of response – local warming in the lower stratosphere, increases in reflected solar radiation, decreases in outgoing longwave radiation, dynamical changes in the northern hemisphere winter circulation, decreases in tropical precipitation etc. These changes were observed in the real world too, and with very similar magnitudes to those predicted. Indeed many of these changes were predicted by GCMs before they were observed.
I’ll leave it as an exercise for the reader to apply the same reasoning to the changes related to increasing greenhouse gases, but for those interested the relevant chapter in the IPCC report is well worth reading, as are a couple of recent papers by Santer and colleagues.
“Every piece of valid evidence — long-term temperature averages that smooth out year-to-year fluctuations, Arctic sea ice volume, melting of glaciers, the ratio of record highs to record lows — points to a continuing, and quite possibly accelerating, rise in global temperatures.
Nor is this evidence tainted by scientific misbehavior. You’ve probably heard about the accusations leveled against climate researchers — allegations of fabricated data, the supposedly damning e-mail messages of “Climategate,” and so on. What you may not have heard, because it has received much less publicity, is that every one of these supposed scandals was eventually unmasked as a fraud concocted by opponents of climate action, then bought into by many in the news media.”
Met Office report: global warming evidence is ‘unmistakable’
A new climate change report from the Met Office and its US equivalent has provided the “greatest evidence we have ever had” that the world is warming.
By Louise Gray, Environment Correspondent
Published: 6:00PM BST 28 Jul 2010
The report brings together the latest temperature readings from the top of the atmosphere to the bottom of the ocean
Usually scientists rely on the temperature over land, taken from weather stations around the world for the last 150 years, to show global warming.
But climate change sceptics questioned the evidence, especially in the wake of recent scandals like “climategate”.
Now for the first time, a report has brought together all the different ways of measuring changes in the climate. The ten indicators of climate change include measurements of sea level rise taken from ships, the temperature of the upper atmosphere taken from weather balloons and field surveys of melting glaciers.
New technology also means it is possible to measure the temperature of the oceans, which absorb 90 per cent of the world’s heat.
The State of the Climate report shows “unequivocally that the world is warming and has been for more than three decades”.
And despite the cold winter in Europe and north east America, this year is set to be the hottest on record.
“Overall, Broecker’s paper (together with that of Sawyer) shows that valid predictions of global warming were published in the 1970s in the top journals Science and Nature, and warming has been proceeding almost exactly as predicted for at least 35 years now. Some important aspects were not understood back then, like the role of greenhouse gases other than CO2, of aerosol particles and of ocean heat storage. That the predictions were almost spot-on involved an element of luck, since the neglected processes do not all affect the result in the same direction but partly cancel. Nevertheless, the basic fact that rising CO2 would cause a “pronounced global warming”, as Broecker put it, was well understood in the 1970s. In a 1979 TV interview, Steve Schneider rightly described this as a consensus amongst experts, with controversy remaining about the exact magnitude and effects.”
This is also a good point:
The key elements of climate science have certainly been known for a long time. Back in 1979, the JASON group reached the same basic conclusions as the IPCC:
Under the chairmanship of Jule Charney, a National Academy of Sciences study produced a comparable estimate for climate sensitivity. See: National Academy of Sciences, Climate Research Board (1979). Carbon Dioxide and Climate: A Scientific Assessment (Jule Charney, Chair). Washington, DC: National Academy of Sciences.
“Lately science has shown us that contemporary industrial civilization is not sustainable. Maintaining our standard of living will require finding new ways to produce our energy and less ecologically damaging ways to produce our food. Science has shown us that Rachel Carson was not wrong.
This is the crux of the issue, the crux of our story. For the shift in the American environmental movement from aesthetic environmentalism to regulatory environmentalism wasn’t just a change in political strategy. It was the manifestation of a crucial realization: that unrestricted commercial activity was doing damage – real, lasting, pervasive damage. It was the realization that pollution was global, not just local, and that the solution to pollution was not dilution. This shift began with the understanding that DDT remained in the environment long after its purpose was served. And it grew as acid rain and the ozone hole demonstrated that pollution traveled hundreds or even thousands of kilometres from its source, doing damage to people who did not benefit from the economic activity that produced it. It reached a crescendo when global warming showed that even the most seemingly innocuous by-product of industrial civilization – CO2, the stuff of which plants depend – could produce a very different planet.
To acknowledge this was to acknowledge the soft underbelly of free market capitalism: that free enterprise can bring real costs – profound costs – that the free market does not reflect. Economists have a term for these costs – less reassuring than Friedman’s “neighbourhood effects.” They are “negative externalities”: negative because they aren’t beneficial and external because they fall outside the market system. Those who find this hard to accept attack the messenger, which is science.
We all expect to pay for the things we buy – to pay a fair cost for goods and services from which we expect to reap benefits – but external costs are unhinged from benefits, often imposed on people who did not choose the good or service, and did not benefit from their use. They are imposed on people who did not benefit from the economic activity that produced them. DDT imposed enormous costs through the destruction of ecosystems; acid rain, secondhand smoke, the ozone hole, and global warming did the same. This is the common thread that ties these diverse issues together: they were all market failures. They are instances where serious damage was done and the free market seemed unable to account for it, much less prevent it. Government intervention was required. This is why free market ideologues and old Cold Warriors joined together to fight them. Accepting that by-products of industrial civilization were irreparably damaging the global environment was to accept the reality of market failure. It was to acknowledge the limits of free market capitalism.”
Oreskes, Naomi and Erik Conway. Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming. p.237-8 (hardcover)
Prof. Richard Muller of Berkeley, a physicist who has gotten into the climate skeptic game, has been leading the Berkeley Earth Surface Temperature project, an effort partially financed by none other than the Koch foundation. And climate deniers — who claim that researchers at NASA and other groups analyzing climate trends have massaged and distorted the data — had been hoping that the Berkeley project would conclude that global warming is a myth.
Instead, however, Professor Muller reported that his group’s preliminary results find a global warming trend “very similar to that reported by the prior groups.”
The deniers’ response was both predictable and revealing; more on that shortly. But first, let’s talk a bit more about that list of witnesses, which raised the same question I and others have had about a number of committee hearings held since the G.O.P. retook control of the House — namely, where do they find these people?
We haven’t gone nuts — but the “conversation of democracy” has become so deeply dysfunctional that our ability to make intelligent collective decisions has been seriously impaired. Throughout American history, we relied on the vibrancy of our public square — and the quality of our democratic discourse — to make better decisions than most nations in the history of the world. But we are now routinely making really bad decisions that completely ignore the best available evidence of what is true and what is false. When the distinction between truth and falsehood is systematically attacked without shame or consequence — when a great nation makes crucially important decisions on the basis of completely false information that is no longer adequately filtered through the fact-checking function of a healthy and honest public discussion — the public interest is severely damaged.
That is exactly what is happening with U.S. decisions regarding the climate crisis. The best available evidence demonstrates beyond any reasonable doubt that the reckless spewing of global-warming pollution in obscene quantities into the atmospheric commons is having exactly the consequences long predicted by scientists who have analyzed the known facts according to the laws of physics.
Schmidt,G.A., Ruedy,R.A., Miller, R.L. and Lacis,A.A. 2010. Attribution of the present day total greenhouse effect. JGR 115, D20106, doi:10.1029/2010JD014287, 2010; Lacis,A.A., Schmidt,G.A., Rind,D. and Ruedy, R.A. 2010. Atmospheric CO2: Principal control knob governing Earth’s temperature. Science 330:356-359.
Two recent studies confirm that while only 25 percent of the Earth’s planetary greenhouse effect is caused by the presence of long lived greenhouse gases (particularly CO2), the natural greenhouse effect would collapse without these gases. Furthermore, CO2 concentrations are the primary control for the magnitude of this effect.
Public discussions about the natural greenhouse effect and climate sensitivity to rising CO2 concentrations often indicate a misunderstanding of the roles of long lived greenhouse gases (LLGHGs) relative to those of water vapour and cloud feedbacks within the climate system. Two new studies undertaken by scientists at the NASA Goddard Institute for Space Studies have provided some updated estimates for these roles and reinforce the central role of LLGHGs in the greenhouse effect. In one of these, a team of scientists led by Gavin Schmidt undertake a review of related scientific literature and use the radiation component of their GISS global climate model to examine the role of each of the key components of the greenhouse effect for current and 2xCO2 conditions. They find that for current conditions, water vapour represents 50% of the effect, clouds 25% and CO2 20%. The remaining five percent is due to the minor roles played by other radiation absorbers. While the total effect increases significantly under doubled CO2 conditions, the ratios essentially remain the same. The second study, led by Andrew Lacis, emphasizes the importance of the initial radiative forcing caused by CO2 and the other minor LLGHGs in sustaining the natural greenhouse effect and in causing changes in its magnitude. They show that, without this initial forcing, the greenhouse effect would collapse, leaving the Earth a frozen planet. Increases in CO2 are also the primary driver of enhanced greenhouse effects and the resulting rise in surface temperatures. That is, while the roles of water vapour and cloud effects are very important in the net greenhouse effect, they function as feedbacks rather than primary drivers of change.
Summary courtesy of Environment Canada
Davis, S.J., K. Caldeira, and H.D. Matthews. 2010. Future CO2 emissions and climate change from existing energy infrastructure. Science 10 September, 2010 Vol 328 pp 1330-1333.
The long lifetime of existing transportation and energy infrastructure means that continued emissions of CO2 from these sources are likely for a number of decades. This ‘infrastructural inertia’ alone is projected to produce a warming commitment of 1.3°C above the pre-industrial era. This result emphasizes that extraordinary measures will be required to limit emissions from new energy and transportation sources if global temperature is to be stabilized below 2°C.
Climate modeling has demonstrated that even if atmospheric composition was fixed at current levels, continued warming of the climate would occur due to inertia in the climate system. This form of climate change commitment has become widely recognized. Davis et al. focus attention on inertia in human systems, by asking ‘what CO2 levels and global mean temperature would be attained if no additional CO2-emitting devices (e.g., power plants, motor vehicles) were built but all the existing CO2-emitting devices were allowed to live out their normal lifetimes?”. Barring widespread retrofitting or early decommissioning of existing infrastructure, these committed emissions represent ‘infrastructural inertia’. The authors developed scenarios of global CO2 emissions from existing infrastructure directly emitting CO2 to the atmosphere for the period 2010 to 2060 (with emissions approaching zero at the end of this time period) and used the University of Victoria Earth System Climate Model to project the resulting changes in atmospheric CO2 and global mean temperature. Projections with low, mid and high emissions scenarios led to projected global average warming of 1.3°C (1.1° to 1.4°C) above the pre-industrial era. Since new sources of CO2 are bound to be built in the future in order to satisfy growing demands for energy and transportation, the committed warming from existing infrastructure makes clear that satisfying these demands and achieving the 2°C target of the Copenhagen Accord will be an enormous challenge.
Summary courtesy of Environment Canada
Earth’s Climate History: Implications for Tomorrow
By James E. Hansen and Makiko Sato — July 2011
The past is the key to the future. Contrary to popular belief, climate models are not the principal basis for assessing human-made climate effects. Our most precise knowledge comes from Earth’s paleoclimate, its ancient climate, and how it responded to past changes of climate forcings, including atmospheric composition. Our second essential source of information is provided by global observations today, especially satellite observations. which reveal how the climate system is responding to rapid human-made changes of atmospheric composition, especially atmospheric carbon dioxide (CO2). Models help us interpret past and present climate changes, and, in so far as they succeed in simulating past changes, they provide a tool to help evaluate the impacts of alternative policies that affect climate.
Paleoclimate data yield our best assessment of climate sensitivity, which is the eventual global temperature change in response to a specified climate forcing. A climate forcing is an imposed change of Earth’s energy balance, as may be caused, for example, by a change of the sun’s brightness or a human-made change of atmospheric CO2. For convenience scientists often consider a standard forcing, doubled atmospheric CO2, because that is a level of forcing that humans will impose this century if fossil fuel use continues unabated.
We show from paleoclimate data that the eventual global warming due to doubled CO2 will be about 3°C (5.4°F) when only so-called fast feedbacks have responded to the forcing. Fast feedbacks are changes of quantities such as atmospheric water vapor and clouds, which change as climate changes, thus amplifying or diminishing climate change. Fast feedbacks come into play as global temperature changes, so their full effect is delayed several centuries by the thermal inertia of the ocean, which slows full climate response. However, about half of the fast-feedback climate response is expected to occur within a few decades. Climate response time is one of the important ‘details’ that climate models help to elucidate.
A three-year-long pole-to-pole series survey to collect data on greenhouse gas will end on Friday, say U.S. scientists.
The survey, is known as HIPPO, comprised several pole-to-pole research flights that successfully collected atmospheric gases in three years and generated the first-ever detailed mapping of gases and particles that affect Earth’s climate, they say.
Climate change
The heat is on
A new analysis of the temperature record leaves little room for the doubters. The world is warming
FOR those who question whether global warming is really happening, it is necessary to believe that the instrumental temperature record is wrong. That is a bit easier than you might think.
There are three compilations of mean global temperatures, each one based on readings from thousands of thermometers, kept in weather stations and aboard ships, going back over 150 years. Two are American, provided by NASA and the National Oceanic and Atmospheric Administration (NOAA), one is a collaboration between Britain’s Met Office and the University of East Anglia’s Climate Research Unit (known as Hadley CRU). And all suggest a similar pattern of warming: amounting to about 0.9°C over land in the past half century.
To most scientists, that is consistent with the manifold other indicators of warming—rising sea-levels, melting glaciers, warmer ocean depths and so forth—and convincing. Yet the consistency among the three compilations masks large uncertainties in the raw data on which they are based. Hence the doubts, husbanded by many eager sceptics, about their accuracy. A new study, however, provides further evidence that the numbers are probably about right.
Here’s all you ever really need to know about CO2 emissions and climate:
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