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Filed under: — eric @ 24 November 2009

Nov. 24th, 2009 Copenhagen Diagnosis

The ‘Copenhagen Diagnosis‘, a report by 26 scientists from around the world was released today. The report is intended as an update to the IPCC 2007 Working Group 1 report. Like the IPCC report, everything in the Copenhagen Diagnosis is from the peer-reviewed literature, so there is nothing really new. But the report summarizes and highlights those studies, published since the (2006) close-off date for the IPCC report, that the authors deemed most relevant to the negotiations in Copenhagen (COP15) next month. This report was written for policy-makers, stakeholders, the media and the broader public, and has been sent to each and every one of the COP15 negotiating teams throughout the world.

Among the points summarized in the report are that:

The ice sheets are both losing mass (and hence contributing to sea level rise). This was not certain at the time of the IPCC report.

Arctic sea ice has declined faster than projected by IPCC.

Greenhouse gas concentrations have continued to track the upper bounds of IPCC projections.

Observed global temperature changes remain entirely in accord with IPCC projections, i.e. an anthropogenic warming trend of about 0.2 ºC per decade with superimposed short-term natural variability.

Sea level has risen more than 5 centimeters over the past 15 years, about 80% higher than IPCC projections from 2001.

Perhaps most importantly, the report articulates a much clearer picture of what has to happen if the world wants to keep future warming within the reasonable threshold (2°C) that the European Union and the G8 nations have already agreed to in principle.

The full report is available at Three of us at RealClimate are co-authors so we can’t offer an independent review of the report here. We welcome discussion in the comments section though. But read the report first before commenting, please.

146 Responses to “Copenhagen”

  1. 51
    Tony O'Brien says:

    Can’t you just see the headlines in forty years:”Why didn’t they tell us?”

    This is still a fairly conservative projection.

  2. 52
    David Horton says:

    “Longer growing season, more arable land” – why don’t you check out the situation in Australia, once one of the “breadbaskets” of the world. Higher temps and lower rainfall are causing massive crop losses. The soil dries out, top soil blows away, heat stress kills plants directly, pest/weed species increase, and the rivers are dry or drying, so irrigation is no longer able to compensate. Bushfires in forests and grasslands and even crops add to the problems. Not some alarmist prediction of the distant future – now. So poor is the prognosis for the rich agricultural lands of southern Australia that even the former conservative government started an inquiry into whether the agriculture of the bottom half of the continent could be moved to the northern tropical half – it can’t because of soil, heat, rainfall patterns, pests. So there are no pluses for Australia in the prognosis. How do you think other grain producing countries are going to make out?

  3. 53
    Bernie says:

    Viento’s appropriate question was why wasn’t Siddal et al (2009) cited?

    [Response: The review doesn’t cite every possible paper published. It is a review of what we believe to be an accurate reflection of the most up-to-date science. Sidall is not up to date, because there appears to be a clear error in it, which correcting puts back in the same values as found by Rahmstorf. And as far as I am aware, the authors agree with Rahmstorf’s assessment of the mistake he found, and articulated very clearly in the link I gave.–eric]

  4. 54
    PHG says:

    Excellent summary.

    Personally, I thought the pictures were great as well.

    Lots of work to do over the next decade or so.

  5. 55
    AlCrawford says:

    Surging greenhouse gas emissions: Global carbon dioxide emissions from fossil fuels in 2008 were nearly 40% higher than
    those in 1990. Even if global emission rates are stabilized at present-day levels, just 20 more years of emissions would give a
    25% probability that warming exceeds 2°C, even with zero emissions after 2030. Every year of delayed action increases the
    chances of exceeding 2°C warming.”

    That statement, from the Executive Summary of the report, is alarming. However, I do not question its accuracy so I would not call it “alarmist”. The primary reason I find it alarming is that I see little hope of stabilizing global emission rates anytime soon. The politics in the United States do not lend themselves to doing that. And China and India will likely continue to increase their emission rates. And I have no hope of a reduction of the world emissions to anything near to zero after 2030. For me personally it will make little difference. At my current age the life-expectancy tables indicate I should not live until 2030. But for my grandchildren and great-grandchildren and the generations that (may) come after them that is another story.

    The Copenhagen Diagnosis points out to a number of places where the latest IPCC report missed the mark in its predictions. And in every case things are proving to be worse, even much worse, than the IPCC reports. It makes me wonder at times just how bad it really is!

  6. 56
    blagan says:

    RE: # 13 “Why not?”

    Analysing trends in noisy climate data is a complex exercise as you note. Short term features are not of representative long term trends and may merely represent internal variability of a complex (climate) system.
    Ref: Wunsch,C. 1999 BAMS 80(2):245-255
    Even as the climate models are far from perfect and under intense scrutiny, the statistics over a long enough period (few decades) capturing salient features of climate variability are expected to agree to some extend with the
    current climate state but not individual episodes.

  7. 57
    David B. Benson says:

    Unfortunately my copy of Acroread states that there are errors in both the high and low res versions of the full report pdfs. So I can’t read the report. :-(

  8. 58
    calyptorhynchus says:

    This is a bit off topic, but I just wanted to say that I have been reading denialist postings on this website and on denialist websites themselves (depressing stuff), and I can’t actually see what it is denialists are frightened of.

    The worse that the alleged international conspiracy is going to force us to do is move over to cleaner methods of power generation. manufacturing and transport. What’s the problem with this?

  9. 59

    31 Response by Eric,

    Thanks for your response. But actually I am the top physicist in California; and maybe in the USA and the developed world. (That is a joke — but sort of not.)

    I have established that there is no person in an influential position in California that understands that electric cars cause CO2 in an amount that is greater than hybrid cars of otherwise the same quality. Thus, only one of the two energy goals, cutting oil dependency and reducing CO2 is being dealt with by the shift to plug-in electric cars that is being strongly promoted by our Air Resources Board, PUC, and Energy Commission as well as the office of the Governor. EPA and the DOE seem to be similarly without expertise, judging from federal stimulus to electric cars while ignoring the only emerging car of merit for reducing CO2, that being the Aptera.

    We can not even get straight the idea that energy conversion from heat to electricity is not done at the same efficiency as conversion from electricity to heat. California has repealed the Second Law of Thermodynamics and it appears that the USA is about to follow suit.

  10. 60
    Vinny Burgoo says:

    If I want to prop up my arguments by referring to the scientific consensus, can I say that this intended update represents the current consensus or should I stick with the original AR4 WG1 report?

    [Response: It’s important to recognize that although we believe we have accurately reflected the current state of knowledge, this document did not go through the same level or reivew as IPCC did.–eric]

  11. 61
    Don Shor says:

    I agree with Nicholas Nierenberg regarding hyperbole.

    Re: sea level.
    There is nothing I can find in the body of the IPCC report that shows a 2 meter rise by 2100 (see the table on p. 40). Yet the conclusion states “an upper limit of 2 meters.” Why?
    There are three studies cited on the table. Quoting from one of them:
    “…this relationship results in a projected sea-level rise in 2100 of 0.5 to 1.4 meters above the 1990 level.”
    Rahmstorf 2007

    The current rate of increase is about 30 cm (Wikipedia; sorry!) per century. IPCC 2001 projected a range of 11 – 77 cm increase. New evidence projects a range of 50 – 140 cm. (For Americans like myself, that means that the rate of sea level rise is expected to increase from the current 1.2” per decade to somewhere between 2” – 5.5” per decade.) Is there some evidence that makes the higher range more probable? If not, then why put the highest number, and indeed one not even presented in the body of the work, in the Summary?

    Maybe I’m missing something here.

  12. 62
    semiguy says:

    Communism! Man-on-dog sex! Zombie liberals eating conservative babies! Forced teabagging!

    Something like that, anyways. Hard to say in a straightforward grammatical (much less logical) construct as far as the ‘Palin is a goddess’ crowd is concerned.

    A handful of the smarter ones seem opposed to ‘cap and trade’ policies, and see these as being inextricably linked to global warming science, for reasons that aren’t immediately clear. I actually tend to agree that cap and trade is bad policy, but don’t see it as the only (and certainly not the preferred) option.

    Oh, you were asking about oil company profits? Ignore the man behind the curtain…

  13. 63
    Ike Solem says:

    Chip, you say.

    “–in fact, I am comparing observed trends with the full range of trends derivable from all climate models for all periods of a particular length (5 to 15 years) projected during the first 20 years of the 21st century under the SRES A1B scenario (one which according to the Copenhagen Diagnosis underestimates the emissions which have taken place—so my test should be on the conservative side). It would be difficult to do a more thorough test that the one I am performing.”

    I think “a more useless and biased test” would be the accurate phrase there. Are you trying to promote the theme that there hasn’t been any warming in the past 11 years? Via some bogus statistical hat tricks?

    For example, let’s look at climate model efforts to predict El Ninos – not very useful, right? How about for the weather forecast a year from now? Also not very useful. What about Arctic sea ice loss, and glacial shrinkage?

    Very useful for that, right?

    Your approach is rather like that of the health inspector who tests everyone at a company who works with a toxic material, rather than just the workers who are exposed, and then reports an ‘average level.’ It’s statistical gibberish – and claims that this is ‘just an accident’ are not very believable. It’s a deliberate effort to distort data – and that’s the reason your kind of garbage gets savaged in peer review and rejected for publication.

    For example, Chip, let’s take this post of yours on Romm’s Climate Progress web site:

    Comment 13. Chip Knappenberger says:
    March 30, 2009 at 5:15pm

    Mr. Romm, I am not sure how you justify this statement:

    “At the same time that CO2 emissions are soaring, CO2 sinks are saturating.”

    This has been noted by many different researchers, the most recent being:

    Oceans’ Uptake of Human-Made Carbon May Be Slowing

    ScienceDaily (Nov. 19, 2009) — The oceans play a key role in regulating climate, absorbing more than a quarter of the carbon dioxide that humans put into the air. Now, the first year-by-year accounting of this mechanism during the industrial era suggests the oceans are struggling to keep up with rising emissions — a finding with potentially wide implications for future climate. The study appears in the November 19 issue of the journal Nature.

    Regardless, you published this:

    So are you now going to retract that claim in the light of new information, or is it time to keep the PR guns blazing for Copenhagen? You also fail to note that Knorr’s paper rests entirely on his opinion of the land use changes – in spite of the fact that more and more ecosystems are trending towards becoming net carbon emitters as standing biomass is reduced:

    “…tree deaths in the West’s old-growth forests have more than doubled in recent decades, likely from regional warming and related drought conditions.”

    “…The 30-year study, published in Science, provides the first solid evidence that drought causes massive carbon loss in tropical forests, mainly through killing trees.

    Your blog doesn’t mention this, does it? Why not? Try this for better coverage:

    Likewise, your more recent post on the 2:1 ratio of record highs to record lows is another bad joke:

    Meehl et al. [in press?] find that the reason more daily maximum temperature records are being set than daily minimum temperatures records is because there are fewer than expected daily lows records being set, not because there are more daily high records than expected.

    Ummm… what climate model did they get the “correct” projected number of daily lows from? Or was that what the Farmer’s Almanac predicts, based on past records? Why do you think the researchers focused on the ratio? Do you even understand why the ratio of highs and lows is expected to be constant if the planet is in steady-state equilibrium?

    All in all, you are not being very convincing – it just looks like more efforts to stall binding emissions targets on behalf of the fossil fuel lobby.

  14. 64
    Jere Krischel says:

    How would you adjust this paper if you had to throw out any reference to Mann, Briffa, Jones, or any papers co-authored by them?

    [Response: I assume you mean “How much would you adjust the report?” Answer: it would change nothing in the report. Zero, zilch, nada.–eric]

  15. 65
    SecularAnimist says:

    calyptorhynchus wrote: “The worse that the alleged international conspiracy is going to force us to do is move over to cleaner methods of power generation. manufacturing and transport. What’s the problem with this?”

    The obvious problem with that is that ExxonMobil alone rakes in some $40 Billion in profit every year. When you add up the profits of the other fossil fuel corporations, both oil and coal, you are talking about trillions of dollars in profits at stake in continuing business-as-usual consumption of fossil fuels until economically recoverable supplies are exhausted.

    “Moving to cleaner power generation” necessarily means a massive transfer of wealth from the fossil fuel corporations to other sectors of the economy that will be the foundation of the new industrial revolution based on harvesting an abundant, ubiquitous, endless supply of free energy from the sun, wind, tides, and the Earth’s internal heat, rather than on burning a limited, costly, destructive supply of fossil fuels.

    That transition is what some people say is a “threat to liberty”.

    And that’s the whole reason for the generation-long campaign of deceit and denial by the fossil fuel corporations: to delay the inevitable transition to a post-carbon energy economy as long as possible. Every single day that that transition can be obstructed and delayed means many millions of dollars in profit for the fossil fuel industry.

  16. 66
    Lennart van der Linde says:

    On potential sea level rise: it takes time for the ice sheet to start disintegrating and we don’t really know how fast this could happen. Pfeffer et al. estimate 2 meters is the maximum SLR in 2100. At that point the disintegration would be up to speed and 4-5 meters SLR in 2200 and 7-9 meters in 2300 would seem possible, or maybe even more according to Jim Hansen and others. In the past about 5 meters of SLR per century appears to have happened for several centuries. How can we know for sure this will not happen again beacause of AGW?

    These kinds of risks should be explicitly taken into account when we make decisions now that could have these kind of consequences over the coming centuries. From a science point of view the uncertainties in our knowledge are important. From a policy point of view the risks and the precautionary principle are even more important. In military planning the risks of worst-case scenario’s are crucial:

    So it’s important for scientists, policy makers and the wider public to communicate clearly on what the various risks seem to be, including those of large and rapid SLR over the coming centuries. Precaution demands we should minimize this risk as much as possible.

  17. 67
    Guy says:

    It’s a really sobering report, high on observed data (which is very timely). It certainly helps put things in perspective.

    Forgive for referencing the UEA hack, but I guess what a lot of the general public (to whom this report is partly aimed) need to know is that the underpinning here really is solid. For example, on P14 we read that “No credible scientific literature has been published since the AR4 assessment that supports alternative hypotheses to explain the warming trend”. I guess the question will arise – credible in whose eyes? If there is a suspicion that peer-review has become tainted, with referees appointed by authors, there exists a mechanism by which good science with different hypotheses could be excluded.

    Don’t get me wrong – my gut instinct strongly tells me that this report is accurate and true. But I don’t want to rely on instinct – I need to rely on the scientific method alone. Eric, I’d be grateful if you could add some thoughts on why the public can trust these conclusions from these scientists. Rightly or wrongly, public trust is at a very low point right now. Maybe it’s the lack of solar forcing? (poor climate science joke…)

  18. 68
    Spaceman Spiff says:

    A couple of well-written articles appearing on this website should help dissipate the fog of confusion swirling around the “saturated” carbon dioxide absorption ‘argument’.


    In particular one should read the discussion of the two figures of CO2’s absorption spectrum that appear about half way down the second of the two articles.

  19. 69
    Hank Roberts says:

    Good pointers, Ike.

    Searching Google for ‘Knorr airborne fraction 2009’ finds:

    Is the airborne fraction of anthropogenic CO2 emissions increasing?
    W Knorr – Geophysical Research Letters, 2009 –
    Several recent studies have highlighted the possibility that the oceans and terrestrial ecosystems have started loosing part of their ability to sequester a large proportion of the anthropogenic CO 2 emissions. …

    ►Irreversible climate change due to carbon dioxide emissions
    S Solomon, GK Plattner, R Knutti, … – Proceedings of the National Academy of Sciences, 2009
    … This can be easily understood on the basis of the observed instantaneous airborne fraction (AF peak ) of ≈50% of anthropogenic carbon emissions retained …
    Cited by 53

    No citations for the first; 53 for the second.
    Hmmmmm. Did anyone understand this, from Knorr?

    “the statistical model of a constant airborne fraction agrees best with the available data if emissions from land use change are scaled down to 82% or less of their original estimates”

    (The second paper cites an earlier Knorr paper, by the way)

  20. 70
    Spaceman Spiff says:

    The link to David Archer’s atmospheric radiation model mentioned by Spencer and Ray at the end of the first article mentioned in #67 is broken. It can now be accessed here: . Very instructive.

  21. 71
    Jim Bouldin says:

    How would you adjust this paper if you had to throw out any reference to Mann, Briffa, Jones, or any papers co-authored by them?

    How would you adjust the deniers arguments if you threw out ad hominem attacks, innuendo, red herrings, and insecure arrogance disguised as populism?

  22. 72
    Andrew says:

    Re: conversations on sea level rise

    It frustrates me that people seem unable to empathize with those affected when it comes to sea level rise impacts.

    I live on the Texas coast and we and neighboring Louisiana face the loss of well over a million acres of incredibly beautiful and productive coastal wetland this century. A meter rise will do almost all of it in.

    These marshes are home, work and life to a lot of people. We can raise our homes or move inland, and we can protect our cities with dikes and pumps, but there is nothing that can be done to save the natural environment in the face of such massive sea level rise. Diking marshes them and cutting them off from the sea renders them useless for marine life. Our tidal regime is too small (less than half a meter) to allow tide gates to function (i.e. close only at high tide).

    Pumping sediment into degraded and lost marshes is already occurring on a massive scale. We will embark on a 5 million dollar project this spring to pump sedimet and raise (restore) less than 500 acres of marsh. This will restore but a fraction of the 30,000 acres (12,500 HA) of tidal marsh lost last century in a single embayment.

    These marshes and bays developed over the last 6,000 years of stable sea level through sediment accumulation. In most cases they won’t simply move upslope.

    We’ve already committed to losing most of these marshes and bays. It has already been too much, too fast.

  23. 73
    Bill says:

    Can someone explain to a ‘non-climate’ scientist but a scientist nonetheless, the relationship (if any) of the GISS dataset to the HADCRUT ? Do they use the same surface station data, at least in part?

    [Response: Yes. The base of the all the temperature record analyses is the GHCN data (publicly available from NOAA) which is an assemblage of all the CLIMAT monthly reports put out by the national met services. GISTEMP augments that with some data sets from Antarctica and the better quality USHCN data (for the US only). HadCRU uses a small amount of additional data they obtained directly from the met centers (and which are the cause of the current trouble). The processing of the data differs, impacting mainly how the Arctic is covered. The year-by-year correlation is something like 0.97. – gavin]

  24. 74
    Bill says:

    re#73, I thought that was the case, so its not surprising to see the ‘correlation 0.97’, and the raw datasets are not really independent ( partial maybe…).

  25. 75
    Joe Horvath says:

    Re #65 by Secular Animist

    You can also add in the decline in asset values should a carbon trading mechanism or carbon tax be legislated. It’s not just the Exxon Mobils and other oil companies, it is going to have a major impact on any electricity generators with coal fired assets. Add up the expected decline in asset values and I daresay that it will swamp the likely loss in oil revenues by an order of magnitude.

    What I’m getting at is that there are some very large companies (and a lot of them) with very strong financial incentives to preserve the status quo.

  26. 76
    andy says:

    Unfortunately you guys (and the IPCC) have lost much credibility, based on the leaked emails and your own comments in response. As implied by your own admission, you only transmit signals that suit your agenda, and define any other signals as noise to be filtered out. Citing RealClimate as an authority is no longer effective in our arguments against the skeptics. They just come back with your loss of credibility.

  27. 77
    Brad says:


    I believe it would be useful to reproduce a graph of the Briffa 1998 Nature paper that shows the tree ring data and the instrumental data side by side. You can also reproduce Figure 5. from Mann et al. showing the graph where the x axis goes to 1960. Here’s why. From your explanation from several days ago I was unable, not being versed in climate science, to devine what exactly the issue was. It is widely believed that data is being “hidden” in the sense of “persistently covered up”. After looking for myself at the Briffa(1998) and Mann (1999) paper that the data is clearly in the public record. Nothing is being suppressed. Second, I think the correct way to describe what Mann et al. did was to “omit” data rather then “hide” it or even “hide it in plain sight”. Because (correct me if I’m wrong) it isn’t in plain sight, at least in the Mann paper — it’s omitted. Then, I would suggest a lucid high school level explanation (defining terms, e.g. “proxy data”) of why the tree ring data post-1960 is unreliable. Saying “Briffa says to do so” or “go look at this review” is welcome but it is not going to persuade anyone who is not already inclined to track down scholarly articles. Indeed, without access to a university library many readers will not be able to download the relevant review.

  28. 78
    Jere Krischel says:

    Are all the sources of data and computer programs used to generate this report freely and publicly available? In specific, not just in general (i.e., knowing that station data came from set A or set B does not tell you what parts of set A or set B were used). Put another way, could someone else replicate this paper based on the raw source data and programs?

    [Response: This isn’t a paper, it’s a summary of others papers. If you want the original data for those papers, you have to go back to the original sources.–eric]

  29. 79
    dhogaza says:

    I thought that was the case, so its not surprising to see the ‘correlation 0.97′, and the raw datasets are not really independent

    How could they be? They’re analyzing meteorological records, for instance the daily temperature readings at PDX near where I live. Neither organization reads that thermometer, rather they both are given the thermometer readings by the NWS.

    If you want independent data, look at the satellite record, which goes back thirty years.

  30. 80
    Paul Schmold says:

    Hey, long time creeper, first time poster here.

    Sexy report. You can tell it is aimed more at the general public and has an even more urgent tone than the AR4 report. I like the inclusion of the hockey stick graph will full discussion of any criticisms (valid or not).

    My only quip would be with the way the Greenland melt area is depicted in the two illustrations. The choice of 1992 could be viewed as a cherry-pick to enhance the effect, no? Wouldn’t Pinatubo have had a significant impact on that year? I don’t come from a physical science background so I could be way off. Not a huge deal, just kinda jumped out at me as odd and didn’t really add much value.

    Great stuff. Best of luck in Copenhagen.

  31. 81


    Check figure 10.13 of WG1, surprisingly you will find projections of Antarctic sea ice.

    [Response: Mea culpa. But it also says “There is a projected reduction of sea ice in the 21st century in both the Arctic and Antarctic with a rather large range of model responses. The projected reduction is accelerated in the Arctic [not in the Antarctic]..” I don’t see a problem here.]

    I have written a short article about the published comments on Rahmstorf 2007, as well as some further analysis that I did here. I would very much be open to understanding if I went wrong somewhere. All I got earlier was a pointer back to a graph in Rahmstorf’s reply which doesn’t answer the issues raised.

    Finally in the graph of sea level projections it only shows a range in 2100 for one other study, which appears to be substantially below the Rahmstorf estimate. Yet the author’s chose to show the high end of the Rahmstorf estimate as the high end of the range. I haven’t had a chance to review that paper yet.

    [Response: Right, the high end is the high end. Why is that a problem?-eric]

  32. 82

    Jim Bullis,

    You are technically correct, but I believe that large power plants convert fossil fuels into energy far more efficiently than internal combustion engines. Thus it is my understanding that electric vehicles produce less CO2 in their operation, than internal combustion driven automobiles.

    Whether there are separate issues in manufacture is a separate question.

  33. 83
    Jere Krischel says:

    [Response: What you are implying is that “The costs of doing something about global warming are greater than the benefits of doing nothing.” Evidence, please? (Oh, and *where* do you get the idea that there will be more arable land?!)–eric]

    Isn’t the question better pointed in your direction, eric? What evidence do you have that a warmer world is worse for people, especially since we’ve already had that in the medieval warm period? I think the original point is that there is an open question there, not that they know the answer. It’s quite possible that the answer is unknowable, given all the variables involved with technology, politics and plain human error.

    You seem to be making the point that the benefits of reducing CO2 emissions outweigh the costs. Can you provide some evidence for that?

  34. 84
    eric says:


    If you have something to say usefully about the report itself, feel free. Comments regarding conspiracies, collusions, etc. are going to be deleted, whether supportive or not. This is off topic. You can post those elsewhere under the “CRU Hack” section if you must.


  35. 85
    Ike Solem says:

    Small typo there, Chip:

    “Do you even understand why the ratio of highs and lows is expected to be constant if the planet is in steady-state equilibrium?”

    Should be “Do you even understand why the ratio of record highs and lows is expected to be 1:1 if the planet is in steady-state equilibrium?”

    Answers here.

    Bonus question:

    Why does the “1 in 1000 year” statement by the Britain’s Environment Agency on the record flooding in northern England represent an a priori assumption that the climate has been stable for at least the past 1000 years, and has not changed in the past century either?

    Could it be possible that what was once a 1 in 1000 year event is now a 1 in 20 year event, or even more frequent? How would one know? Well, if there is a long-term trend showing an increasing ratio of highs to lows, and this means warmer winters, meaning more evaporation, not less, correct? I’d be guessing that would lead to more flooding, perhaps in pulses. The models are far more reliable on temperature predictions than on precipitation predictions, but there is also a ratio to look at, precipitation-to-evaporation.

    How would that work? Consider warm wet air rising in the tropics:

    We can think of parcels of air leaving the boundary layer for the free troposphere carrying large boundary layer mixing ratios, condensing and precipitating much of this vapor, and returning with much smaller vapor content…

    A very important consequence of the increase in lower-tropospheric water is the increase in horizontal vapor transport within the atmosphere…For Fig. 5b, we locate the midlatitude maximum in the annual-mean poleward moisture transport in each model (and each hemisphere) and plot the fractional change in this flux at this latitude in the A1B scenario, as a function of the change in global-mean surface temperature. Despite some scatter, the correlation is clear, with a slope of roughly 5% [per Kelvin].

    Held&Soden 2006, Robust Responses of the Hydrological Cycle (197 citations)

    So, the models do predict more precipitation in wet areas, and more evaporation in dry areas, with a generally higher level of water vapor in the troposphere. As Northern Europe and Britain cool each winter, this could easily result in record rainfalls, and hence record flooding.

    That, as you are probably thinking, is just a model result. What about the data? Try this:

    The largest change is in the average amount of precipitation on those days that it does rain, which shows an increase across the entire UK.

    You’re not going to argue that because of the hacked emails, the precipitation data for Britain, 1961-2006, is somehow no longer accurate? Not much logical connection there – but no shortage of potential innuendo, right? Which is about all the denialist lobby is left with.

    To sum up: It’s probably a bad bet to assume that this kind of flooding in northern Britain won’t happen for another 1000 years.

    P.S. via wiki- Galen Strawson wrote that an a priori argument is one in which “you can see that it is true just lying on your couch. You don’t have to get up off your couch and go outside and examine the way things are in the physical world. You don’t have to do any science.”

  36. 86
    The Wonderer says:

    The explanation of the CO2 “fog layer” is interesting and my take take on it a bit different than I understood it before. If I understand correctly, average temperature gradient in the lower atmosphere is basically set by the pressure gradient, and the equilibrium point by the concentration profile of GHGs. I am a bit confused and trying to reconcile this with the explanation in the RC “Why does the Stratosphere Cool” post. It seems the temperature gradient increases above the equilibrium point and is fixed below it? What is the driving factor in the gradient change above the equilibrium point?

  37. 87


    There isn’t a problem. I just pointed out that Antarctic sea ice is well above the projection. While Arctic sea ice is below. In the Cohpenhagen report summary the author’s focused on the Arctic sea ice and didn’t mention the Antarctic. This is the kind of cherry picking that I was referring to. A more balanced summary would be more powerful in my opinion.

    [Response: No, what you are doing is cherry picking. Those who work on sea ice understand perfectly well the vast differences between Arctic and Antarctic sea ice. The reason I assumed IPCC hadn’t done projections for the Antarctic is because I know (and the IPCC authors, of which I’m not one, know) that we can’t do that with any reliability. Antarctic sea ice (unlike Arctic) is a question of winds, and thermodynamics barely come into it, which makes it quite a lot harder. Again, there *is* a section on Antarctic sea ice, and it is perfectly clear, and accurate. You are looking for things to complain about. Any fool can do that, and most fools do.–eric]

    On sea level. I suppose that if you say that the projected range is the high and low range of all studies the figure is fine. But a reader might believe that this is some kind of consensus view, and I don’t think that it is.

    Finally I would really enjoy understanding if I went wrong in my observations about Rahmstorf 2007. My feeling is that it simply doesn’t meet the out of sample test, as the published comments stated, and as I further elaborated in my short article. I would have been happy to submit for peer review, but I think you would agree that it is unlikely that a journal would be interested even if I am correct. So as an alternative I ask you to review it. I would be happy to do it by email if that is preferable.

    [Response: I will take a look at some point when I have time, but you’d do better writing directly to the author himself. And journals would certainly be interested if you have something credible to say.–eric]

  38. 88
    Ike Solem says:

    P.P.S. The lack of a preview option is a bit problematic…

    Let’s not forget what the first discussion at Copenhagen will be about, either:

    “At Copenhagen, the first decision on technology will be to decide if a new co-ordinating body should have powers to command the clean tech roll out. “The G77 [group of developing nations] and China have proposed a new central executive, political body,” said Tomlinson. It would be part of the existing UN Framework Convention on Climate Change, which administers the Kyoto protocol.”

    “However, Europe and the US want only an advisory committee – their main concern is that a strong political body may end up channeling funds into state enterprises rather than keeping a level playing field for all businesses. Developing countries say an advisory body would have little power to drive the dramatic changes needed.”

    The idea behind a transition to renewables is actually to re-level the playing field by removing the subsidies that fossil fuels have exclusively enjoyed for the past few decades – and – to make up for that market distortion – give them to renewables instead. If true-cost accounting is also implemented for fossil fuels, then you would have a level playing field – something which doesn’t exist now.

  39. 89
    Sloop says:

    During my first look through Copenhagen Diagnosis, my first thoughts were-

    If you’re religious, start praying or chanting, . . . hard.
    If you have young children, hug them tonight.
    If you have a pulse, start thinking about what you can do to prevent the worst from happening.
    . . . . then I cried.

  40. 90
    Icarus says:

    The report says:

    “If global warming is to be limited to a maximum of 2°C above pre-industrial values, global emissions need to peak between 2015 and 2020”

    Presumably this is based on a climate sensitivity of 0.75ºC/W/m2) meaning that with current anthropogenic forcings of 1.6W/m2 we should expect 1.2ºC of warming (of which we’ve seen about 0.7ºC so far) but Hansen suggests here:

    … that it’s actually more like 1.5ºC/(W/m2), meaning we’re already *above* the level of CO2 which would eventually yield 2ºC (1.6 x 1.5ºC/(W/m2) = 2.4ºC). Does the report reflect a consensus view that Hansen’s 1.5ºC/(W/m2) is unlikely? Or is it just a question of timescale (i.e. if it’s going to take 1,000 years to get to 2.4ºC then we’re not going to worry about it now)?


  41. 91
    Hank Roberts says:

    I can only try to guess what The Wonderer 24 November 2009
    is talking about, without a pointer to wherever that’s from.

    I’d guess he’s asking why a troposphere.

  42. 92
    Edward Greisch says:

    The full report is too big for this machine. The summary is plenty scary. 7 degrees C is one more than the for-sure extinction point for Homo Sapiens as reported in a bunch of reports and books.
    The book “Six Degrees” by Mark Lynas says: “If the global warming is 6 degrees centigrade, we humans go extinct.” See:
    Lynas lists several kill mechanisms, the most important being famine and methane fuel-air explosions. Other mechanisms include fire storms.

    The following sources say H2S bubbling out of hot oceans is the final blow at 6 degrees C warming:
    “Under a Green Sky” by Peter D. Ward, Ph.D., 2007. is a NASA web zine. See:

    “Climate Code Red” by David Spratt and Philip Sutton says the following:
    Long term warming, counting feedbacks, is a least twice the short term warming. 560 ppm CO2 gets us 6 degrees C or 10.8 degrees F. We will hit 560 ppm before mid century.

    Per “Climate Code Red”, we need ZERO “Kyoto gas” emissions RIGHT NOW and we also need geo-engineering because we have already gone way beyond the safe CO2 level of 300 to 325 ppm. We are already at 455 ppm equivalent and we have tripped some very big tipping points. We aren’t dead yet, but the planet needs critical intensive care if we humans are to have a chance of survival.

    “The Vanishing Face of Gaia” by James Lovelock has identified a 9 degree lurch in the temperature that happens at 450 ppm equivalent.
    Looks like we are not going to make it. We HUMANS could be EXTINCT by 2050 because politicians are not considering sufficiently strong action.

    Thank you, RealClimate, for this last-ditch effort to save us from extinction. All readers should forward RealClimate’s email to their politicians immediately and call their politicians in the morning.

  43. 93
    dfree says:

    …am a bit curious if any of the persons on this site have any feelings about this link I have posted above?
    ..As this may offer an alternative explanation to what the current consensus is….Just maybe the info on this site, could help anyone with other plausible reasons of ice sheet/ perma frost/artic ice declines..

    Funny, but I never read any info here,that includes the contribution natural events may have in the spike of CO2 measured in the last 60 yrs? A spike of some 50 “p.p.m.” like ..say “volcanoes”…I feel they have been over looked and not included in the equation of the composition of the aggregate amount of CO2, measured to date..that is attributable to human activity! last count was less then 4%!!..seem rather small to be getting excited about..or even re-engineer the last 12o years of how this country does business?

    As for the hacked emails? there may be a bit more effect on the “global warming fraternity”..keep the faith fellas!! there is now a “vail of impropriety”..and and this vail is has of today become a “BLANKET”…dump any “green stock” you may have aqquired..if not tomorrow..soon!!

    I love this site

  44. 94
    The Wonderer says:

    I’m asking what drives the change in gradient in the stratosphere with increased CO2. I’m referencing the “fog layer” explanation in the Copenhagen Executive Summary and the RC post on “Why does the stratosphere cool when the troposphere warms?” The explanations seem somewhat different to me, and somehow it made more sense to me when I understood that the temperature gradient would be increased at all layers due to increased GHG. My understanding of the recent explanation is that is not so in the lower atmosphere.

  45. 95

    Can you please point out anything in section that says that the Antarctic projections are less certain than the Arctic projections?

    What journal do you believe would be interested in a criticism of the Rahmstorf article? There have already been comments and responses published. It resolved nothing. I’m not making a new projection, just commenting that a linear model based on temperature doesn’t work, which is hardly a revelation.

  46. 96
    Joel Shore says:

    Eric et al.: Nice job on the report. I have only had time to read parts of it, but I was quite impressed in particular with the gray boxes that deal with questions like “In climate history, didn’t CO2 change in response to temperature, rather than the other way round?”, “Isn’t climate always changing, even without human interference?” and “Are we just in a natural warming phase, recovering from the “little ice age”?” These are common questions that all of us who have to communicated with skeptics or the public at large have had to answer many times but I thought that you did a particularly nice job in addressing them.

  47. 97
    Patrick 027 says:

    Re 46 Ryan O –

    “As the surface temperature of the earth increases, however, the outgoing radiation also increases, and stratospheric temperature begins to recover.”

    This is quite true; however:

    “At equilibrium, the outgoing radiation will be the same as what it was prior to the stepwise change and the stratosphere returns to (approximately) the same temperature prior to the perturbation.”

    This is not necessarily the case, and actually, … well maybe it depends on how you compare before and after. The tropopause height rises. I’m not sure … maybe if you measure height from the tropopause, the two equilbrium temperature profiles above the tropopause (setting aside seasonal and regional variations) would match up or roughly so (?concievably?), but comparing the temperature profile at the same pressure level in the atmosphere, you would find the two equilibriums differ in opposite ways between the troposphere and stratosphere.

  48. 98
    Jere Krischel says:

    [Response: I will take a look at some point when I have time, but you’d do better writing directly to the author himself. And journals would certainly be interested if you have something credible to say.–eric]

    The CRU emails, and the presupposition that anything that challenges the AGW theories is a priori not credible, makes people wonder if journals really are interested in corrections. Your replies are greatly appreciated.

    [Response: Have you tried? Or are you just making presuppositions?–eric]

  49. 99
    TD says:

    I was following Gavin S’s responses here on RC and I appreciate his and RC’s responses to a difficult situation.

    One of the things Gavin had said to the posters is that when smoothing proxy data to modern measurements is that any graph should note that clearly. I think this is the “trick” (not a trick, a solution) to “hide the decline” (smoothing the divergence problem). Perhaps, me, being a neophyted, I have twisted myself.

    Reading the Cop Diagnosis, I notice that on page 52, figure 21, it does not explain that problem. Can you comment?

    [Response: Simple. All the complaints are about many years old. The figure in the report doesn’t use any such smoothing.–eric]

  50. 100
    oracle2world says:

    By the way, all this talk of “extinction” seems kind of overblown, wouldn’t you say? Mankind lives in the Antarctic and outer space. Bacteria live in reactor cooling water (and hot springs).

    The earth came back from a meteor strike 65 million years ago. And despite the best efforts of mankind to exterminate cockroaches, mosquitoes, etc. they are still around.

    So now everything is on the brink of irrevocable extinction because of SUV exhaust?

    The Asch psychology experiments showed conclusively that people will knowingly lie to be conformist. That experiment compared two lines on a piece of paper. No ambiguity.

    The Inquisition, Salem Witch Trials, Hitler, Sen. Joe McCarthy … you would think educated folks would recognize the latest and greatest incarnation of this phenomenon. But they don’t. Even when in your face.

    There is also another interesting result from psychology – “cognitive dissonance”. When confronted with events that contradict belief, the beliefs just get stronger. If CO2 really isn’t the End-of-The-World-As-We-Know-It … it just reinforces believe in those that do.

    Anyway, feel free to munch on these comments without response. It is a lot to get a grip on, all at once.

    [Response: That’s enough. Let me be very clear here: The apologists for McCarthyism were folks of the same breed as those who are trying to discredit scientists by painting them as leftist conspirators. That’s exactly what you are doing now. Some of us are old enough to have been there during that era. Some of us had relatives and friends that were subjected to the hysteria of the anti-government, anti-civil liberties, fearmongering red-scare crowd, led on by Nixon, McCarthy and their ilk. How dare you. How *dare* you brand academic scientists this way. How *dare* you!–eric]