Copenhagen

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 www.copenhagendiagnosis.org. 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 comments on this post.
  1. Bill:

    In view of this impending potential disaster and the syated need for urgent actions, I would suggest that >95% of the planned attendees at Copenhagen cancel their trips, stay at home and use the internet and save untold amounts of CO2. The need to set examples needs to start here !

  2. James Allan:

    Nice work. One thing I like is the big emphasis on observational data; thinking back to the the time of TAR, one of the most common (largely misguided) complaints from the sceptics was that climate science entirely relied on models and that the of the prophesies of doom were nothing more than hyperbole. Now that we have so much more data, that line of argument is more or less defunct and I think the balance in this report is a good reflection of that.

    [Response: Thanks, yes. I think that is a real strength to the report. The raw observations speak pretty loudly, and as Lonnie Thompson likes to say, the data have no political agenda.--eric]

  3. DavidCOG:

    The perfect response to the stolen emails sideshow.

    Thank you to all the hard-working, serious scientists that contributed and who are helping us understand what is happening to the climate.

  4. David Hutton-Squire:

    Instead of the non-existent http://www.copenhagendiagnosis.org/ under the logo at the top, you clearly meant http://www.copenhagendiagnosis.com
    Thanks for the (almost) pointer.

    [Response: Works fine. There may have been some delay in the updating of .com-->.org after the initial release.--eric]

  5. Chris Dudley:

    I found the projection of a 40% loss of permafrost by 2030 regardless of emissions scenario to be something that could use more discussion. This seems like a large potential feedback in the near term that should be quantified. What would happen if we stabilized at 350 ppm early, say in the 2040′s? There are emissions scenarios that have not been explored yet.

  6. Chip Knappenberger:

    Eric,

    As you may or may not know, I am currently working on trying to properly compare observed global temperature trends during the past 5-15 years with model projections during similarly short periods—a less than straightforward endeavor. So I am somewhat familiar with the behavior of recent temperatures.

    The CopenhagenDiagnosis seems at odds with at least my interpretation of recent events. For instance, try as I may, I cannot seem to reproduce Figure 3 (top) from the CopenhagenDiagnosis report from the tool for plotting temperature trends available at NASA GISS. For one thing, I am not sure why the report which is intended to provide the most updated information only shows the trends (in Fig 3top) through 2007, when annual data through 2008 is readily available from GISS (in fact Fig3 bottom uses data through August 2009). But whether I use data from 2001 through 2007 or 2008, the trends map I produce from the GISS site is much different from the one depicted in their Fig 3 top. Perhaps I am doing something wrong.

    And the general handling of whether models are correctly capturing recent temperature changes is given a rather less than robust handling in the section “Has global warming recently slowed down or paused” (p. 15). The observed temperature behavior is a bit less simple than presented (for example, see my discussion here). And only about half the difference in short-term temperature trends between the GISS and the CRU data can be explained by coverage differences (so the difference is not as readily swept under the rug as the CopenhagenDiagnosis indicates). Further, there is virtually no discussion about how well models capture the shorter-term temperature trends, say during the period 2001-present (the period depicted in Figure 3 top). During this period, it is less clear that the models, which include natural variability, are accurately capturing what is going on. For instance, Knight et al. (BAMS 2009), which has overly wide confidence intervals because they include variability besides weather noise, show that the observed trend falls out on the lower shoulder of the HadCM3 projected trends. In my investigations, some other climate models don’t fare as well as the HadCM3 (nor does the HadCM3 fare as well when variability is properly constrained).

    So, in my view, the point that you highlighted “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” is not well-supported.

    -Chip

    [Response: Chip: Why on earth are you trying to "compare temperature trends during the past 5-15 years with model projections during similarly short periods". That's a pointless, fruitless, silly exercise. Models reproduce well the statistics of stochastic climate variability, not the details. Homework: Read page 13 of the report again.--eric]

  7. sascha:

    First, I’d like to thank the authors for taking the effort to present the facts in such a way that non-scientist like myself can understand them. Also, thanks for making the whole report available online and free of charge.

    Still, I was a little disappointed:

    Just when I was convinced I was actually reading a non-alarmist, non-political fair summary on the most recent state of knowledge of climate science, I came accross page 51 (chapter “The Future”) where it says:

    “[...] global mean warming of even just 1.5-2.0°C still carries a significant risk of adverse impacts on ecosystems and human society. For example, 2°C global temperature rise could lead to sufficient warming over Greenland to eventually melt much of its ice sheet (Oppenheimer and Alley 2005), raising sea level by over six meters and displacing hundreds of millions of people worldwide.”

    …even though page 31 (chapter “Global Sea Level”) clearly states two meters as the upper (!) limit for 2100.

    So I assume this means the “six meters” mentioned here could, if ever, only be reached gradually over the course of several centuries or even milennia into the future – a time span for which:
    a) no credible meaningful climate predictions can be made, even with todays most sopisticated computer models (please correct me if I’m wrong), and
    b) for which “displacement” is a rather nonsensical concept, as over the course of many generations, civilisation and the way it uses the earth’s surface will gradually evolve/shift anyhow and no individual will nececcarily ever be “displaced” by this shift.

    Therefore, I feel that even though it might be scientifically correct that 100% of Greenland’s ice melting would theoretically correspond to 6 meters in sea level rise, it’s rather dishonest to phrase it like it was in the report, pretty much using it as an excuse for introducing the alarmist notion of iminent massive human tragedy.

    I can already picture in my mind tons of press releases/articles by Greenpeace, Time magazine, etc. where the only words they will quote from the this report will be:
    “raising sea level by over six meters and displacing hundreds of millions of people worldwide”.

    Was this really necessary?

    [Response: Not every sentence in the report is going to please everyone. But there's nothing 'alarmist' here. 'Merely' 1 m by 2100 is going to have a huge impact, itself displacing hundreds of millions of people. And yes, 'displacing' is exactly what we're talking about (people will have to move to another place). And it's not just the third world either. Ever flown into Vancouver, BC? You'll still be able to land at the Vancouver airport after 1 m of sea level rise .... if you have a seaplane. Finally, tme will keep marching forward past 2100. --eric]

  8. DrCarbon:

    Eric, Looks like your time stamp is off as this was posted under Nov 21 instead of Nov 24. FYI.

    [Response: Fixed, thanks.]

  9. dhogaza:

    So I assume this means the “six meters” mentioned here could, if ever, only be reached gradually over the course of several centuries or even milennia into the future…

    Well, yes, that’s what “eventually” vs. “by 2100″ means. Clear as day to me.

    Therefore, I feel that even though it might be scientifically correct that 100% of Greenland’s ice melting would theoretically correspond to 6 meters in sea level rise, it’s rather dishonest to phrase it like it was in the report, pretty much using it as an excuse for introducing the alarmist notion of iminent massive human tragedy.

    You’re reading something into it (“imminent”) that’s not said. I suppose they could preface each paragraph with “please read carefully and take care not to misconstrue what we say”, but even that probably wouldn’t prevent misreadings.

  10. sascha:

    Well, yes, that’s what “eventually” vs. “by 2100″ means. Clear as day to me.

    As long as “eventually” is not defined in any way, it isn’t that clear to me.

    You’re reading something into it (”imminent”) that’s not said.

    Well, they do use the statement in the context of warning about mass “displacement” – a phrase that implicitly carries with it the connotations of “catastrophe” and “short time span” (as I stated before, it doesn’t make sense when looking at long time spans).

    That’s what I ways trying to say.

    [Response: Sascha: Fair enough, and I appreciate your balanced tone. However, you should recognize that while it is virtually certain that business as usual scenarios will eventually destroy the Greenland ice sheet, the timescale for this remains very uncertain. So all we can really say at this stage is "eventually". We don't use the word "catastrophe", and I agree that would be a loaded an inappropriate term.]

  11. dhogaza:

    Well, they do use the statement in the context of warning about mass “displacement” – a phrase that implicitly carries with it the connotations of “catastrophe” and “short time span”

    Short time span when they explicitly discuss two meters, not six meter, as the maximum possible sea-level rise by 2100?

    C’mon … it’s obvious that “eventually” means “long after 2100″, in context.

    Of course, I’m a native speaker of English, while the name “sasha” implies that maybe you aren’t, but still, you’re adding a lot of personal prejudice into the words that were actually said.

  12. pete:

    I think Jaxa might diagree with your Arctic Sea ice declining mantra….minimum this year over 1 million sq km above 2007 and second straight year of recovery………..
    http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

    [Response: The relevant part of that figure is where 2009 intersects with Sept -- around 5.5 million km2. Put that data point on the graph (Figure 13) in the report.-eric]

  13. Chip Knappenberger:

    Eric, Re#6 comment,

    Ok. I went back and reread page 13. Is Figure 3 top correctly captioned?

    If assessing model behavior over the short term is a silly idea, then why are there so many references on page 15 about 10 year trend values? Why not 8 or 9 year values? Knight et al. looked at trends from a short as 2 years! Apparently the reviewers didn’t reject that paper as being a “pointless, fruitless, silly exercise.” Why not?

    -Chip

  14. Chad:

    The models actually track temperature trends since 2000 quite well (using Santer’s method of comparison). Redo the analysis starting with 2001 and you get different results. Just goes to show you that such analysis over a short period of time is not robust. I’ve got all the results up for those interested.

    http://treesfortheforest.wordpress.com/2009/09/26/ar4-model-hypothesis-tests/

  15. Tonyb:

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

    Where? Please cite a reliable source.

  16. Steve Bloom:

    The problem is that the possibility of a short-term large response from the GIS can’t yet be excluded.

  17. Chip Knappenberger:

    Chad, Re14:

    If models were getting things right (including weather noise), then the observed trends would be contained by the models at all time frames. That they are not, is a robust result that the models (or at least some of them) aren’t working right.

    -Chip

  18. Mark Gibb:

    My problems with the AGW community do not involve the slow, methodological plodding of good science, it is the alarmism that is desired by politicians so they have the cover they need to empower themselves.

    I am reading the report now, so I cannot yet comment on the contents, but by first impressions, it looks to me that the “sky-is-falling” tone is the first thing someone sees when they look at the cover. The images look like they could have been taken right out of a disaster movie, complete with what looks to me to be a computer-rendered angry-ocean picture.

    Just giving the customers what they are after, I guess.

  19. dhogaza:

    If models were getting things right (including weather noise), then the observed trends would be contained by the models at all time frames. That they are not, is a robust result that the models (or at least some of them) aren’t working right.

    This nonsense is the best denialist science can give us? Really? How disappointing.

  20. Eli Snyder:

    Re: 7

    Sascha, would you mind providing a definition of “alarmist?” I’m not clear on exactly what you mean by that. You seem to indicate that it means saying that there is “imminent massive human tragedy,” which is not entirely clear either — but let’s take “imminent” to mean “within the next century” and “massive” to mean “affecting very large numbers of people” (say, more than a few million) and “tragedy” to mean “something that would severly adversely affect their lives”(for example, turning them into refugees). Those sound like reasonable definitions.

    In that case, even under conservative estimates (only 1 meter of sea level rise) we are facing “imminent massive human tragedy” just from sea level rise alone, and that’s only one of the many projected adverse effects even with relatively mild warming.

    If that’s the definition of “alarmist” then even the most conservative projections of what will happen on the current emissions path are “alarmist,” so it becomes a pretty meaningless term.

    Is there something else you mean by it?

  21. llewelly:

    sascha says:
    24 November 2009 at 1:07 PM:

    Well, they do use the statement in the context of warning about mass “displacement” – a phrase that implicitly carries with it the connotations of “catastrophe” and “short time span” (as I stated before, it doesn’t make sense when looking at long time spans).

    “displacement” is a neutral term that is widely used for both slow and rapid movements. It does not imply connotations of “catastrophe” or “short time span”.

  22. tharanga:

    On page 12, Canadell et al (2007) is cited as showing an increase in the fraction of CO2 that stays in the atmosphere, over the last 50 years. It is noted that there is a good deal of uncertainty in this estimate, due to interannual noise and uncertainty in the extent of land use changes.

    Since then, Knorr (GRL, 2009) has done his own analysis, attempting to account for uncertainty in the data, and saw no significant trend over that time period. I’m assuming the more recent paper was simply too recent to consider for mention in this report. Given the uncertainties involved, I don’t think the two papers are really all that much in contradiction to each other, but I am wondering if anybody here would like to comment on the methodologies in the two papers.

  23. Nicolas Nierenberg:

    I don’t need to read the whole report to comment.

    1) The summary entirely focuses on the negative which is unscientific. For example Antarctic sea ice is above IPCC forecasts. Just a small example I realize but one I am familiar with.
    [IPCC did not make a forecast of Antarctic sea ice. Nor is the recent increase in any way in contradiction to what the models show.

    2) The fact that the sea level comments are almost entirely reliant on Rahmstorf 2007, which published comments showed had serious flaws is an additional sign of trouble.

    There is little question about the solidity of the science around climate change, which I believe would stand on its own without resort to hyperbole. This type of unbalanced report doesn't serve the purpose that the author's intend.

    By now you must realize that for a majority of thinking people including the political class it is clear that we should drastically reduce the amount of CO2 being emitted. The problem is economic and political not scientific.

    [Response: Umm.. Yes, you do need to read the report. IPCC didn't project Antarctic sea ice, and there is nothing contradictory about what is happening, vs. what IPCC said about Antarctica. The question of Antarctic sea ice is well addressed in the report. Nor does this new report rely entirely on Rahmstorf; other studies are in excellent agreement with his. What specific 'flaws' are you alluding to?-eric]

  24. Bud:

    @chip #13: I’m not an expert on the matter, but it seems fairly evident that whilst comparing a small (5-15 year) period with model projections over the same period is not terribly useful, comparing multiple 10 year (and, indeed, 2-3 year) trendlines across a longer-term period is a fairly common statistical technique. That’s certainly the difference between what you refer to as your own study and the work described on page 15 of the Copenhagen report.

  25. SecularAnimist:

    I should be used to it by now, but the reaction from so-called “conservatives” always appears utterly bizarre to me:

    1. Science tells us that we have a very serious problem — indeed, a grave danger to the continuation of human civilization — from continued anthropogenic GHG emissions and consequent global warming and climate change.

    2. Some people propose solutions to this problem that are not to the liking of “conservatives”.

    3. “Conservatives” respond not by proposing solutions of their own that are more to their liking, but by denying that the problem exists.

    Now, why is that? Is “conservatism” incapable of proposing solutions, leaving “conservatives” no choice but to bury their heads in the sand and pretend there is no problem? Thereby rendering themselves irrelevant and impotent and leaving the field of solutions to those who propose the solutions that they dislike? Wouldn’t “conservatives” be better off acknowledging the scientific reality of the problem and getting a seat at the table where solutions are being debated?

  26. tharanga:

    On page 13, the report mentions La Nina and the solar minimum in regards to 2008, and how the TSI was the lowest measured in the satellite record. While that solar minimum was lower than the other two solar minima, it’s not that much lower (expressed as a forcing) to be anything special, is it? Was that fact just tossed in there to tease the “it’s the sun!” crowd?

    Regarding how the solar cycle would show up in the temperature record: Fig 5 seems to take the solar cycle, convert it to an instantaneous forcing, and then further to an instantaneous temperature change. In an imaginary world with no other forcings and no ENSO, would the temperature history actually look like that in Fig 5, or would lagged response to the forcing smoothen out the variation?

  27. Chad:

    Chip-
    If the models were absolutely perfect, they still wouldn’t generate trends that encompass observations consistently over every small time frame like the one I mentioned. The models are first spun up to equilibrium then various forcing histories and scenarios are imposed. Thus the internal variability of a perfect model and observations aren’t necessarily going to be in synchronization. This asynchronization could strongly alter trend analysis results over short periods of time. The fact that the analysis starting in Jan 2000 shows no significant difference doesn’t vindicate the models. Just look at the size of those error bars. It’s weather noise that’s undermining the power of the test. And the fact that the results change significantly when shifting the start year to 2001 shows the analysis is sensitive to the endpoints and not robust.

  28. Hank Roberts:

    weblogplaza — the link behind “Nichols” –is a blogspam bot.

    [Response: thanks, deleted]

    > If models were getting things right
    >(including weather noise)

    Ah, yes, we should wait until we have much bigger and faster computers, and do nothing until we are able to model everything at the same time.

    “Delay is the deadliest form of denial.”

  29. sascha:

    @ eric, regarding displacement caused by rise in sea level by 2100:

    Ever flown into Vancouver, BC? You’ll still be able to land at the Vancouver airport after 1 m of sea level rise …. if you have a seaplane.

    Well, coming from an engineering background, I must say that totally depends on how much the Vancouverians love there airport… (that is, how much they are willing to spend on constructional measures…) ;-)

    But I do get you point of course… I also realise it’ll be a much bigger problem for the poorer regions of the earth…

    @ dhogaza, regarding a possible implied “short time span” for drastic sea level rise:

    You’re right, when taking the article as a whole, it will be clear that “eventually” must in this sentence refer to timespans longer than 100 years. I did point this out in my original comment.

    It’s just that when I read that sentence in the report, I personally felt that in the specific context it was in (that specific chapter/page, rather than the whole book) it sounded rather alarmist (as opposed to unemotional, fair presentation of scientific knowledge).

    I don’t know, maybe I did misinterpret the language a litte. I am indeed a non-native speaker (btw, I’m honoured you guessed it primarily from my name rather than from my writing), and yes, like everyone else I am not exempt from personal prejudice.

    Part of my personal prejudice may be negative experiences with statements publicized by overzealous environmental groups regarding global warming and similar topics – statements which I naturally believed at first – turning out to be really not much more than the most catastrophic-sounding paragraph of a reputable scientific publication quoted out of context. I personally believe that even if it is for a commendable cause, exaggerating scientific results, or deliberately presenting them in a dishonest alarmist way is not acceptable.

    But I guess I should really stop spamming this comment space with my personal sensitivities and make way for the more scientific discussions by some of the commenters here…

  30. tharanga:

    Re Pete, 12: So long as there is short-term variability in any data set, you can almost always try to claim that whichever variable (temperature, Arctic ice extent, whatever) is in “recovery”, so long as the most recent data point wasn’t the record high/low.

    But is there any value to making that claim? Is that really what you see, when you look at Fig 13?

  31. Jim Bullis, Miastrada Co.:

    The heart of the matter is the following pasted from the subject report (I use quotation marks to separate the exact report words from my comments.):

    “Is the greenhouse effect already saturated, so that adding more CO2 makes no difference?”

    Yes, that is the question.

    “No, not even remotely. It isn’t even saturated on the runaway greenhouse planet Venus, with its atmosphere made up of
    96% CO2 and a surface temperature of 467 °C, hotter even than Mercury (Weart and Pierrehumbert 2007).”

    Huh? Who the heck cares about Venus?

    “The reason is simple:”

    Sure it is (sarcasm drips from screen). Continue reading to see how a simple person comprehends this, thus demonstrating that it is not simple.

    “the air gets ever thinner when we go up higher in the atmosphere. Heat radiation escaping into space mostly occurs
    higher up in the atmosphere, not at the surface – on average from an altitude of about 5.5 km. It is here that adding more
    CO2 does make a difference. When we add more CO2, the layer near the surface where the CO2 effect is largely saturated
    gets thicker – one can visualize this as a layer of fog, visible only in the infrared. When this “fog layer” gets thicker, radiation
    can only escape to space from higher up in the atmosphere, and the radiative equilibrium temperature of -18 °C therefore
    also occurs higher up.”

    OK! But maybe a little more about the importance of the -18 deg C would be helpful.

    “That upward shift heats the surface, because temperature increases by 6.5 °C per kilometer as one goes down through the atmosphere due to the pressure increase.”

    Maybe the 6.5 deg C per kM is so, but not due to pressure increase. You can’t be serious that pV=nRT applies after millions of years of adjusting.

    “Thus, adding 1 km to the “CO2 fog layer” that envelopes
    our Earth will heat the surface climate by about 6.5 °C.”

    No, that layer will perhaps force the earth to be warmer in order to establish the -18 deg C through the fog layer. I can see that the earth surface needs to be more than the temperature of the lower most layer in order to get a net radiative heat transfer outward. I guess that rule would apply through successive infinitessimally thin layers all the way up to the final -18 deg C layer. So now if the earth gets 1 deg C warmer there should be significant heat transfer to the -18 deg C layer, and of course it would warm that layer causing higher rate of heat release. Since there is a 6.5 deg C difference, as that heat is released to bring things back to equilibrium, the earth surface would be returned to its original temperature.

    It looks to this simple folk (namely me) like there is something wrong here.

    [Response: I'll readily agree that the analogy in the report is a bit difficult to follow. However, it can't be so bad, as you seem to have understood the essential points. Your key misconception is encapsulated in your last sentence -- the surface temperature *does* return to equilibrium, but not to its original value. Adding more greenhouse gases means the equilibrium has changed -- the stratosphere cools (as has been observed), and the surface warms (as observed)-- until that new equilibrium (warmer surface, colder stratosphere) is reached.--eric]

  32. MapleLeaf:

    Have read the report. There is an incredible amount of science in there! What really stood out for me, in addition to the inclusion of more and more observational data sets, is that the IPCC projections of sea level and Arctic sea ice minima have been way too conservative. So much for IPCC “alarmism”. It seems the biosphere is going to alarm us if anything in its rapid response to the anthro forcing. Given the third lowest minimum this past summer, and very slow growth of the ice in October and November, the stage has been set for yet another record low Arctic sea ice extent late next summer.
    Of course those in denial and the contrarians, who feel it necessary to point out every flaw, perceived or real, will nitpick their way through this, as they always do. I guess it would be too much to request that we keep our critique constructive and try and focus on the much more important big picture here?
    A last point, if some of the wording may seem ‘strong’, like it or not that is what is needed to mobilize people. Many, many people have fallen victim to the rumours that the warming has stopped, slowed or even reversed the last 10 years. This has given people a false sense of security. That said, the policy makers and politicians do finally seem to be showing a sense of urgency (except Canada of course, my apologies to everyone on our behalf for showing no leadership at all on this file).

    PS: Why were Swanson et al. (2009) and Murphy et al. (2009) not included? They would have really strengthened the report.

  33. Chip Knappenberger:

    Bud (re#24),

    In fact, in my work (currently under peer-review), I do precisely as you describe that I should–not as you describe what you think I did. In my comment #6 I wrote that I am working “on trying to properly compare observed global temperature trends during the past 5-15 years with model projections during similarly short periods.” Note “properly” compare and during “similarly” short periods–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 employ a technique similar, but more widely applied and better constrained, than either Easterling and Wehner (GRL 2009) or Knight et al. (BAMS 2009) both of which also compared short-period observed trends with short period model projections. Since both were published in the literature, I assume that not everyone thinks the task pointless.

    -Chip

  34. Don S:

    sascha says:
    @ eric, regarding displacement caused by rise in sea level by 2100:

    Ever flown into Vancouver, BC? You’ll still be able to land at the Vancouver airport after 1 m of sea level rise …. if you have a seaplane.

    Well, coming from an engineering background, I must say that totally depends on how much the Vancouverians love there airport… (that is, how much they are willing to spend on constructional measures…)
    ——-
    The entire Schiphol Airport in Amsterdam is below sea level. The runways are 10′ or so below sea level. If there is sufficient financial incentive Vancouver will figure it out.

    [Response: That's the point. There are *costs* associated with global warming.--eric]

  35. SecularAnimist:

    sascha, regarding your comments (e.g. #7 and thereafter) about what you seem to feel is “alarmist” ambiguity & vagueness in the report’s assessment of potential sea level rise, here is what the Executive Summary has to say:

    Sea-level prediction revised: By 2100, global sea-level is likely to rise at least twice as much as projected by Working Group 1 of the IPCC AR4, for unmitigated emissions it may well exceed 1 meter. The upper limit has been estimated as – 2 meters sea-level rise by 2100. Sea-level will continue to rise for centuries after global temperature have been stabilized and several meters of sea level rise must be expected over the next few centuries.

    I think that language makes it very clear what time frames the report is talking about for “several meters” of sea level rise.

    Personally I am not too “alarmed” about sea level rise because by the time the Vancouver airport is under water, I expect that human civilization will have long since succumbed to world-wide famine resulting from a global failure of agriculture resulting from prolonged, intense, widespread continent-wide mega-droughts — not to mention the disappearance of fresh water supplies for billions of people.

  36. Chip Knappenberger:

    Chad (re# 27),

    Right, sorry, I misunderstood. Comparing observed trends over a particular calendar period with model projected trends during the same calendar period, during short timescales is not a robust comparison–too much weather noise.

    That’s why I do my comparisons using the complete distribution of trends derived from all similarly lengthed periods during the first 2 decades of the model projections for the 21st century–a period of relatively stationary projected change–and one that should be similar to recent observed years.

    -Chip

  37. GPB:

    “[Response: That's the point. There are *costs* associated with global warming.--eric]”

    But there are also benefits. Longer growing season, more arable land, and lower heating bills :-)

    [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]

  38. viento:

    Why is the paper by Siddal, Stocker and Clark published in Nature Geosciences 2009, which indicates a sea-level rise in the range of 7-82 cm, and therefore clearly different from Rahmstorf 2007, not even cited?

    [Response: For some perspective on that, see Stefan's discussion of that paper, here. -eric]

  39. Mark A. York:

    RE: 15, “Where? Please cite a reliable source.”

    Meet Jason-1 and Grace at your service.

    http://climate.nasa.gov/keyIndicators/

  40. dhogaza:

    I don’t know, maybe I did misinterpret the language a litte. I am indeed a non-native speaker (btw, I’m honoured you guessed it primarily from my name rather than from my writing) …

    You write just fine in my language, except for the english rather than american spelling :)

    Part of my personal prejudice may be negative experiences with statements publicized by overzealous environmental groups regarding global warming and similar topics – statements which I naturally believed at first – turning out to be really not much more than the most catastrophic-sounding paragraph of a reputable scientific publication quoted out of context…

    I don’t think anyone would deny that this happens at times …

  41. Edward Mazria:

    You can visually see what 1 to 2 meters of sea level rise would look like for hundreds of cities and towns along the east, west and gulf coast at: http://www.architecture2030.org/current_situation/cutting_edge.html

  42. JonJermey:

    “The entire Schiphol Airport in Amsterdam is below sea level. The runways are 10′ or so below sea level. If there is sufficient financial incentive Vancouver will figure it out.

    [Response: That's the point. There are *costs* associated with global warming.--eric]”

    Well, you have just changed your tack. First you say that it will be a disaster because of flooding; now you want to say that it will be a disaster because of the costs of flood mitigation. But cutting emissions also has costs: and it’s not at all clear to me — even assuming the sea-level rise data is more reliable than another data set has recently been shown to be — that the cost of building a 1m seawall is greater than the cost of cutting emissions. The first is a routine engineering operation that people do all the time and have been doing for centuries. The second requires a radical and drastic change in the way civilisation operates. If your reason for saying “We should do A rather than B.” is because B costs less, it’s not enough to merely assert that: you have to show it.

    [Response: Actually *I* don’t need to show anything. There is a huge literature on this already. Read it. You might start with the Stern report.

  43. Stuart:

    Can someone answer why CO2 is considered a pollutant? According to the graph at this link:
    http://www.barrettbellamyclimate.com/page24.htm
    which is formulated from the MODTRAN program, the widely proph­esied doubling in CO2 concentration from the pre-industrial value of 285 ppmv to 570 ppmv would be associated with an increase of just 1·5°C.
    This data takes into account the full path length of the atmosphere as well as broadening of the CO2 absorption bands.

    [Response: Those calculation were done "Keeping everything constant except for the CO2 concentration." They don't take into account the water vapor feedback (or any other feedbacks).--eric]

  44. Mark A. York:

    Lee Fu’s presentation on sea level at the JPL Climate Symposium is good. He also cites the Rahmstorf paper.

    http://climate.nasa.gov/ClimateSymposium/

    Up 20 cm (8 inches) since 1920.

  45. Llama Cheese:

    Bravo!
    This is excellently done! Seriously, whoever designed this is a freaking genius. Just in time to fight the denialists. Nobody can truly read this and walk away unconvinced of the need for action.

  46. Ryan O:

    This is for Eric Steig:

    I think you may have made an error in your response to #31. The cooling of the stratosphere is a transient, not equilibrium, condition. In the simplest example, let us assume solar output remains the same and neglect the any change in concentration of GHGs in the stratosphere.

    With these conditions, a stepwise increase in GHGs causes a temporary reduction in outgoing radiation through the stratosphere. As the stratosphere is warmed by both incoming solar radiation and outgoing re-radiation from the surface of the earth, the reduction in outgoing radiation results in stratospheric cooling.

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

    The reason the cooling stratosphere is an important characteristic of GHG warming is because GHG concentrations are continually rising (in contrast to the step change example) and, therefore, equilibrium is never reached. Even in this case, though, a cooling stratosphere does not necessarily follow for all conditions. Because stratospheric temperatures will eventually begin to recover as the troposphere approaches equilibrium, the stratosphere can warm even under conditions of increasing GHG concentrations if the rate of the GHG increase is reduced sufficiently.

  47. Timothy Chase:

    Mark A. York wrote in 39:

    RE: 15, “Where? Please cite a reliable source.”

    Meet Jason-1 and Grace at your service.

    http://climate.nasa.gov/keyIndicators/

    Mark, I had been wondering what was going on with the current El Nino. Your link provides the following when you look at the current sea-level data:

    November 12, 2009

    El Niño is experiencing a late-fall resurgence. Recent sea-level height data from the NASA/European Ocean Surface Topography Mission/Jason-2 oceanography satellite show that a large-scale, sustained weakening of trade winds in the western and central equatorial Pacific during October has triggered a strong, eastward-moving wave of warm water, known as a Kelvin wave. In the central and eastern equatorial Pacific, this warm wave appears as the large area of higher-than-normal sea surface heights (warmer-than-normal sea surface temperatures) between 170 degrees east and 100 degrees west longitude. A series of similar, weaker events that began in June 2009 initially triggered and has sustained the present El Niño condition.

    El Nino Picking Up Steam
    http://www.jpl.nasa.gov/news/features.cfm?feature=2358

    There are links to some great resources, e.g., satellite images and data from Jason, Grace, Terra, QuikSat, AIRS and MLS along the right hand side, at least some of which contain links to entire websites that are devoted to the specific satellites and the images and data obtained from them.

    Definitely worth bookmarking.

  48. Axel Edgren:

    @ Mark Gibb

    “My problems with the AGW community do not involve the slow, methodological plodding of good science, it is the alarmism that is desired by politicians so they have the cover they need to empower themselves.”

    Politicians! In general! They will kill us all!

    Nothing alarmist about your worries, Mark…

  49. Chris S.:

    #37 GPB

    Whilst growing season may be extended beyond the summer months into autumn, warmer, wetter, winters are likely to mean that spring sowing won’t get much earlier (as the ground will be too sodden). Crop pests and disease vectors however (e.g. aphids) show a strong relationship to winter temperature (particularly Jan-Feb) and are expected to arrive in crops (in higher numbers) at an earlier – more susceptible – growth stage.

  50. Hank Roberts:

    > *where* do you get the idea that there will be
    > more arable land?!)

    We’ve seen this error before:
    http://tamino.wordpress.com/2007/12/16/wiggles/#comment-10862

    See also ‘Mercator’ in this nonsense:
    canadafreepress.com/2006/harris061206.htm

  51. Tony O'Brien:

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

    This is still a fairly conservative projection.

  52. David Horton:

    “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?

  53. Bernie:

    #38
    Eric:
    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]

  54. PHG:

    Excellent summary.

    Personally, I thought the pictures were great as well.

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

  55. AlCrawford:

    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!

  56. blagan:

    RE: # 13 “Why not?”

    Chip
    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.

  57. David B. Benson:

    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. :-(

  58. calyptorhynchus:

    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?

  59. Jim Bullis, Miastrada Co.:

    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.

  60. Vinny Burgoo:

    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]

  61. Don Shor:

    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 http://www.sciencemag.org/cgi/content/abstract/1135456

    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.

  62. semiguy:

    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…

  63. Ike Solem:

    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:

    http://www.worldclimatereport.com/index.php/2009/11/10/airborne-fraction-of-human-co2-emissions-constant-over-time/

    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:

    http://www.sciencedaily.com/releases/2009/01/090122141222.htm

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

    http://www.sciencedaily.com/releases/2009/03/090305141625.htm

    “…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:
    http://arstechnica.com/science/news/2009/11/have-we-started-to-fill-our-carbon-sinks.ars

    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.

  64. Jere Krischel:

    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]

  65. SecularAnimist:

    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.

  66. Lennart van der Linde:

    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:
    http://www.envirosecurity.org/cctm/StateoftheDebate2.pdf

    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.

  67. Guy:

    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…)

  68. Spaceman Spiff:

    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’.

    http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/

    and

    http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument-part-ii/

    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.

  69. Hank Roberts:

    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 – agu.org
    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)

  70. Spaceman Spiff:

    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: http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.doc.html . Very instructive.

  71. Jim Bouldin:

    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?

  72. Andrew:

    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.

  73. Bill:

    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]

  74. Bill:

    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…).

  75. Joe Horvath:

    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.

  76. andy:

    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.

  77. Brad:

    Hi,

    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.

  78. Jere Krischel:

    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]

  79. dhogaza:

    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.

  80. Paul Schmold:

    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.

  81. Nicolas Nierenberg:

    Eric,

    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]

  82. Nicolas Nierenberg:

    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.

  83. Jere Krischel:

    [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?

  84. eric:

    Folks.

    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.

    Eric

  85. Ike Solem:

    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: http://www.cru.uea.ac.uk/cru/info/ukrainfall/

    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.”

  86. The Wonderer:

    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?

  87. Nicolas Nierenberg:

    Eric,

    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]

  88. Ike Solem:

    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.”

    http://www.guardian.co.uk/environment/2009/nov/22/green-technology-climate-change-g77

    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.

  89. Sloop:

    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.

  90. Icarus:

    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:

    http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf

    … 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)?

    Cheers!

  91. Hank Roberts:

    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.
    Answer: http://www.ucar.edu/learn/1_1_1.htm

  92. Edward Greisch:

    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:
    http://www.marklynas.org/2007/4/23/six-steps-to-hell-summary-of-six-degrees-as-published-in-the-guardian
    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.

    http://www.sciam.com/article.cfm?articleID=00037A5D-A938-150E-A93883414B7F0000&sc=I100322

    http://www.geosociety.org/meetings/2003/prPennStateKump.htm
    http://www.astrobio.net is a NASA web zine. See:

    http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=672

    http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=1535

    http://www.astrobio.net/news/article2509.html

    http://astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2429&mode=thread&order=0&thold=0

    “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.

  93. dfree:

    http://www.spaceref.com/news/viewpr.html?pid=15385

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

    I love this site

  94. The Wonderer:

    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.

  95. Nicolas Nierenberg:

    Can you please point out anything in section 10.3.3.1 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.

  96. Joel Shore:

    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.

  97. Patrick 027:

    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.

  98. Jere Krischel:

    [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]

  99. TD:

    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]

  100. oracle2world:

    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]

  101. Jordan L:

    Great summary of the key points in this most important report. I’m quite nervous, to say the least, about what will result in Copenhagen. I wish there was a way to effectively educate the public the dangers a few degrees in temperature pose to ice sheets, sea levels and many climate processes that are difficult to control and understand such as ocean currents and extreme weather patterns. While this sort of report is necessary, I wonder how effective these scientists are at getting the word out on these disturbing findings. If you interested I further express my own frustrations, specifically at the American government, in a column on my blog: http://www.songofsibyl.com/2009/11/23/the-road-to-copenhagen-global-warming-or-climate-change .

  102. TD:

    Neophyte Request:

    For some years I have been searching for an ACCESSABLE book that explains AGW. The books I have consulted rely way, way to heavily on argument from authority. “Smart people say this, so you are wise to believe it.” They rarely explain the underlying data and pros/cons of using this data set or that data set. I find the Cophenhagen Diagnosis suffering from the same problem (at least for a neophyte like me)

    If I could order a book its outline would be like:
    1.Remembering your high-school earth science – explaining the radiative balance and heat distribution throughout the world. The roles of clouds, currents, etc. etc.
    2.CO2’s role in that balance and its significance/magnitude against other factors. (The report today addresses this when it compares C02 vs soloar!!!!)
    3.Measuring temperature from Ancient times (the past 1000’s of years.) The insight and problems of using proxy data. It would list the proxies. It would list the pro’s and con’s of each proxy.
    4.Measuring temperature in modern times. Weather stations, satellite, others. Getting this temperature at the Earth’s surface, significant altitudes and land vs sea.
    5.Explanation of the various forecasts and the significant factors that explain their difference.

    No AGW book that I have ever seen does this. Instead, they throw up a bunch of graphs and quote a lot of studies and say “now, we must act.” This is an argument from authority. As such, it is unpersuasive.

    I have had my eye open for such a book but one has never found me, nor I it.

    Books not worth recommending to me:
    1. Al Gore’s various books. Too political, even if it is good science.
    2. M Mann’s Dire Predictions. Just throws up the usual graphs. Does not explain the underlying pro’s and con’s of proxy data, for example
    3. Gavin’s book… too much on pictures and forecast. (Full disclosure, I had asked this question to him.)

    [Response: I think George Philander’s book “Is the temperature rising” is quite good, and David Archers “Understanding the forecast” is even better. For a really full treatment though, you have to go back to physics texts on radiative transfer. Dennis Hartman’s book ‘Global PHysical Climatology” is also excellent. For a really complete start-to-finish yet quite accessible (if you can handle a few equations) is RC’s own Ray Pierrehumbert’s book– really excellent, I might add — that is in proof form on this web site, here

  103. TD:

    98 – Thanks… Just what I think I am looking for!

  104. William T:

    @ Mark Gibb – the obvious reason why protagonists on both sides of this debate end up resorting to ‘alarmist’ scenarios is that otherwise nothing would get done. People (and politicians) are only going to agree to massive inconvenience if there is a really serious threat. Face it, this has to be a political issue because it is politicians who will decide on the changes needed to respond to the scientific evidence. The impact of that evidence has to be spelled out in terms of ‘alarming’ dangers in order to stir the politicians into action. (and of course on the other side, the downsides of action have to be made very ‘alarming’ in order to stir up opposition).

    Otherwise it is merely yawn-inducing scientific arguing points that most people will care nothing about.

  105. Bud:

    @TD 102: as another “neophyte” I’ve started working my way (slowly, I’m a final year student so swamped enough already!) through Ray’s book, and I can fully recommend it.

    Eric, I honestly sympathise with that crap you just had to put up with from oracle2world. I’d leave that up as an example of why moderation on some blogs is needed. I come here to learn from experts (both above and below the line) and to see a reasonable subset of critical comments from those outside the consensus. Not to read pages and pages of that nonsense. That kind of post is why few people bother to argue at the Guardian blog anymore.

  106. Patrick 027:

    Clarification
    Re 97 myself (Re 46 Ryan O) -
    “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?),”

    Actually, my impression has been that the tropopause level itself will be higher and colder at new GHG-forced-warming equilibrium, so …

    (Specific results may vary based on spectra and concentration variations (water vapor, ozone) of gases, and of course, cloud feedbacks, etc.)

  107. Journeyman:

    Ike Solem, regarding daily high low temperature records, I would not expect the number of these record to be same, when I know the average current temperatures are higher than at the start of my instrumental record period. Given 100 years of lower temperatures, I would be shocked at the number of low records being found. If temperatures stayed in equilibrium after 100 years of warming, what ratio of highs to lows would you expect to find?

  108. Journeyman:

    How is this different from the Copenhagen Synthesis Report?

  109. wayne davidson:

    I am sure all GC models are geared up better since the 80′s, but El-Nino not flaring up like in 1997-98 with the same strength fascinates, and I wonder if there is a plausible explanation of its relative quiesence. Which is useful, since despite a weaker El-Nino than 1997 GT’s are warmer… There is some sort of synergistic convergence which creates strong El_Ninos, much a do with natural variability, would be nice to know what triggers a massive event. Surely 1997-1998 el-nino will be surpassed one year, but , in other words, what is stopping it from happening again?

  110. Martin Vermeer:

    Nicolas Nierenberg #81, #87, #95:

    I read what you wrote and it looks generally OK, but one problem. Yes, cross-validation as done is a good way to find out if a relationship found is real, and how good it is, but note that in this case, the relationship is tested using only half of the data points. This means that you may not transfer back the conclusions unchanged to the fit based on all data points.

    If you do a linear regression, and then remove half of your data points, everything else unchanged, the standard error of your slope goes up by sqrt(2). If additionally, you shrink the span of values for the temperatures T and sea level rise rates dH/dt also by a factor of roughly 2, that adds a further 2x to the slope uncertainty. Totalling 2*sqrt(2) = 2.8x.

    Now let’s take your values 0.42 and 0.24 for the slope estimates from the two halves. Express it as 0.33 +/- 0.09. To carry over the uncertainty to the full data fit, you must divide by 2.8, yielding 0.33 +/- 0.03. 10% relative uncertainty. This is one-sigma only; climatologists seem to always want to see two-sigma, or 5%-95% bounds…

    Yes, the half-data fits are very uncertain and sensitive to small changes in method. This is not surprising: consider that 15-year smoothing was applied, so the number of independent data points in them cannot be more than 4, likely less, considering autocorrelation. And from that, you try to estimate two parameters. No surprise really.

    Unrelatedly, one problem with R07 that no critic seems to have hooked onto is, that it uses the language of hypothesis testing when it is actually doing nothing of the kind. Everybody seems to do that: the commenters on R07; even the IPCC, causing much head-scratching (google “silly nulls”; “the greenhouse effect doesn’t exist” is no less silly than “temperature doesn’t affect sea level”). Scientists doing what they learned in school and know how to :-)

  111. isotopious:

    Figure 21, page 52.

    This is probably the worst figure I have ever seen. Look at the units!
    All the degrees centigrade are making me dizzy.

    :/

  112. Terry:

    Eric…Thanks for your time on here. I understand atmospheric physics and the models pretty well, but I struggle with the concept of Antarctic Ice loss. I do understand WAIS loss by calving at the sea/ice interface if the sea temp is high enuf, but glacial loss has me stumped when it is below zero, unless is is mechanical due to a loss of ice at the sea interface. If you could point me to a robust backgrounder that includes the thermodynamics and correlations of sea/air temps with ice loss, I would be vey grateful. Many thanks

    [Response: First off, don't confuse land ice and sea ice (I'm not saying you are, but I can't quite tell as you've not being specific). I assume we are talking about land ice here. Second, the calving is all mechanical. Water temperature doesn't matter (it's always right about at freezing at the ice margin!). There are plenty good references on all this, but a great place to start is probably with The Physics Of Glaciers (Stan Paterson), readily found on Amazon or whatever. Hope that helps --eric]

  113. Ben:

    Is it too much to ask for an html version with links to references and references hyperlinked to original articles or abstracts online? Peer-reviewed journals do that, why can’t you? And it’s not too hard to get hyperlinks in pdf. This report looks like an advertising brochure.

    [Response:Journals have staff and budgets to pay them for this sort of thing. We're working in our spare time. If you'd like to do the work for us, we'll gladly upload the finished project to the website.--eric]

  114. HR:

    Anybody answering questions on the ‘science’ in this document? Because I have one.

    In the CO2 section it’s states that the rate of production of human CO2 has increased since 1990. It also says that the amount of CO2 absorbed by the natural sinks has fallen (by 5%). When you look at the graph that shows CO2 in the atmosphere in ppm you see a linear increase in this for the past 50 years.

    My question is if the first two points are correct you would expect to see CO2 accumulating in the atmosphere at a faster rate in recent times but the linear nature of the ppm graph suggests a steady rate of increase over 50 years. What am I misunderstanding here?

  115. Guy:

    Eric – would be grateful if you could comment on #69, even though #84. My post in #69 comes right out of the report itself – some further detailed comment on context would undoubtedly help how this report is perceived by the public. Communication of science to the public is the raison d’etre for RC, isn’t it?

    So can the public objectively rely on the report’s conclusions as being a completely representative cross section of the climate science academic community, or is it a subset? I can’t think of a more important, or timely question to answer, and the lack of one does great harm imho.

    [Response: Are the report's conclusions " a completely representative cross section of the climate science academic community"? Probably not. This report didn't go through the same level of review as did IPCC. Did we do our level best to make it representative? Yes. Why should you trust what I'm saying? Well, you don't have to. You could go ask any of the other others (all 23 of them) who are *not* part of RealClimate. Or you could ask various people who are not even on the author list. Take a sample, see what you come up with. No doubt you will find people who will quibble with some details, but for the overall picture, and the major conclusions....I think the results of such a survey will restore your confidence.--eric]

  116. Didactylos:

    HR (#114):
    The rate of increase is much easier to see if you look at a longer timescale. The report only shows 30 years (I would guess for consistency with the CH4 graph). Tamino has an excellent discussion of this, with his usual statistical analysis: CO2 Acceleration. He calculates that the acceleration is is about 0.025 ppm/yr/yr.

  117. Anne van der Bom:

    Mark Gibb,
    24 November 2009 at 2:08 PM

    You seem to have made up your mind firmly before reading the report. Why waste time reading it?

  118. viento:

    Why is the review paper by Milne et al, Nature Geoscience 2009, which also disagrees with Rahmstorf 2007, not even cited?

    [Response:That paper is an assessment of the causes of sea level change, not a paper on projections. And it doesn't disagree with Rahmstorf. They say "We find that most studies constrain global mean sea-level rise to less than one metre over the twenty-first century..." and "For example, a recent study concluded on a sea-level rise of 30–80 cm by 2100 in northwest Europe. It is possible that in specific areas, the upper bound could be significantly higher..." Both these statements are in complete agreement with the mean (<1 m) and high end (>1m, but < < 2m) of Rahmstorf (2007) and the several others studies we cite.--eric]

  119. greg kai:

    Where is the “benefits” section in their cost/benefits analysis of future warming consequences? Or is there really no benefits involved? This means that we live (lived?) in the best of all possible worlds regarding temperature, sea level and other global environmental conditions??? I am glad that the report authors are so fond of Leibnitz…

    Seriously, there is no cost/benefits analysis analysis, it is exclusively an analysis of risks linked to projected temperatures. It is of course ok to do that, but I do not believe that it makes a correct summary for decision makers, as it, by definintion, paint a one-sided picture.

    My other gripe with the report is that it simplify the solar forcing to the single issue of global energy flux from the sun and it’s (very slight) variation. The hypothesis from the solar camp consider other parameters (spectrum, magnetic field variations), whose influence is much less direct (and hence much less clear), but on the other hand have much more variation accross solar cycles…

    [Response:Regarding risk analysis, I refer you to IPCC Working Groups 2 and 3, neither of which we claim to be updating here. And you might look at e.g. Battisti and Naylor in Science if you want to consider risks. As for the arguments made by the 'solar camp', they have not been convincing at all, as we have discussed at length. The evidence *against* the solar component being a major player is overwhelming. We do not claim that the Copenhagen Diagnosis is a comprehensive summary of all possible arguments 'for' or 'against'. It is a summary of major new and convincing data. There has been nothing new or convincing from the solar camp.--eric]

  120. gbettanini:

    Sorry but i can’t well understand the figure #16 about the sea level rise.
    The interpolation of the satellite observed rise indicates a level increase of about 35 cm every 100 years. The highest prediction of the rise from IPCC is around 60 cm every 100 years. So i think that the ‘IPCC Predictions’ zone must be higher than the zone displayed in figure #16.

  121. Barton Paul Levenson:

    Chip: If models were getting things right (including weather noise), then the observed trends would be contained by the models at all time frames.

    BPL: Your “then” is a non sequitur. You’re confusing climate with weather.

    Chip: That they are not, is a robust result that the models (or at least some of them) aren’t working right.

    BPL: Wrong again. The models give projections for climate, not weather.

  122. Stuart:

    Thanks for your response to comment #43:
    “Those calculation were done “Keeping everything constant except for the CO2 concentration.” They don’t take into account the water vapor feedback (or any other feedbacks).–eric”

    But isn’t it true that feedback is not understood and cannot be measured directly? I’m a non-climate scientist (originally an infrared spectroscopist) – I’m trying to get a handle on what all the assumptions are that have been made in inferring the predicted changes.

    See recent essay here by Roy Spencer:
    http://www.barrettbellamyclimate.com/page25.htm
    Despite the fact that the magnitude of anthropogenic global warming depends mostly upon the strengths of feedbacks in the climate system, there is no known way to actually measure those feedbacks from observational data.

    The IPCC has admitted as much on p. 640 of the IPCC AR4 report, at the end of section 8.6, which is entitled “Climate Sensitivity and Feedbacks”:

    “A number of diagnostic tests have been proposed…but few of them have been applied to a majority of the models currently in use. Moreover, it is not yet clear which tests are critical for constraining future projections (of warming). Consequently, a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed.”…….
    And until such a test is devised, the warming estimates produced by the IPCC’s twenty-something climate models are little more than educated guesses.

    [Response: There are a number of papers which address the issues you bring up. For example, "Knutti, R. and Hegerl, G. C. [2008]
    The equilibrium sensitivity of the earth’s temperature to radiation changes Nature Geoscience ; 1 ; 735-743 “–eric]

  123. Barton Paul Levenson:

    Jim Bullis: You can’t be serious that pV=nRT applies after millions of years of adjusting.

    BPL: Huh? What? Come again?

    Why would the ideal gas law stop working?

  124. Barton Paul Levenson:

    Jere Krischel: What evidence do you have that a warmer world is worse for people,

    BPL: The fraction of Earth’s land surface “severely dry” by the Palmer Drought Severity Index was 12% in 1970. By 2002 that figure was 30%. Ask the Australians about global-warming-induced drought.

    Ref: Dai, A., K.E. Trenberth, and T. Qian 2004. “A Global Dataset of Palmer Drought Severity Index for 1870–2002: Relationship with Soil Moisture and Effects of Surface Warming.” J. Hydrometeorol. 1, 1117-1130.

    A billion people in Asia and Latin America depend on glacier melt for fresh water. The glaciers are receding fast. India and Pakistan have already exchanged fire and had troops killed over which side owns a glacier.

    JK: especially since we’ve already had that in the medieval warm period?

    BPL: No, we have not. The MWP was cooler than now:

    Bradley, R.S., Hughes, M.K., and H.F. Diaz 2003. “Climate Change in Medieval Time.” Science 302, 404-405.

    Goosse H., Arzel O., Luterbacher J., Mann M.E., Renssen H., Riedwyl N., Timmermann A., Xoplaki E., Wanner H. 2006. “The Origin of the European ‘Medieval Warm Period’.” Clim. Past, 2, 99–113.

    Osborn, Timothy J. and Keith R. Briffa 2006. “The Spatial Extent of 20th-Century Warmth in the Context of the Past 1200 Years.” Science 311, 841-844.

  125. Barton Paul Levenson:

    dfree: 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.”

    BPL: Try here:

    Revelle, R. and H.E. Suess 1957. “Carbon Dioxide Exchange between Atmosphere and Ocean and the Question of an Increase of Atmospheric CO2 During the Past Decades.” Tellus 9, 18-27.

    Suess, H.E. 1955. “Radiocarbon Concentration in Modern Wood.” Sci. 122, 415-417.

    dfree: ..events 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!..my 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?

    BPL: Try here:

    http://www.grist.org/article/volcanoes-emit-more-co2-than-humans/

  126. NeilT:

    It is claimed that this report is alarmist, that the tone and tenor of the report overstates the case and that the impacts of Global Warming will be much more benign than stated in the report.

    I see the short version as this. This report summary says nothing about storm intensity, surges or impact of even moderate storms in a world where sea levels are changed by warming. It does state that storms are getting worse, but that is only part of the picture. It says nothing about the sea defences which will be overwhelmed and people constantly talk about a 1M sea level rise as if it is static.

    Looking at the royal society report on the 1953 East Coast flooding in England and the Netherlands

    http://rsta.royalsocietypublishing.org/content/363/1831/1293.full

    and the comments about the lack of calculation of sea level rise in the sea defence design, it is guaranteed that it will not take hurricanes or typhoons to inundate the land and kill people in 50 years time. It will simply take a 50 or 100 year storm. Which, if we are to believe the predictions, will be much more frequent.

    The report could have, quite easily, stated that displacement from storms would become more frequent and that significant portions of arable land would be lost to saltwater contamination for periods of years; damaging the food supply.

    Given that 100 year storms will come around every 70 years (or less), and it will only take 30 or 50 year storms to do the same damage as 200 year storms; with the sea level rises, I think the report is actually understating the impact of Global Warming and sea level rise by quite a large degree.

    And that is without the demographics of people moving to coastal regions with at risk areas seeing 30-90% increases in population increase based upon the “security” of these se defences.

    When we it starts to hurt, we won’t have 25 or 30 years to engineer solutions. We will have months. The best defence is not to go there in the first place.

  127. jean claude:

    It’s okay to admit that there are some things we don’t know. That at our current level of understanding, some systems are beyond our complexity horizon.

    This does not mean that what we think we know is wrong. It also does not mean that what we think we know is right.

    Some variables are well defined, some are poorly defined and others are either ignored or unknown. The result of any honest AGW model is a very low degree of confidence. Degrees of confidence can not even be honestly calculated because of all of the unknowns and poorly understood variables.

    This is where the real dispute lies within the scientific community: Do we include all variables, those known and well understood; those that are moderately or poorly known; and those that remain unknown except in the sketchiest of details?

    If you deal only with those variables that are well known you can make predictions with what seems like a high degree of confidence, but how reflective are they of the actual system as it exists within nature?

    Any theory at this level of development can show promise in shedding light on the direction of future research. What it cannot do nor should not do is use such a poorly understood complex system as a platform to pontificate on public policies that will affect billions of lives and trillions of dollars.

  128. Dale:

    This may be deleted but I know from my upbringing among denialist types (My father was a McCarthy apologist) that their reality is not based on facts but rather on factoids. They have about as much affinity to science as Little Abner has to Harvard. What they believe is unfettered capitalism is a pure and clean as the fresh driven snow and that any inconvenient truth no matter how compelling will never be accepted.

    I really appreciate what Gavin, you and others have to deal with. I see a mob mentality out there among the anti AGW crowd (To be honest there are a few with the ability to give and take but not many) and they remind me of the mob going off half cocked that drove Ryan White, the young AIDS victim from his school in Kokomo, Indiana in the 80′s.

  129. Richard Steckis:

    Eric says:

    “Response: That’s the point. There are *costs* associated with global warming.–eric”

    There are both costs and benefits associated with any climate change whether man induced or not. That is the nature of changing ecosystems.

    You are anthropomorphising.

  130. Cedric Knight:

    The “Copenhagen Diagnosis” looks to me, a lay reader, to be a very well-produced and comprehensible update. I hope it receives a very wide distribution in the next few weeks.

    One thing confused me on p38. “The CO2 content of the oceans.. continues to increase by about 2 Gt per year (Sabine et al, 2004)” I’ve been quoting to people that CO2 (not carbon) emissions are about 26 Gt per year, and that up to a third of emitted CO2 is currently able to be absorbed by the oceans… which would be more than 8 Gt pa. Does this perhaps mean 2 Gt carbon rather than CO2? (And should we standardise on using carbon, CO2, or CO2e?) Alternatively, is the 2 Gt a net balance because some dissolved CO2 precipitates into insoluble carbonates or is taken out of solution by biological calcification?

  131. Ray Ladbury:

    HR, Do a Taylor expansion of exp(t/t0). Now make delta t/t0 very small, and the linear term dominates. That does not, however, negate the fact that the increase is exponential. Likewise, look at interest on your CD. Over short times, the returns look constant. Only over longer terms does the compounding kick in. Make sense now?

  132. Ray Ladbury:

    Isotopious @111

    Yeah, math is scary, huh!

  133. Alan Millar:

    The whole basis of the cause of some of the observations described in the Copenhagen paper is completely unresolved at this time in my opinion.

    One of the most interesting of the leaked e-mails is, to my eyes, the one which iincludes reference to the 1910 – 1940 ‘problem’.

    “It would be good to remove at least part of the 1940s blip,
    but we are still left with “why the blip”.

    Let me go further. If you look at NH vs SH and the aerosol
    effect (qualitatively or with MAGICC) then with a reduced
    ocean blip we get continuous warming in the SH, and a cooling
    in the NH — just as one would expect with mainly NH aerosols.

    The other interesting thing is (as Foukal et al. note — from
    MAGICC) that the 1910-40 warming cannot be solar. The Sun can
    get at most 10% of this with Wang et al solar, less with Foukal
    solar. So this may well be NADW, as Sarah and I noted in 1987
    (and also Schlesinger later). A reduced SST blip in the 1940s
    makes the 1910-40 warming larger than the SH (which it
    currently is not) — but not really enough.

    So … why was the SH so cold around 1910? Another SST problem?
    (SH/NH data also attached.)”

    This 1910-1940 issue goes to the heart of what level of confidence we can have in the AGW theory and the associated GCMs.

    Upto now it seems that certain AGW scientists and advocates have been happy to wave their hands a bit whilst muttering Solar and Aerosols as the answer as to why global temperatures increased at a similar rate during this period as compared to the latter part of the century, with little help from increasing CO2 levels.

    I have known all along that this is rubbish. If you believe in AGW then you can only allow a small fraction of the observed increase in temperatures to be attributable to increased solar activity. As far as aerosols go this is a direct lie. Aerosols increased very sharply during this time. This is a fact confirmed by the Greenland ice cores.

    Now we can see, in writing, that this problem is unresolved by scientists at the heart of the AGW hypothesis and they do no believe the meme they have happily allowed to become established as the answer to this ‘problem’.

    So we know for certain that we have a situation where an unknown combination of climatic factors caused the global temperatures to rise at a significant rate comparable to the late 20th century and this remains unresolved.

    I am sure that most people here can see what this means for the AGW hypothesis. Logic dictates that if you cannot explain one rise over a similar period then you cannot explain another rise over a similar period. Unless you can identify and isolate the significant factors in the earlier period then you cannot know whether these unknown factors are driving the rise in the latter period, it is unarguable logic.

    This disconnect has been hidden in my view. It needs to be addressed and made known and highlighted in all discussions with policy makers etc. Willful failure to do so would be similar to sticking fingers in your ears and going “La La La……”!

    I would appreciate someone at RC addressing this issue and justify pushing ahead with very costly change to society whilst this huge issue lies unresoved at the heart of the AGW hypothesis.

    Please don’t give the glib answer that ‘Just because we don’t know everything, doesn’t mean that we know nothing’ Can there be a more fatuous and vacuous statement when it comes to science?

    Is there any other area of science that would give a free pass to a theory that had huge uncertainties, unresolved crucial issues and downright conflicts in emperical observations at the centre of the arguement just by using the phrase ‘Just because…….’?

    Alan

  134. Paul UK:

    Re: comment 8: sascha

    Sascha. I live near a city that is at risk of flooding, Portsmouth, Hampshire, England. Most of it is barely 5 metres above sea level and many parts are barely a metre or two above sea level. I recently took the bus down to Gun Wharf Quays and noticed the high tide mark around the bottom of the Millenium tower. Then I noticed that where I was standing was barely 1.5 metres above the high tide mark.
    This development was finished a few years ago. It’s going to be flooded (along with the posh quay side shops) in a few decades, does that make sense to you?

    Maybe in the time scales that consumerism is based on, then anything beyond a decade or two is a long time. But we can’t think like that any more.
    Portsmouth has a population of 200,000. Where I live it is a problem finding land to build 2000 homes let alone tens of thousands. We are already building on farmland here, rehousing Portsmouths population is going to be horrendous and I doubt any suitable sea defence will work.

  135. tharanga:

    Is my eye playing tricks on me, or did somebody misspell Pielke as Piekle on p21, and the reference list?

  136. tharanga:

    Regarding Antarctica, “Antarctica is not cooling: it has warmed overall over at least the past 50 years.”

    I haven’t read your paper yet (Steig et al), but referring to the figures here, http://www.realclimate.org/index.php/archives/2009/01/state-of-antarctica-red-or-blue/ , one can see cooling in East Antarctica in the time period of the ozone hole (as the report also mentions, but doesn’t show graphically). In the period since 1969, what is the trend for the entire continent? To my eye, it looks like the warming in West Antarctica and the Peninsula outweigh the cooling over the larger area of East Antarctica, but spatial averaging by eyeball isn’t very robust.

  137. Ike Solem:

    Climate science update: from bad to worse

    by Staff Writers
    Paris (AFP) Nov 24, 2009
    “The planet could warm by seven degrees Celsius (10.8 degrees Fahrenheit) and sea levels could rise by more than a metre (3.25 feet) by 2100, scenarios that just two years ago were viewed as improbable, scientists said on Tuesday.”

    “In the widest overview on global warming since a landmark report by the UN Intergovernmental Panel on Climate Change (IPCC) report in 2007, the authors said manoeuvering room for tackling the carbon crisis was now almost exhausted.”

    A search of the NY times reveals no coverage of that story, just more articles on the “sinister emails” – and no condemnation or discussion of the sinister breach of security, or why they sat on the story for over a month before running it right before Copenhagen. You would think they would be embarrassed – maybe not being fired is a more important consideration – just look at what happened to CNN’s entire science & tech news team when they started running reports on global warming? Fired within six months.

    A search of the BBC reveal no coverage of that story either, just more on the climate emails – and an effort to respin their severe flooding as completely unrelated to climate change:

    No, this seems to be much closer to what insurance brokers sometimes call “an act of God”. Forgive my imperial education, but more than a foot of rain fell in Seathwaite Farm in just 24 hours!

    An Act of God? I think there’s a good argument that dumping billions of tons of fossil fuel CO2 into the atmosphere for over a century is responsible – and Britain has always been a world leader in fossil fuel development, so it’s hard to claim that it wasn’t something that they themselves had a big hand in, unwittingly enough.

    What the BBC neglects to report is that Britain had similar floods two years ago – and as now, the government declared them to be a “once in a lifetime event.” Once in a lifetime? Once in a thousand years? A 500-year flood?

    London’s Financial Times had an interesting interview with some climate scientists:
    http://www.ft.com/cms/s/2/f1d9f856-d4ad-11de-a935-00144feabdc0.html

    “He believes that changes in rainfall patterns will have the most direct impact on people’s lives. In simple terms, he says, “the wet places will get wetter and the dry drier”. In the Mediterranean – one of the easiest regions to model – a 3°C temperature rise would cut rainfall by 20 per cent.”

    Compare that to British tabloids, which are printing glop like this:

    “Much more likely is that these floods and droughts are caused by old-fashioned, run-of-the-mill climate change of just the kind that occurs no matter how many cheap flights we take or how little we recycle.”

    Yes things just happen – why? Divine influence – yes, it is mysterious. Sacrifice a goat and pray for the rain to end, that’s my advice.

  138. pete:

    “[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]”

    Are you saying the Arctic sea ice is not subject to winds? If you honestly believe that, how can you explain the behavior of the ARCTIC sea ice the last 4 years. Going down to an historic (since 1973 satellite age, any other conclusion has absolutely no merit or evidence to the contrary) minimum, and now a scant two years later, the minimum extent has increased by well over 1 million km2.

    From NASA’s own website you get this quote……Nghiem said the rapid decline in winter perennial ice the past two years was caused by unusual winds. “Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic,” he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.
    http://www.nasa.gov/vision/earth/lookingatearth/quikscat-20071001.html

    [edit]

    Please cite some literature which contradicts the quote from NASA above and this quote which seemingly explains the ‘histroic’ loss of Arctic sea ice this century….”"The winds causing this trend in ice reduction were set up by an unusual pattern of atmospheric pressure that began at the beginning of this century,” Nghiem said.

    [Response: Sigh.. I never said Arctic sea ice isn't affected by winds. What I said was the Arctic sea ice is expected to be more predictable than Antarctic sea ice. The question was about Antarctic sea ice. Read the report, it is very clear on the Antarctic sea. If you still have questions *after* you have read it, I am happy to try to answer them. Accusations of my 'not telling the truth' are not, by the way, appreciated.--Eric]

  139. Thomas:

    At first I thought it was pretty good and compelling. But having slept on it I think there are some things missing.

    (1) The treatment of the way GHG cause warming was too simplistic (although a marvelous mental device to aid understanding). The obvious problem is that GHGes don’t operate as grey absorbers, so in some frequencies an IR photon emitted at the ground has a high probablity of directly escaping to space, while another whose frequency matches a strong absorption line will travel only a short distance. This observation combined with the line shape gives the logarithmic dependence on concentration…

    (2) GHGes other than CO2, and methane were barely mentioned. The fact that some novel (to the atmosphere) compound whose absorption bands/lines lie within the atmospheric windows can produce a hugely disproportionate forcing is important to understand. Clearly some of these industrial chemicals provide an important point of leverage for modifying the total anthropogenic forcing. Of course it needs to be emphasized that controlling the other GHGes alone will not prevent severe climate change. But ignoring them will lead to even greater anthropogenic forcings.

    Of course, some sort of balance between full detailed understanding and simplicity must be made to serve the wide audience for which this document is intended. I just think a few more details for the more technically inclined readers might have been in order.

  140. JBL:

    @Eric: your response in this post (currently #23) is all kinds of garbled — what were the parts that got cut off?

    [Response: Fixed.]

  141. mauri pelto:

    Ice loss when the temperature is below zero is dominated by the aforementioned calving which is easily observable, and the less observable and quantified basal melt by ocean water under the ice shelf. Under some ice shelves there is refreezing as well. Melt rates have commonly been observed to be over 10 meters per year.
    http://www.springerlink.com/content/065150756752463h/
    http://glacierchange.wordpress.com/2009/11/12/pine-island-glacier-grounding-line/
    http://journals.cambridge.org/download.php?file=/ANS/ANS16_03/S0954102004002068a.pdf&code=ddd0e8e8385d0666a8274c4fdfabca59

  142. mike roddy:

    This is a great report, especially the data graphs, and it should be sent to every news outlet and public school in the country. It’s clear, decisive, and urgently needed.

    My main quibble is the same one I often bring up: “Deforestation” should not be preceded with “Tropical”. Boreal and even US forest sinks sequester more carbon per acre, and are leveled just as relentlessly as in the tropics. Tree farm replacements are inadequate in terms of recovering soil and other biota, and are already showing poor survival compared to mature forests in terms of fire and pests.

    The reason scientists overlook this is that the US and Canada still have net forest CO2 sequestration due to their great size. This is already changing in British Columbia, and will soon change in the Rockies. In any case, net sequestration could be far higher if we slowed our profligate wood consumption and began to use truly sustainable foresty practices.

  143. pascal:

    Hi Eric

    I think there is an error in the scale unity of the fig9
    (The Greenland melt area).
    It is not 10^6 km2, but 10^5km2.

  144. Chris Dudley:

    I feel that the report does not cover adequately indications in the fossil record that sea level rise can occur very rapidly so that the 2 meter upper limit for 2100 may be spurious. http://www.nature.com/nature/journal/v458/n7240/edsumm/e090416-08.html AR4 did a better job of caveatting on this issue though there is was still too weak. Suggestion that mass loss in the East Antarctic Ice Sheet is accelerating by Chen et al. this week underscores that an upper bound for sea level rise this century is very hard to set.

  145. doug bennion:

    Gavin this is germane to the properties of pop-up window itself, not the topic being discussed. When I follow a link, the window does not resize to fit the new link, and I cannot resize it myself, so have to scroll up and down and side to side. It’s just a mild irritant, and maybe nothing you can do about it, but sizeable would rock. Thanks.

  146. eric:

    Comments are now turned off. Unfortunately, the comments are now running about 10:1 insults and innuendo. Serious discussion seems to have largely died off. The last couple of posters did raise some reasonable questions, and I will respond to them after Thanksgiving. Meanwhile happy Thanksgiving to all the American readers (and to everyone else, for that matter).–Eric