Exciting new concepts in earth systems science are emerging from the fertile intellect of one of Hot Topic’s most diligent readers, Ian Wishart. Either that, or he’s demonstrated (again) that he doesn’t understand what he’s writing about. In this astonishing post, published yesterday, he considers something he calls the “feedback warming effect”, and attempts to use a new paper on carbon cycle feedbacks to support Monckton’s nonsense on climate sensitivity.
Just as Chicken Little pontificates about the minutiae of a Monckton allegation about warming amplification being overestimated by six of seven times, along comes a new study in Nature that compared real data with the computer models and found CO2’s feedback warming effect has been exaggerated in the models by five or six times.
Monckton’s TV lies are not mentioned — minutiae to Wishart, obviously — but he then points to this paper: Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate, Frank et al, Nature, 2010; 463 (7280) as if it offers support for Monckton. It doesn’t, as I shall explain, but is Wishart wrong about Monckton, wrong about Frank et al, or both?
Monckton’s “paper”, Climate Sensitivity Reconsidered, is about what it says it is — the global temperature response to (by definition) a doubling of CO2 in the atmosphere. Monckton tries, and fails, to show that this response is small — he claims under 1ºC at doubling. Wishart refers to climate sensitivity as “warming amplification”, which — to be charitable — is a terminological inexactitude.
Frank et al, on the other hand, is the latest effort to pin down how much extra CO2 will be released from the various parts of the carbon cycle as global temperature increases, and suggests that it could be smaller than had been expected [Science Daily]. This “extra” CO2 clearly is an amplification of warming caused by human emissions, and it’s good news that this may be smaller than expected. Wishart describes the study thus:
…[it] compared real data with the computer models and found CO2’s feedback warming effect has been exaggerated in the models by five or six times.
What did Frank et al actually do? Physics World describes their method:
… David Frank and colleagues at the Swiss Federal Research Institute in Birmensdorf, the University of Bern and the Gutenberg University in Mainz have performed the most comprehensive analysis of carbon dioxide and temperature data yet. The team studied the period 1050–1800 AD, when manmade emissions were small enough to be ignored. Carbon dioxide levels were determined from three Antarctic ice cores. Average temperatures in the northern hemisphere were derived from nine different “proxy reconstructions” of temperature – average temperatures derived mostly from tree rings and the isotopic content of ice cores.
No comparisons with models, but a lot of use of paleoclimate data — you know, the tree ring stuff you find in those “debunked” hockeystick blades — and ice cores (and in Wishart-world they can’t be trusted, because Wishart relies on the “work” of EG Beck). Frank and his co-workers use this data to try to work out how much extra CO2 is released when the planet warms — and find that instead of the 40 ppmv/ºC found in previous empirical studies, it was more likely to be in the range 2–21 ppmv/°C, with 8 ppmv/°C being the most likely. The BBC asked Frank what this means for model projections of temperature change this century:
He said that if the results his paper were widely accepted, the overall effect on climate projections would be neutral.
“It might lead to a downward mean revision of those (climate) models which already include the carbon cycle, but an upward revision in those which do not include the carbon cycle.
“That’ll probably even itself out to signify no real change in the temperature projections overall,” he said.
Wishart doesn’t seem to have much of a handle on carbon cycle feedbacks and what they mean for model projections, but he’s canny enough to spot that someone might quibble with his penetrating analysis, so he includes this caveat:
A note for the pedants: the Monckton claim and the Nature paper are approaching a similar problem (magnitude of feedback warming) from slightly different directions (Monckton’s comment relates to rise in temp caused by doubling of CO2, whilst the Nature paper examines the increase in CO2 caused by a rise in temperature), but the general thrust of the arguments is similar: extra carbon dioxide is not going to cause as much feedback as previously claimed.
Clear as mud, Ian. This pedant would point out that the problems being considered are not the same and the “general thrust of the arguments” is not at all similar. Monckton isn’t talking about “feedback warming”, he’s talking about warming caused by a fixed increase (by definition a doubling over pre-industrial conditions) in CO2. He wants us to believe that the temperature response to increasing CO2 is tiny. On the other hand, Frank et al’s conclusions are based on linking small changes in global temperature over the period from 1050 to 1800 to small increases and decreases in CO2 levels.
In other words, if Monckton is right, then Frank et al’s methodology can’t work. Far from supporting Monckton, Frank et al add yet more reasons why he has to be wrong. Meanwhile, Wishart is wrong on all counts. I wonder how such an expert climate commentator could have failed to notice? Perhaps he should get his stuff peer reviewed. Where’s Monckton when you need him…?
Well Gareth you may be right, and you may have scored a small point against your beloved cranks. Then again you may be wrong…
And of course, then again, it probably won’t matter a toss, not if this commentator is to be believed…
“The swing of power to the BASIC group of countries (Brazil, South Africa, India, China) had likewise been signified for some time, but, again, it came with precipitate ease, leaving even the American President, Barack Obama, with no doubts as to where the political agenda on climate change was now heading, namely to the developing world, but especially to the East, and to the Pacific Rim. The dirigiste tropes of ‘Old Europe’, with its love of meaningless targets and carbon capping, will no longer carry weight, while Obama himself has been straitjacketed by the voters of Massachusetts, by the rust-belt Democrats, by a truculent Congress, by an increasingly-sceptical and disillusioned American public, but, above all, by the financial crisis. Nothing will now be effected that for a single moment curbs economic development, from China to Connecticut, from Africa to Alaska…”
http://web.me.com/sinfonia1/Clamour_Of_The_Times/Clamour_Of_The_Times/Entries/2010/1/30_Global_Warming%3A_the_Collapse_of_a_Grand_Narrative.html
Unfettered economic growth from the powerhouse of the developing world… Surely now Gareth that is the big issue. This academic debate re AGW seems passe and irrelevant now that Copenhagen is over.
Don’t you agree ?
No. The politics may have shifted a little (although not as much as you seem to think), but the facts haven’t changed. As I’ve said before, the laws of physics don’t change because someone stole a few emails. Climate change remains a huge and pressing problem. Delaying action will only make the end result worse. If they’re lucky, today’s inactivists will not be around to reap what they have sown. My kids will be, and they will spit on all our graves.
“This academic debate re AGW seems passe and irrelevant now that Copenhagen is over.”
Quite right, Mikh, just as the “academic debate” over Hitler’s intentions seemed passe and irrelevant once the Munich conference with Chamberlain was over.
Meanwhile, the planet continues to absorb more energy than it radiates, the ice melts, the ocean acidifies and blind fools such as yourself try to pretend that none of it is happening…
” If you stopped seeing adversaries everywhere and stood back just a little you’d see that you’re active participants in the very thing you deride….” Bandersdad 2 days ago.
Rob and Gareth, it really could be you, and people like you, who are fiddling while Rome burns.
While you obsess with minutiae the world post Copenhagen has changed to make your navel-gazing irrelevant. Even Obama has recognised this and has seen…
“…where the political agenda on climate change was now heading, namely to the developing world, but especially to the East, and to the Pacific Rim…‘Old Europe’, with its love of meaningless targets and carbon capping, will no longer carry weight…”
According to the comment above we are rubbing shoulders with the major players. This blog is subtitled “Global warming and the future of NZ.” Don’t you think it might be time to focus more on the future, rather than the past ?
Global warming is in all our futures. It is (literally) inevitable, and will shape the century. The longer we do nothing, the worse it will be.
Show me how the scientific understanding of climate has changed, and then I’ll revisit Hot Topic’s focus.
“While you obsess with minutiae the world post Copenhagen has changed to make your navel-gazing irrelevant.”
Mikh, if you consider that the planet’s energy balance is “minutiae” and concern for the survival of the biosphere that supports civilisation is mere “navel-gazing”, then you are sadly deluded and I, for one, refuse to join your suicide pact.
IMHO, the common thread that binds Monckton, Wishart and others of their ilk is a pathological narcissism, a desperate craving for attention to mask their core sense of personal inadequacy.
http://en.wikipedia.org/wiki/Narcissistic_personality_disorder
Rob, absolutely brilliant.
Now that wouldn’t apply to say greenpeace stunters, PETA activists, or even, gasp, yourself or the authors of this blog would it ?
No doubt, but then, I’m not travelling the world preaching lies to the ignorant or writing books on topics I know nothing about.
Neither am I proclaiming myself to be an eminent authority on a science for which I have neither performed any research nor published any papers!
Even back in the “Medieval Warm Period”, performers like Wishard and Mockton would have been immediately recognisable for what they are – charlatans.
http://en.wikipedia.org/wiki/Charlatan
“…but then, I’m not travelling the world preaching lies to the ignorant or writing books on topics I know nothing about.”
The sceptical position is certainly getting more publicity and seems to be attracting more support very day doesn’t it Rob ? Even on the front page of dear old granny Herald this very morning. Not yet on their website, but just in case you’re interested it’s headlined “Climate change: another gaffe” and points out that the 2007 IPCC report (peer reviewed) was partly based on a student’s dissertation and an article in a mountaineering magazine.
I’ve just been searching for a Guardian link to the story, but only found news of a new paper (peer reviewed) from Nature suggesting that water vapour not CO2 was probably responsible for 25% of the planet’s warming within the last 10 years. But I guess you, and Gareth and Bryan know that already. Hey, they even be preparing a blogpost on it…
So Mikh, quickly shifting to another topic – away from defending the potty peer and the conspiracist freak – do you hope to find safer ground in actual science?
Clue 1: the IPCC is not the final arbiter of AGW, but a bureaucratic process that reports on the science on behalf of governments. Like all bureaucracies, from time to time they stuff up, make typos, etc, etc. Meanwhile, the planet inexorably warms, ice sheets melt and species march toward extinction.
Clue 2: H2O is a powerful greenhouse gas, but it tends not to accumulate in the atmosphere the way CO2 does (have you heard of “rain”?).
It is the long-term cumulative effect of CO2 emissions that warms the atmosphere, thus enabling it to hold more H2O and engender further warming. This is called a”positive feedback”and is very dangerous – almost as dangerous as the wilful ignorance of your denialist cult.
You mention the “sceptical position” – would that be with your heads in the sand and your arses in the air?
Mikh; thanks for the attribution, well placed I thought. Liked the analogy about Rome even more under the circumstances.
The discussion about Copenhagen interests me given my pre-Copenhagen thoughts regarding the “venue/structure/mechanism” of decision making in a new world of communication. I had suspected that the ability of the old system to cope in the new paradigm was going to be lacking and so it proved. The apparent transfer of some power to the BASIC group I suspect is more indicative of a general draining away of power from traditional governmental structures than a long term geo-political swing. I think it’s most likely to continue to drain from all governmental structures as the world’s “connected individuals” recognise and evolve new ways to use their rapidly changing communication skills.
I still think China will sit up and listen to 100-500 million connected individuals demanding carbon neutral or CRL produts; probably better than they would to Mr Obama…
mikh, just where exactly is your position?
– 1/ Warming is not happening
2/ Its happening but its not caused by us.
3/ It will be good for us.
Also, if you were convinced of AGW what do YOU think the world should be doing since you are so critical of suggestions to date?
Phil I suspect you missed:
4/ Yet to be proven to be happening.
I suspect the dealing in absolutes, 1, 2 or 3 makes no difference, reduces the discussion from communication to advocacy.
I like the question at the end though, very open ended.
Bandersdad, I think it is significant that NZ and India are discussing a free trade deal, and that India,as well as Brazil, South Africa and China are going to be the leading players in this incredible drama we are witnessing and arguing about. I feel too, that the political and economic implications for this NZ India free trade deal are probably much more important to us in the long term than whether or not we agree to any voluntary limits on our CO2 emmissions.
And I agree, ‘connected individuals” have now at their disposal a communications tool that has already changed the world, and will continue to do so. It’s this political paradigm that interests me so much more than the old authoritarian style which many at this blog seem to want to develop even further.
Phil, my position is that global warming/climate change is largely a natural phenomenon, with much of the science behind climate change still to be revealed, and that the proven, habitual record of many that say otherwise, eg Al Gore and NASA’s Hansen is made less credible by their hyperbole and overstatement and a keen desire to resort to fear tactics. Their day is over I think, and the world has moved on.
Have you asked Tim Groser your questions by the way ?
Mikh, I tracked down the article about the climbers’ anecdotal evidence. It originates in the Sunday Telegraph who obviously relish anything they think they can find to denigrate the IPPCC. Talk about magnifying trifles. The two articles are cited in a table entitled “Selected observed effects due to changes in the cryosphere produced by warming.” (You can find it on page 86 of chapter 1 of the report of the second working group on the impacts of climate change if you can be bothered looking.) The observed effect in this case is described as loss of ice climbs. The articles are admittedly anecdotal, but I imagine the IPCC authors regarded that as not unreasonable in a matter more likely to be noticed by climbers than researched in scientific papers. As I have pointed out in a different thread the IPCC reports are not limited to peer reviewed papers as sources. I’ll repeat the extract here:
“The authors will work on the basis of peer reviewed and internationally available literature, including manuscripts that can be made available for IPCC review and selected non-peer reviewed literature. Source, quality and validity of non-peer reviewed literature, such as private sector information need to be critically assessed by the authors and copies will have to be made available to reviewers who request them. Disparate views for which there is significant scientific or technical support should be clearly identified in IPCC reports, together with relevant arguments. Expert meetings and workshops may be used to support the preparation of a report.â€
Maybe the judgement of the authors can be faulted. But the observation relates to a very tiny aspect of the section of the chapter on the cryosphere. You are exaggerating wildly when you say that the 2007 IPCC report was partly based on these articles. Have you ever looked at the IPCC reports? I thought the Telegraph report was making a mountain out of a molehill, but they would probably enjoy that.
Mikh, if Tim wants to discuss, then I would be happy to. However, you did not answer the last question. What would you do if convinced? I am quite prepared to discuss your “natural processes” assertion but if you cannot conceive a world where AGW is real, then the discussion would be pointless.
Bandersdad – if you want a discussion on the science, then you need a starting point. No point starting with evidence that anthropogenic gases are causing warming if you have not first established warming – on so on. Mikh says he is position 2/ Fine. But I am extremely interested in the question as to how people make up their mind on such an issue (ie clearly not on basis of examination of the evidence). From discussion with many people, a bias against say environmentalists, suspicions of world government, a loathing for the suggested solutions (eg carbon tax), affect people’s default position. Now questions like “Should the rich pay more for health care than poor”, or “should justice be mostly about restoration rather than retribution” are not things science have much to say about. They are deeply seated in people’s values and you arent going to change their mind with any argument. When someone’s position on AGW is a reflection of a deeply held value, then they cant conceive a world where it is true and any discussion about the merits of the science is a waste of time. It is only worth correcting invalid arguments least they convince a more genuine inquirer.
Mikh
“Al Gore and NASA’s Hansen is made less credible by their hyperbole and overstatement and a keen desire to resort to fear tactics.”
You obviously haven’t a clue about Hansen’s work. He’s a highly regarded scientist with good reason. Have a look at his essay in the previous post to this one. That doesn’t mean his work can’t be questioned, but statements like yours are not questioning, just parroting the sad ignorant generalised abuse hurled at him by the denialist world.
Phil I agree entirely with the points you raise as they relate to a mechanism of informed debate.
Interesting additional comments for me include:
“I am extremely interested in the question as to how people make up their mind on such an issue”.
1/ But what if they don’t, can’t, aren’t in a position to because they are not equiped to? Science has done itself no favors here and at least is starting to wake up to that fact.
2/ With science itself premised on “the hypothesis remaining unproven to be incorrect” we want people to make their mind up. Bit rich really, why not settling for people being aware of the issues, taking a view etc?
3/ It’s insisting folks take sides again, back to advocacy and debate rather than communication.
“Mikh says he is position 2/”
1/ I didn’t read it that way.
2/ Mikh didn’t say that he was in position 2/.
3/ Your understanding of position 2/ will be yours alone and sure you can start a debate from there but it’ll be founded on a differing understanding from the outset.
“It is only worth correcting invalid arguments least they convince a more genuine inquirer.”
1/ Worth is a value judgement: “not things science have much to say about”.
2/ Correcting invalid “facts”, arguments aren’t often invalid, they’re one of the ways people express their feelings. Mind you I have seen a few duplicitous arguments put up on this site from the deliberately deceitful.
3/Genuine. Hopefully with the exception of the reference above they’re all genuine. Interestingly as I’ve noted before though the greatest time is spend slinging the proverbial at those very individuals.
As I’ve said before this model doesn’t work (well). Maybe if this was a scientific forum charged with debating some arcane edge of science it might (though I doubt it).
Where it is working better, as we’ve established, is where the communication is open, such as:
“Mikh, …, you did not answer the last question. What would you do if convinced?”
Lo…
You touch on what is the very problem with the debate. From science point of view, it assumes that weight of evidence is sufficient. The uncertainty you state it is inherent in science – its dishonest to put up a different position. The problem with the debate on blogs/media is that it is not a debate about science. You have scientists thrust into the unfamiliar and uncomfortable role of advocacy because of all the garbage that is being put out in the guise of contrary view points. I am worried that real science debate (eg the extent of carbon cycle feedback) is going underground because even discussion about the science is seized on by “skeptics” and distorted to all hell. Science sure is trying to find a better way to communicate into this kind of debate but it defies me to figure out what more it can really do. The natural position of scientists is to bicker like hell with each other. Here we have a problem where science is remarkably unified but trying to pass coherent results about an extremely unwelcome problem that we would all rather would somehow go away. Furthermore, the message represents a major risk to shareholder value for some very powerful corporations. How do you think science should be doing it?
And its exhausting debating it. I have the greatest respect for people like Gareth and Bryan, Gavin Schmidt, “Tamino”, etc. who do it day after day. My original questions to Mikh were to a/ look for a starting point for discussion about the science and b/ see whether worth discussing it at all. On this and other forums, I have had both interesting and completely pointless discussions. I am trying to reduce the pointless ones.
Phil…”The problem with the debate on blogs/media is that it is not a debate about science. You have scientists thrust into the unfamiliar and uncomfortable role of advocacy because of all the garbage that is being put out in the guise of contrary view points…”
The science Phil, has been politicised from the very outset, by people like Al Gore, a failed presidential candidate who seems to think that he can raise his profile and make a billion or two by exploiting the science, and hyping it to buggery. It is obviously not only the sceptics who are putting out garbage. You may have more credibility as an individual, and more sympathy from me if you had spoken out prior to this, when Gore was riding on the back of “An Inconvenient Truth”.
Or am I being unreasonable ? maybe you struck a blow for science by pointing out Gore’s errors and overstatements, if so I apologise. But if not, it’s a bit rich for you to claim a moral albeit belated, scientific high ground now.
Science is science, and truth will win out. The science was all settled, according to this blog, anyone who disagreed was a crank, denialist or a flat earther. But now the UK head scientist says that ithe science is not settled and that the sceptical voice should be heard and respected a little. You Phil, speak for science in this debate on this exchange and I ask you, as I have asked Bryan and Gareth, whether you agree with Peddington that uncertainty re climate change, still abounds.
What do you say ?
“The science was all settled, according to this blog, anyone who disagreed was a crank, denialist or a flat earther.” – Mikh
Can I have a strawman alert?.
Note the subtle insertion of “all” before “settled”. That’s the lie, there…
Mikh
“Al Gore, a failed presidential candidate who seems to think that he can raise his profile and make a billion or two by exploiting the science, and hyping it to buggery. It is obviously not only the sceptics who are putting out garbage.”
Your statements on Gore are as disgraceful as those on Hansen, or even more so. He is intellectually and morally out of your league.
Mikh, anything that require political action gets politicised, but if you think climate change began with Gore, then you were living in a cave. It is also completely irrelevant to the scientific question. Science always has uncertainty – you live with it. However I am quite prepared to defend AGW on science grounds and frankly I dont give a stuff for political opinions.
Now, are you answering my question? IF you were convinced that the case for AGW was strong that any reasonable risk assessment would require political action, then what would you do?
Oh, and Mikh, Gore isnt a scientist. What he thinks is irrelevant to the debate. Wild claims by activists certainly arent helping but they dont change the nature of truth.
Phil, its not “wild claims by activists” that should concern us, but the evidence, from the paleological record, of mass extinctions caused by climate change.
http://en.wikipedia.org/wiki/Medea_Hypothesis
http://www.sciencecentric.com/news/article.php?q=07102406
Rob, thanks for the link to The Royal Society study (Mayhew et al). I’ve read a few comments from working ecologists on various blogs over the last couple of years, and they seem rather frightened by the changes they’re seeing.
Rob, I appreciate the dangers but I am not keen on exaggeration either. I could be wrong. Someone commented that the science position is cautiously predict 3 degrees and hope its not 6 while joe public reads this and says well denialists say zero so answer probably 1.5 – not too bad. However, what is the importance of credibility? If you overstate a case, then it is easily shot down by critics. For someone neutral, what is more convincing? – science says 3 and on examination you find it could be 6; or someone screaming 6 and you find it is more likely to be 3? And for activists, I would have thought the neutral middle ground is what is important in most debates. You wont convince people with embedded positions so I would say honesty works best for the concerned citizen looking for information.
In a newspaper debate, someone cited a greenpeace website claiming Indonesian peat fires were responsible for 40% (I think – not remember detail) of CO2 emissions. Well the only papers I could find estimate that in one bad season between 5 and 40% of the regions CO2 emissions were from peat fires. Well meaning activism but not helpful.
I have similar misgivings about attempts to move governments by just pushing worst-case scenarios.
There are great points here Phil.
Credibility and honesty have to be paramount as you say. Moving government is, also as you say, problematic. Government is just a representation of the people though and I beleive that’s the point that’s missing. Governments will do what the people tell them (no, I’m not an idealistic idiot); if done well. It comes down to communicating with that public and creating the community of conected individuals who create the result; naturally enough through some great piece of political leadership…
Interesting conversation. Getting governments and the governed to act on an issue like this is obviously not trivial. A perfect government would look at the evidence, note the need for action, and set about building a consensus for sensible policy creation. Any policy put in place has to be sustainable — capable of surviving long term, and over many electoral cycles — so imposing something because you can win a narrow majority in parliament is not likely to be a successful strategy. There has to be a continuing large majority of politicians and voters who support action on climate change.
Building that sort of consensus is clearly non-trivial, but I don’t think anyone in New Zealand politics has even tried. The last Labour government built a reasonably sensible interlocking set of policies, but made next to no effort to sell the need for action. The current government understands this need in other policy areas — they’re happy to spend $26m this year promoting the “need” for national educational standards, for example. A similar sum spent on building a consensus for action on climate could work wonders. Sometimes leadership means taking a lead…
So in your mind it all comes down to spending on marketing so we are ‘all on the same page’?
Marketing’s a part of it, sure, but it’s not the only thing. It sounds trite, but we need a “national conversation” on climate change (France did something like this with its Grenelle Environnement in 2007). But any sensible discussion means accepting some common ground.
I beleive we’re getting closer to the point I’ve been stressing about communication. We need to build a new model of effective communication with the populace. Power will ultimately then reside with them. We already know they all want their kids to grow up in a world without catastrophic climate change.
Marketing is, as you say,a part of it. In a good way though rather than the “other” way. I also like very much the idea of a “national conversationâ€, sounds very much like what I’ve had in mind.
Phil, I think you are mistaking me for another Rob Taylor who works for Greenpeace, but I am not he.
I do, however, have honours degrees in physics and mathematics, plus 30 years of experience in government, politics and business. Given that background, I believe I understand the science and politics well enough to see the clear and present danger of where we’re headed.
For example, here is an extract from the 19 March 2009 letter to Nature by Tim Naish et. al, re the results of the ANDRILL programme on the Ross Ice Shelf:
“Our data provide direct evidence for orbitally-induced oscillations in
the WAIS, which periodically collapsed, resulting in a switch from
grounded ice, or ice shelves, to open waters in the Ross embayment
when planetary temperatures were up to 3 C warmer than today
and atmospheric CO2 concentration was as high as 400 p.p.m.v… The evidence is consistent with a new ice-sheet/ice-shelf model that simulates fluctuations in Antarctic ice volume of up to
+7 metres equivalent sea level associated with the loss of the WAIS and
up to +3 metres equivalent sea level from the East Antarctic ice sheet, in response to ocean-induced melting paced by obliquity.”
If a slow orbital forcing can accomplish that, is it not realistic to expect that the relatively precipitous shock of AGW can do the same, if not worse?
Furthermore, is it not possible that AGW will trigger the Arctic clathrate gun, ushering in another mass extinction?
http://en.wikipedia.org/wiki/Clathrate_gun_hypothesis
I believe these to be prudent, mainstream concerns rather than exaggerated or “alarmist”, particularly as I have children and potential grandchildren to consider…
Rob, I am not confusing you with anyone. I didnt know there was a Rob Taylor in Greenpeasce – the greenpeace example was merely one example and just one off the top of head, of where you have activists going in for exaggeration to push a point at the expense of credibility. The problem I think with climate change is that it is a slow process. It will be a problem for my children and grandchildren but I doubt it will personally impact me much. Getting people concerned about a problem that will affect the next generation most isnt easy and that is why I think there is a tendency among activists (not scientists) to overstate the present danger.
And yes, there are nightmare scenarios, especially clathrates which my section is actively involved with. However, so far the evidence doesnt point to this being a likely scenario – though we are pretty short of data to be have any kind of certainty. http://www.sciencemag.org/cgi/content/abstract/324/5926/506 was disappointing for me as clathrate release would other explain some interesting problems in paleoclimate. 6 degrees by century end is, so far, on the upper end of the predictions so not that comfortable with pushing that as likely. As you point out, its not like 3 degree is a picnic cf natural rates of less than 1 deg per 1000 year. I am not advocating understating the risks either.
As a result of Frank’s work, the amount of additional CO2 expected to be released in response to a temperature rise is now 8ppmv/°C instead of 40ppmv/°C.
This seems to reduce by 80% any likelihood of chain reactions, which have given rise to anxieties about “catastrophic” future warming. It should also markedly extend the period before the verboten 450ppmv is reached.
Australis – as far as I can see from the documentation, the CO2 scenarios used in the IPCC models do not include any CO2 feedback – I think they also assume that planet will continue to absorb CO2 at current rate. Most if not all of the AR4 models ignore GHG feedback as these are believed to be long term, not short term feedbacks. The futures outlined in the AR4 IPCC impacts reports are uneffected by this – whether you regard this as “catastropic” is relative I suppose.
At least some AR5 model will include carbon feedbacks from what I have heard, so this and many similar papers will be relevant to the next report.
Its also very hard to explain the PETM event without something like hydrate release so lets not be complacent either.