Bishop Hill NIPCC interim report 2011
Aug 30, 2011 
The Heartland Institute's NIPCC interim report has just been published - see here. This is a summary of the new scientific literature since 2009.
I've taken a glance through the paleoclimate bits and it appears to have been put together in a very professional manner. I was blissfully unaware of just how much evidence has been emerging for the existence of a MWP in the world outside Europe.
If I had a criticism based on what I have read, I would say it's over the authors' tendency to slip into editorial mode - discussion of Mann being engaged in "subterfuge" looks out of place in a scientific report.
Lots of people are not going to like the report of course. Peter Gleick, the president of the Pacific Institute, tweets that the report makes him sick and refuses to link to it. Barry Woods and I have politely asked which bits in particular he is concerned with and he has told us that he doesn't need to do this when someone is arguing that the Earth is flat.
Reader Comments (144)
Perhaps we can create a new term for Peter Glecik .
He appears to be the osterich in the room.
I haven't read the report yet but it sounds interesting.
PS I think "an MWP should read "a" MWP
[BH adds: the style on this blog is to write it the way you would say it]
Does Peter represent USA climate science?
Quotes elements of Heartland as 'sick' publically on twitter, doesn't link, when politely asked for page number and paragraph, refuses and starts linking sceptics to flatearther comment and tobacco link thrown in,
He publically states it is LIES and misrepresentations (smearing them) at least unprofessional, look at the 'scientyists' that contributed to the report.
PeterGleick Peter Gleick
#heartlandinst still deny climate change in recycled 430-page compilation of lies, bad science, misrepresentations.Shocked.No link needed.
Dr. Peter H. Gleick,
President of the Pacific Institute for Studies in Development, Environment, and Security.
http://www.pacinst.org/about_us/staff_board/board.htm
I expect a lot more of someone in his position,
PeterGleick Peter Gleick
@ @mrsean2k @Adissentient @realclim8gate No need for me to disprove arguments that smoking causes cancer, again. Same with bad climate rpt.
PeterGleick Peter Gleick
@ @Realclim8gate @Adissentient When someone argues earth is flat, why should I specify page and verse in rebuttal? That's this NIPCC report.
Peter went onto Twitter publically denounced a Heartland Institute, said the bit's he read made him feel sick, but was unable to quote pg number and paragraph, so anyone who read his public pronouncements, to look for themselves..
If that is the culture in his workplace, no wonder there are no sceptical more 'junior' voices.
very sad, the UK is NOT like this.
Peter Gleick has over a thousand follower, with media and climate scientists very well presented.
media including
Richard Black(BBC), Adam Vaughan, Leo Hickman, And Revkin (Dot Earth NY Times)The Carbon Brief
scientists including:
Ken Caldeiar, Scott A Mandia, Katherine Hayhoe
https://twitter.com/#!/PeterGleick/followers
If Peter PUBLICALLY tweets to these people taht the Heartland Institution is publishing lies, bad science and misrepresentations, parts of which make him 'sick' At the very least I would hope that his scientific collleagues, would ask for a page number paragraph as evidence...
I hope the worlds media representatives following his tweets would take notice of his refusal to do so.
The first two links to Gleick's tweets compute but the third doesn't. Presume you want
https://twitter.com/#!/PeterGleick/status/108324760429150209
Good that such people are responding to questions on Twitter, by the way. The old arguments from analogy - flat earth, smoking/cancer - are out in force I see. Rather easier than showing that NIPCC is less balanced than IPCC on such a complex subject.
Well said Bish. I'm personally tired of the "Mann derangement syndrome" that takes the place of reasoned criticism. We should all just accept that a young professor who got his flawed thesis passed during the height of a period of alarmism, and ascended the stage of fame, will defend that thesis to the end and make sure that the sceptic criticisms are based on facts.
I'm not surprised Gleick is feeling sick.
He's watching his entire belief system coming apart in front of him.
Has he not learned yet that investing as much of your life in one single cause for anything as he has done is sooner or later going to turn out badly?
That is one very frightened man and I actually feel sorry for him.
His adoring and unquestioning acolytes less so.
I have to be honest and say I think the report is abysmal. It is a set of spliced together criticisms with no overall structure. It doesn't explain what it is trying to known down ... it just .. well, all it says is "it's knocked down".
This is not the way to win a debate.
For example on forcings, it starts .. "In a paper that appeared in the 15 October 2010 issue of Science, Lacis et al. (2010) claim atmospheric CO2 is the ―principal control knob governing earth‘s temperature...All else being equal, their conclusion might be correct. However, ―all else being equal‖ is rarely the case in the real world"
At which point it starts talking about CO2 being a plant food. It might somewhere have gone into climate forcings, but I have to admit I'd given up the will to go on.
Honestly, how difficult it is to state that "physics accounts for less than 1C of the 2-6C of warming and the rest is at best a 'guess' based on speculative positive feedback". OK, I know spencer backs that up, but presumably there is some evidence or at least argument backing up their assertions of massive positive feedbacks.
As, this is the knub of the whole climate debate, I didn't expect to have to dig like some archaeologist to find it in the rubble of the argument.
Peter publically to the world accuses the Heartland Institute of Lies... I wonder if his fellow member of the Pacific Institute approve of his public twitter announcements?
Alongside Peter Glieck at his institute is Dr Anne Erlich, wife to Paul Erlich
http://en.wikipedia.org/wiki/Anne_H._Ehrlich
Works jointly authored with husband Paul Ehrlich:
Population, Resources, Environment: Issues in Human Ecology Second Edition (1972) San Francisco: WH Freeman and Company
Human Ecology: Problems and Solutions (1973) San Francisco: WH Freeman and Company
Earth (1987)
The Population Explosion (1990)
Healing the Planet: Strategies for Resolving the Environmental Crisis (1991)
The Stork and The Plow: The Equity Answer to the Human Dilemma (1995)
Betrayal of Science and Reason: How Anti-Environment Rhetoric Threatens Our Future (1998)
One With Nineveh: Politics, Consumption, and the Human Future (2004)
The Dominant Animal: Human Evolution and the Environment (2008)
http://www.pacinst.org/about_us/staff_board/board.htm
Another Pacific Instiute Board of Director is Dr. Robert Stephens:
"he is currently the Chair of the International Committee of MSWG and serves as Secretariat to the United Nations Environmental Program, Best Practices Network for Sustainable Development."
I think the report could be better written, much more dispassionate, etc,etc..
Peter Gleick's reaction is fascinating though, I wonder what his twitter followers make of it and his reaction? ie Richard Black, Leo Hickman, Adam Vaughan, Andy Revkin, etc..
@Barry Woods Aug 30, 2011 at 8:55 AM
Barry, I follow a lot of different voices from across the 'climate debate' on Twitter - as you might expect. Besides Gleick and a range of climate scientists, I also follow people such as you, Watts, Heartland, Delingpole, Corbyn, the author of this blog, to name just a few. I even followed Lord Monckton for the single day that he joined Twitter before he abandoning it! (Anyone I've missed but should be following?? Is there a register anywhere online of all those 'climateers' who are now on Twitter?) Of course, this doesn't mean that I agree with the views of all that I follow - or feel that I'm unduly influenced by what they say. Twitter is simply a very convenient way to keep on top of what everyone is saying/doing - and provides an excellent informal arena for dialogue that might not otherwise occur.
Leo Hickman (@LeoHickman)
Aug 30, 2011 at 9:40 AM | Leo Hickman
Love your work Leo - you are an extremely talented and principled journalist
Keep up the great reporting.
@ZedsDeadBed Aug 30, 2011 at 9:48 AM
Thanks. I must admit, I didn't expect to see a comment like that ever posted here, but I'm grateful for all compliments - wherever the venue ;-)
If others are also "blissfully unaware of just how much evidence has been emerging for the existence of a MWP in the world outside Europe", there's a catalogue of literature about the MWP on the website co2science.org
I will read this. I did actually find the 2009 quite interesting and even useful in some places, although (as BH says about the 2011 report) the writing style is sometimes not very scientific - they make similar "judgemental" statements about IPCC as BH says they do about Mike Mann. As The Leopard In the Basement says, it would help with general credibility of reports such as this if it wasn't so overtly political and just focussed on objective discussion of the literature.
(Then again, I suppose you could argue that the report has a particular audience in mind and wishes to speak to that audience - but the trouble with that is that it then alienates other readers, and ultimate IMHO undermines the report's credibility.)
NIPCC(2009) also often drew conclusions from published studies that were not supported by the authors of the original studies, and in some cases made judgemental comments about that - eg: page 65 "nevertheless, Siegenthaler et al stubbornly state that the new findings "do not cast doubt...on the importance of CO2...."
And also they sometimes seem to present the IPCC's conclusions as being different to what they actually were - eg: again in the above example on page 65 they talk about "the IPCC's claims that the CO2 produced by the burning of fossil fuels will lead to catastrophic global warming" - I'm not sure where in any of the assessment reports that actual conclusion is stated, especially with focus on "will" and "catastrophic" (but I'd be interested to be pointed to where this is!).
In the 2009 report I found chapter 7 on "Biological Effects of Carbon Dioxide Enrichment" particularly interesting, as there was a lot of debate on the coverage and conclusions on this in AR4 (amongst the authors as well as reviewers) - and indeed it's one area where there seemed to be inconsistencies between WG1 and WG2. Funnily enough, the NIPCC chapter opened with a copy-and-paste of a piece of my text from AR4. Who knows, maybe the 2011 report will point me to some useful material for me in my contribution to AR5?!!
My main overall criticism of the 2009 NIPCC report, other than it's obvious political style, would be that it doesn't really present a coherent, quantitative argument, it just lists different pieces of research. IPCC brings together the literature and comes up with a quantified and (usually) traceable view on what it actually means, backed up with many many tables and figures. NIPCC (2009) doesn't really do this - it generally just reproduces figures from papers, without cross-comparing with others, and even then the figures are relatively few, and unless I have missed them I don't think there are any tables other than the massive Table 7.1.1 in Appendix 2. So overall it is nowhere near as deep and rigorous as IPCC. (NB I'm still talking about the 2009 report here - I've not read the 2011 report yet)
(OK the "traceable view" may not always be perfect in IPCC, but it's much better than in NIPCC).
The extent to which the NIPCC reports represents a substantial body of informed view is not clear either. The 2009 report had 2 Lead Authors, about 35 "Contributors and Reviewers" (no distinction made between these groups) and 2 Editors. Contrast this with the huge numbers involved in IPCC, who engage in a detailed cross-fire of debate both as authors and reviewers (we don't just sit around for 3 years agreeing with each other...!). I'd have thought that, given the amount of literature cited, more people could have been involved in checking that the literature was appropriately represented.
So if the Heartland Institute wanted to create a document that could be viewed with the same standing as the IPCC Assessment Reports, in my view they didn't manage to do it with the 2009 report. However I will look at the new report and see if they've made any progress.
Aug 30, 2011 at 10:20 AM | Richard Betts
Seemingly I'm all about the love today.
The criticism I most often make of this place, is that for so called sceptics, there is often very little actual scepticism applied. It tends to be 'against AGW = good, supports AGW = wrong'.
But there are actually a few good comments here prepared to apply genuine and balanced scepticism to something you should all nominally be 'for'.
I applaud the attitude and the comments.
I feel you should all go further, and apply the same scepticism to some of the comments and attitudes exhibited here. I doubt many of you seek my approval, but the day that you get something like Peter Walsh citing the Oregon Petition, and the overwhelming flaws in that work are pointed out, I shall be very impressed.
Until then, the comments here have slightly raised my estimation of this blog.
That's a funny conincidence. I was just this week reading a scinetific publication by Gleick - about water, nothing to do with climate. Seemed a perfectly good paper, but will re-read from a different perspecitve.
Zed:
On the contrary, my friend, many of us have barely found the will to live without it.
It's good to have Leo Hickman over in passing. I agree that you can't judge a man by the monikers he follows on Twitter. I remain fascinated with the fact that with Leo I know the real world character represented (though impersonation is hard to rule out in theory, it's unlike in practice) but with Zed I don't. Yet the praise of Zed obviously meant a lot to Leo - someone who has called for real names to be used where possible on climate blogs. And that's partly because it's comes from Bishop Hill.
I don't think every piece of this emotional reaction is rational. I note it without rancour, however, as a good scientist should.
And you're right to praise people for criticising the NIPCC here, Zed. Hopefully the criticisms are more balanced than the report and thus we can get closer again to reality. As I alluded to earlier, with something as complex as climate - both in its dynamics and its impacts on humanity - it's not easy to know when one has achieved balance.
Hey Leo. I know you are your own person, and I know you follow lots of people, you even chat with sceptical me..
I just wonderedwhat you thought of this guy?
Ie a scientists who was poltely asked for the pg number and paragraph (by ishop Hill), that he had a problem with, and he refuses.. !
He went onto twitter to publically 'brief' his followers about Heartland 'lies' but refused to show what was wrong..
JUst Curious to think what journalists and scientist make of this...
Leo Hickman so what do you think of Peter's comments , and you not told us what you think about the reports contents ?
As for complements, you get all sorts of views on here its a fairly free exchange place. Unlike places like RC with CIF environmental has chose to partnership with and to promote, were party line is enforced . So it may comes as shock to you it does but it does not to most people on here.
Leo, I'm NOT criticising you, I follow Peter and lots of interesting people as well..
What was interseting, was Peter's reactions...
I've had a brief look at the Heartland thing, and personally I'm not impressed with the style, should be written far more disppasionatley.
The diference is I think, it is an American institute, and climate scient politics, seems to be much more nastier and perosnal, also across a political divide, than the UK...
@Barry Woods Aug 30, 2011 at 10:57 AM + @KnR Aug 30, 2011 at 10:58 AM
I haven't seen/read the Heartland report, tbh. My views of Heartland are well documented ... http://www.guardian.co.uk/environment/blog/2011/jul/19/climate-change-wiki-heartland-institute ... and I'm not at all surprised that Andrew and others here have already made the observation that it slips into "editorial mode", to put it politely. I'm not surprised, therefore, that Gleick would approach the report at arm's length and with a degree of suspicion/scepticism, but if he has read it and feels "sickened" by it I personally can't see why he would object to citing the places that make him feel most ill.
You never if you only read what AGW proponents had written you be hard pressed to remember that the MWP was the scientific consensuses and there was good evidenced to support . Until that is the current climate changes needed to 'unique' in history for political reasons so the MWP needed to disappear, step forward hockey stick Mann and magic trees etc.
So its hardly a surprise the evidenced is building up again it was very real and widespread. The irony is that does not meant there can't not be AGW .The problem that a MWP is seen as no AGW , and so the need to defend the indefensible to the death , is very much of the AGW proponents own making knowing their case was weak they need to bolster it anyway they could , especially if they wanted to achieve their political goals, and so the idea of 'unprecedented' was born and need to ditch history was created .
Leo Hickman you haven't seen but you know it can't be good and you nothing to say about the silly insults and allegations from Peter Gleick, 'arms length' of course does not involve such approaches so the idea his arms length makes no sense .
I wonder will we ever find out who on CIF feed Bob Ward 'the article' before publication , against CIF own claimed ethics , what do you think Leo?
I don't hold Leo repsonsible in any way for other Guardian articles, he is not he editor.
That would be for a question best directed to James Randerson - ref here...
http://www.bishop-hill.net/blog/2010/9/10/can-one-trust-the-guardian.html
Leo probably hasn't seen all of Peter Gleick comments either, ie lost in voluminous twitter stream.
Leo
I also have some doubts about the way that the Heartland Institute puts forward the sceptical case. As someone has already pointed out the fight in the US seems to be dirtier than it is over here. That said, the glee with which some sceptics latch onto anything that appears to weaken the AGW case (like the Met Office report on the current summer, for example) is at least matched by the determination of the AGW supporters to denigrate and sneer at anything that threatens their comfort zone (like Svensmark and the CLOUD experiment, for example).
There is still a case to made that the alarmists are wrong and for Gleick to accuse me of thinking the earth is flat or that I do not believe that there is a link between tobacco and cancer just because I take a different view on global warming from him is something I find offensive.
I'm not much of a psycho-analyst but speaking as a parent, he is behaving exactly like any eight-year-old who is being told that some cherished belief is not quite what he thought he was. Stick your fingers in your ears; refuse to acknowledge the existence of the other point of view; shout and scream and insult. I think most fathers would recognise the symptoms.
If his view of global warming is right he has no need to feel sick because someone thinks otherwise; ignore them and carry on. If on the other hand he is wrong, tantrums will not, in the long run, save him.
Richard Betts
There may be valid criticisms of the polish and flow of Heartlands reports, and certainly occasional outbreaks of speen venting should have made it into the final draft, but what it seeks to do is bring back some needed balance to the importance of natural processes of climate variability. The IPCC reports are undeniably slanted to highlight anthropogenic influence, that is their political mission. In doing so the bias is endemic, and was recognised by the House of Lords as such back in 2005.... Ch7 The IPCC Process para 111. 'We can see no justification for this procedure. Indeed, it strikes us as opening the way for climate science and economics to be determined, at least in part, by political requirements rather than by the evidence. Sound science cannot emerge from an unsound process.'
Things have probably gone too far for a non political independent audit to be possible, at least in the West. Paradoxically, perhaps the only scientific institutions now capable of such an audit are to be found in the former soviet bloc. Indeed the political canker has progressed so deeply into the heart of climate science that probably the only ultimate solution in science is to redistribute the appropriate disciplines back to their traditional components- meteorology, oceanography, geology, atmospheric and astronomical physics etc.
Newspapaers are complicated beasts..
A personal experience, a school dad, dad of my 7 year old daughters friend. I found worked at The Telegraph. I mentioned that I'd seen Christopher Booker, speak at the House of Commons.
the response from Telegraph colleague, was 'Booker, he's a bit of a denier, isn't he?..'
I dropped the topic, it was at an Infants schools gates. ;)
Let's not dump the perceived 'sins' of the Guardian onto Leo Hickman... I doubt that he even gets into the Guardian offices that much. He has an open enough mind to at least read Bishop Hill / Watts Up, etc on a regular basis.
Barry Woods I just think Bob 'fast fingers ' Ward should get the credit he warrants., as after all a typing speed of over 300 wpm is much better than the current record . And unless someone did pass him the article before publication that is the only explanation.
Given that just asking this question on CIF gets your accounted deleted and especial given their track record of vilification of AGW skeptics., who can forget Monboits AGW Skeptics should be treated like Holocaust deniers idea. I don't think we need to give Leo and the rest of the Guardains environmental journalists to much credit on any front. As their happy to play bully when they can on CIF , while ducking and diving when they can't as on here and Leo's inability to address Peter's actual insulting remarks.
Anybody on our side claiming that the earth is flat..?
Thought not...
I haven`t had time to read the Heartland report, but I do read the leaders occasionally and agree that they do tend to be less than dispassionate in their science. Then again I have never, rightfully, pointed out the flaws in a report on tobacco smoking and been tarred as a supporter of big tobacco for the rest of my life.
Richard Betts. You know my feelings on the work of WG1 and the totally misrepresented output of the work. Not sure about the outputs from WG2 and WG3 which seem to be the work of Greenpeace and the WWF. I asked you a question on the unthreaded blog some time ago, to which you were gracious enough to reply, and which, due to time constraints I was unable to read in depth. with the Bishop`s permission I`ll ask it again, hopefully making my point clearer.
1. Assuming that the global average temperature is indeed 15C. And further assuming that the adiabatic lapse rate is 2C per 1000 feet then, all other things being equal all glaciers above the height of 8000 ft would be below 0C all of the time.
2. The only mechanism for the glaciers to recede that I know of is ablation, but as far as I know ablation can only take place in the absence of precipitation;
3. It is accepted be all that global warming will cause more precipitation, but the glaciers are retreating, including some above 8000 feet, I`m not stuck on that number if you want to argue the point, just use your own number and explain why glaciers that are in temperatures that are always below freezing are retreating when precipitation should be advancing them.
Much obliged Dr Betts, you are most welcome on these pages.
Barry: you say. "Let's not dump the perceived 'sins' of the Guardian onto Leo Hickman..."
I'd agree if I'd ever noticed any evidence that he was in the slightest bit concerned by the general tone of Guardian AGW pieces. On the contrary, he is one of their most fervent evangelists, so I don't see why he should be absolved of any justified collective blame.
I agree with other commenters here that tone is an issue, not only in these reports, but in many other writings, on all sides of the argument. Similarly with "playing the man, not the ball." Although in this case Heartland appears to be playing the Mann; others play the Ball.
It seems to me that an antagonistic tone is relatively easy to proof-read out of a document. Perhaps Heartland should make that an explicit writing style goal, and place that high on the list of review criteria -- I'm assuming that the reports go through one or more internal reviews before release. [The criticism about organising the arguments requires more editorial help.] Bishop, I should think that your voice would be listened to in this regard.
It would be a great improvement -- at least a relief to my ears! -- to get the debate on a higher footing. One must start somewhere.
you only tempt people over to the 'dark side of the farce' by being polite, civil and making an interesting argument..
(farce - quoting an amusing comment, at Climate Etc)
I don't know Leo, just think he sincerely has a position.
I do know, my sister in law, A Green Press Officer and a very nice person, ergo, 'I know' people can be nice even if you think them wrong on an issue, I'm sure we all have our little blindspots.
HaroldW: I'd never seen Mann and Ball before. Brilliant.
They have certainty. We only have doubt. Whereas a report by the IPCC can dismiss or ignore doubt and press the case for warming, the inexorable chain of logic that goes from radiative physics to global disaster, amy report even trying to oppose that train has to deal with doubt. That is, to introduce any and all evidence which will undermine the certainty or the connections in the chain. In proper scientific discourse, that would be all that was needed, and the debate would end with a degree of uncertainty, and 'more research is needed'. This is not a scientific discourse. Our doubts are not to be entertained, they are mere expressions of denial. It would not matter what honest data and opinions were in the NIPCC report the warmists cannot accept doubt, and that is of course a political stance. Useless to debate the nits in the report, the better it was the more they would not want to read it.
Rhoda
Agree absolutely except for one minor — but crucial — point.
Your last clause should read "the more they want not to read it". There are numerous things around that we may not want to read but in order to maintain a balance we do anyway. When we start on the road of actively "wanting not" to read something we are closing our minds, a situation that alarmists, by and large, have got themselves into.
It's not a healthy state to be in, especially for a scientist.
"Barry Woods and I have politely asked which bits in particular he is concerned with and he has told us that he doesn't need to do this when someone is arguing that the Earth is flat."
In other words, I haven't actually read the report.
Not quite, Fred. He's read enough to make him feel sick. (Like Violet Elizabeth Bott!)
But he doesn't actually need to read it because it's from the Heartland Institute and therefore must be wrong.
As I said earlier, they are not my favourite people when it comes to putting forward a sceptical argument but I still claim that the reason Gleick would rather cut his own throat than answer Barry and the Bishop's quite reasonable suggestion that he point out where the report is actually in error is because he might find himself involved in a debate which he might conceivably lose.
Perhaps some other supporter of the "consensus" might like to hold their nose and read the report and tell us where these errors are. I'll listen to anyone's argument if it is honest and makes sense.
Gleick blogs for the local birdcage liner's website; I read his pieces occasionally.
I hate to say "usually for their comedy value" but that's pretty much how it works out.
*sigh*
Journalism, we hardly knew ye.
As these arguments grind on, I find myself wondering why nobody is asking the obvious question about the MWP. Namely that whichever attribution one favours, the actual forcings and feedbacks suggested are not especially large (eg increased TSI, decreased volcanism, NA warm water). Which is strongly suggestive of a relatively high climate sensitivity.
So, arguing for a pronounced, global MWP (which the evidence appears to support) is arguing for a high climate sensitivity. This is not compatible with 'lukewarmerism' which is one of several reasons that I have had to abandon this position recently. With considerable regret, but that's how it goes.
BBD, a nice comment at Judy's shows that the two tribes are using different meanings of 'climate sensitivity'. Every fifth drum is parallel.
==============
I strongly recommend Richard Lindzen's very honest presentation on climate sensitivity and how we are beginning to be able measure it, both from outgoing radiation (using data from ERBE and CERES) and surface evaporation. That was part of the American Chemical Society's webinar two days ago, with podcast (video or audio) promised soon.
There are difficulties enough with establishing sensitivity today, with all the data we have now, as Lindzen makes very clear, not least because of the challenges knowing when the system has returned to something like equilibrium after an increase in surface temperature. In the light of this, and given how little any of us knows about the drivers and forcings acting in the medieval period, how anyone can be convinced of a high value for climate sensitivity based on the MWP is beyond me.
I'd rather be a 'scientyist' than a 'climatologist'.
The scientyists seem much keener on the scientific method.
Richard Drake
It's self-evident. A variable climate implies a high sensitivity. MWP QED.
Consider further. A low climate sensitivity means that eneregy is shed efficiently and does not accumulate significantly in the climate system if forcings increase. Agreed?
So, assuming a low climate sensitivity, how does a moderate change in solar forcing from orbital eccentricity (Milankovitch) terminate a glacial?
kim
A link would be helpful.
BBD, I note you're now changing the subject to how a glacial ends. I don't know the answer. Are you really more confident of estimating climate sensitivity in the distant past, knowing so little of what was going on, that from today's copious satellite and other measurements?
Richard Drake
I'm not changing the subject - climate sensitivity determines climate response to changing forcings, be they Milankovitch or whatever it was that caused the MWP.
One needs to answer the question: assuming a low climate sensitivity, how does a moderate change in solar forcing from orbital eccentricity (Milankovitch) terminate a glacial?
Ron Cram at Climate Etc on climate sensitivity (during the course of an interesting discussion):
http://judithcurry.com/2011/07/30/spencer-braswells-new-paper/#comment-92188
BBD, are you referring to climate sensitivity to a doubling of CO2 specifically or to other sets of factors?
woodentop
From Ron Cram's comment:
Orbital dynamics (Milankovitch) provide a coherent explanation for the onset and termination of glacials.
Nobody is arguing that CO2 is 'the only driver of climate'. It is one of many, but the unusually high current level means that it is beginning to become dominant.
Dave Salt
It doesn't make any difference. You can warm the climate system by increasing TSI and surface insolation goes up by x W/m2. Or you can increase RF by increasing the atmospheric fraction of CO2 and DLR at the surface rises to x W/m2. The global average temperature will rise by the same amount. Just think of it in terms of energy in vs energy out.