Thursday
Apr052012
by 
Bishop Hill
Bishop Hill Greenhouse reversal
Apr 5, 2012 Climate: other A new paper in Nature reports that the temperature-leads-CO2 effect seen in the Antarctic ice cores reverses when the analysis is extended to the globe as a whole (report here).
The new data is from northern hemisphere ice cores and proxies from other places around the globe.
A new, detailed record of past climate change provides compelling evidence that the last ice age was ended by a rise in temperature driven by an increase in atmospheric carbon dioxide.
The finding is based on a very broad range of data, including even the shells of ancient tiny ocean animals.
According to the BBC report, "the study covers the period in Earth history from roughly 20,000 to 10,000 years ago".
Lots of questions occur:
- we are comparing proxy-derived temperature readings to proxy-derived CO2 readings - presumably big uncertainties?
- how were the proxies selected?
- why the period selected - does the relationship hold outside this period?
Interesting stuff.
Reader Comments (80)
We must get rid of the MWP
We must get rid of the 800 year lag.
How long before we get rid od the last 15 years of stall.
This report is misleading because it concentrates on CO2-T behaviour during the warming period after the ice age has been ended, i.e. the planet is heading to the higher temperature lobe of its bistable climate state.
Stott 2007 shows that the warming of the deep Southern ocean Starts 2 ky before any significant rise in [CO2]**. My research suggests it is due to a reduction of cloud albedo [3.5% fall in average cloud albedo =~ the 2.88 W/m^2 extra forcing claimed by the IPCC for GHG-GW from the Last Glacial Maximum to the pre-industrial age].
The warmists are using it to justify the claim that CO2-GW is responsible for most end of ice age warming: not proven because of the error uncertainties.
** The regional warming in the Southern hemisphere associated with Milankovitch tsi increase is phytoplankton-bloom related - it gives a global 20 ppmV [CO2] rise but you have to wait to the 100 ky year time before the ice ages end [used to be 41 ky before the Isthmus of Panama formed.]
I hope it turns out to be interesting scientifically for climate studies and not for pathology ones.
I fear there are many people who desperately want such an example because the case for their beloved crisis has long been weakened by the geological records indicating CO2 variation as a response to temperature variation.
There is a bizarre reversal of cause and effect in the report.
It seems that the melting ice resulted in salinity changes that resulted in more warming in the south, hence the increase of Antarctic temperatures, and subsequent outgassing of CO2 which lead to global rather than local warming.
But it all starts with the melting ice in the north! Which implies to me that is was already getting warmer globally before this chain of events starts.
If Antarctic temps preceded the CO2 rise, and global temps followed it, does it mean Arctic temps actually went down as CO2 was rising at first? As in, the exact opposite of what is happening now.
Anyway...at the end of the day, it's still just-so stories. I wish climate science graduated away from them.
"At the end of the last ice age, CO2 rose from about 180 parts per million"
I bet the plants were hungry.
The end of the ice age is triggered by biofeedback in Antarctica. The process has to retrigger the ocean currents to transport nutrients to the tropics so phytoplankton can reduce cloud albedo there.
700 years later, that extra heat input causes CO2 starts to rise and the Northern hemisphere also starts to warm.
We don't need to get into complex arguments about the uncertainty of proxies to see co2 lagging behind temperature changes in the modern instrumental record:
http://tallbloke.wordpress.com/2011/06/26/which-causes-which-out-of-atmospheric-temperature-and-co2-content/
If its being carried by the BBC you can bet your bottom dollar that it's been put there deliberately to prop up the creationism called Mann Made Global Warming (tm). This is purely there for ideology and NOT for it's scientific merit!
Mailman
See WUWT for more demolition.
Basic question. Where did the increase in CO2 come from?
Not answered so fail.
P
First impressions judging from the info from the BBC article it's interesting that the Antarctic Temp pre-date graph seems to have the CO2 and temperature clearly following a similar close tracking shape - which to my mind imply a simple strong relationship. The new "improved" narrative showing the later graph has a temperature shape more smoothed, less neatly following the CO2 changes. Seems more "forced" and less intuitive.
I didn't think WUWT had a very good overview of the paper, rather unfocused and muddled. I'd like see a sceptic go through it in detail for the layman.
No matter how convoluted the argument, the extra CO2 still has to come from out-gassing from the oceans. Which means the oceans need to be warming by that stage. A cynic might ask, if the oceans were already warming why do we need CO2 to explain the warming since it already occurred, and how does this escape from the problem that CO2 follows and not leads?
The oceans warm because of reduced cloud albedo.
CO2 outgasing is a follower.
Net CO2 climate sensitivity might be kept to zero by negative feedback/no direct thermalisation.
@paul maynard
'Basic question. Where did the increase in CO2 come from?'
To paraphrase quantum mechanics and Big Bang theory, it was 'borrowed' from the future increase that would occur when the Ice Ages melted sufficiently to allow humans to start the Industrial Revolution and so bring eternal warming misery to all the life forms of the planet.
Which raises an interesting theological question. Why did a supposedly beneficent Mother Gaia allow all this to happen before humans entered the fray? For if She did, then She had already preprogrammed her own destruction. Surely a truly beneficent Gaia would keep all the Earth trapped under ice so that no warming catastrophe could occur.
Proxies will always carry large uncertainties and any research based upon proxy evidence should be approached with extreme caution.
The best evidence (and admittedly the data quality has issues) is the thermometer instrument record post 1850 and CO2 measurements these past 150 years,
If we cannot detect a CO2/temperature signal in that data set, what expectation can realistically lie that a signal could be forthcoming in much more uncertain proxy data sets?
Of course, presently, no CO2/temperature signal can be detected in the instrument record. Even post Mauna Loa measurements coming on stream (ie end of the 1950s) there is no CO2/temperature signal: initially despite rising CO2 levels, temperatures drop through to late 1970s which is anti-correlation, then there is a period of warming which may track increases in CO2 emissions through to the late 1990s, then there is a period of stalled temperatures to date which are not tracking the increase in CO2 levels.
It is noteworthy that the best data we have, does not show any CO2/temperature signal notwithstanding numerous 'questionable' adjustments to the temperature record, at any rate, at least not without the addition of fudging via aerosol and/or assumed volcanic negative feedbacks, the addition of which is again highly questionable,
It is likely that within the next 10 years we will have a better impression as to whether a COI2/temperature signal truly exists in the modern instrument based data sets.
From a chemistry perspective, it makes much more sense that CO2 levels is a response to temperature since, we can readily see the necessary driver, ie., oceans absorb more CO2 when cooler and release more CO2 when they warm.
If CO2 leads temperatures then some mechanism has to be put forward as to what drove the CO2 increase/decrease. Presently, no one seems to be able to explain the reasons behind and the mechanisms for CO2 level changes. IF CO2 levels drive temperature as opposed to being a response to temperature.
I think this may be another shot-in-foot moment for climate science. They are so keen to show that CO2 drives temperature that they've introduced the corrollary bugbear - if CO2 can rise on its own without temperature rises in pre-industrial eras....then why is the current rise our fault?
By solving one inconvenient problem, they've introduced a 'but who designed the intelligent designer' type paradox.
Apr 5, 2012 at 10:04 AM | pesadia
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As regards your third point, you do not have to look further than the latest revised data set released by the UEA and the Met Office earlier this month to know that they are working on that point.
This new version shows a very slight warming these past 15 years.
"Where did the increase in CO2 come from?"
There must have been a lot of hominids trying to keep warm.. :-)
"Where did the increase in CO2 come from?"
Aren't they claiming some sort of bootstrap effect where CO2 got nudged by some northern hemisphere effect and this kicked off a whole train of events?
I'm still intrigued by this new narrative that seems to claim to show more representative world temperature than just relying on the Antarctic temps.
I wonder how they explain why the Antarctic temps against CO2 tracking closer than the new temp against same CO2 levels, when the Antarctic temps are the ones tending to precede CO2, is it coincidence? The Antarctic temp/co2 correlation seem to cry out that they are the real story and this new stuff seems more convoluted.
Leopard, we all know that the "real story" is the one that keeps the gravy train on the rails the longest.
I'm probably placing too much emphasis on my eyeball test though :)
In an essay linked to by ivan in Unthreaded yesterday (10:16PM) and recommended there by Jiminy Cricket today (8:18AM), I found this evocative description of one set of people for whom a climate crisis is a precious thing, to be treasured and protected:
'"misanthropic, anti-technology, anti-growth, dogmatic, purist, zealous, exclusive pastoralists"
Coined by an environmentalist for whom the penny has dropped about some of his fellows. http://www.theregister.co.uk/2012/04/04/kareiva_new_environmentalism_essay/
At his point the AGW community of academics have demonstrated so much corruption and bad faith, and most especially acceptance of corruption and bad faith, that there is no reason to accept this paper and its conclusions as anything more than deception.
I almost agree, hunter. But I'd moderate it to such papers should be treated with disdain and suspicion pending further investigation. A sorry state of affairs.
I'm almost at the point now where I feel like throwing my hands up and saying "OK, you win. Close down western economies. Don't come crying to me when you're starving because the university has been looted by starving proles, burnt and shut-down due to no public money to keep it going."
Because the recent petrol scare has re-inforced the old quote that we are only three meals away from anarchy. We're already having mass civil disturbance, and that was only the lust for flatscreen TVs and trainers. Imagine how savage it will get when people start starving. Academics have no intrinsic worth in the stone-age economy they seem so keen to return to. Except perhaps as fuel.
At face value, this appears to flatten one of the main sceptic arguements - the other being the Roman and Medieval Warm periods. But how did they occur?
I would prefer to hold judgement, as knee-jerk reactions to such papers, preferred by the warmists, do little to promote the sceptic/realist cause.
"Dr Shakun's team has now constructed a narrative to explain both what was happening on Antarctica and what was happening globally:
This starts with a subtle change in the Earth's orbit around the Sun known as a Milankovitch "wobble", which increases the amount of light reaching northern latitudes and triggers the collapse of the hemisphere's great ice sheets
This in turn produces vast amounts of fresh water that enter the North Atlantic to upset ocean circulation"
Am I being incredibly stupid? The above tells me that "increased light reaching the northern latitudes" actually means it is warmer and this warmth "triggers the collapse of the hemispheres great ice sheets"
which results in warmer oceans which release CO2?
So old stupid me reads that the earth gets warmer and then CO2 is released from the oceans and land as it greens?
The end of ice age warming starts in the Antarctic well before any effects in the North.
The same mechanism is responsible for the recent Arctic melt part of its 70 year cycle.
The Arctic is now freezing again.
"as knee-jerk reactions to such papers, preferred by the warmists, do little to promote the sceptic/realist cause"
I think declaring what does and doesn't promote the "sceptic/realist cause" does little to promote the sceptic/realist cause. ;)
Andrew
I find this quote very significant from p 30 of the Supplementary Information pdf (it is presently fully downloadable free)
'The results indicate Antarctic temperature led CO2 by a small amount throughout the deglaciation (Figure S25a). The global temperature stack, on the other hand, was synchronous with or lagged CO2, except at the onset of deglaciation when it led (Figure S25b).'
The key words being the last part of the last sentence.
Big Yin
"Except perhaps as fuel"
I was thinking food. I'm sure they've been nicely fattened up so far.
(Cue a burst of mock outrage from Zed anytime soon.)
Without access to the full article it's difficult to comment in detail, other than to say perhaps this is as close as we may get to an acknowledgement of serious problems with the existing "consensus". So is the science now "very settled"? I think not. As far as I can tell the criticisms of CO2 lagging temperature have so far mostly been waved away with if's and maybe's. Now someone claims to have found some proxies, in some parts of the world, that sometimes show the opposite for a short while. The evidence is described as "compelling" but I can't see why. Sorry, BBC, just because the piece is written by Jonathan Amos, not Richard Black, it doesn't make it any more compelling.
As Bishop Hill says, there are lots and lots of questions.
Can't say too much without the paper and I have better ways to spend $32.
But, don't they have to explain why Antarctic temperatures lagged? If it's simply because of its southern location, and they do refer to the north kicking the whole thing off and equatorial heat distribution being upset, then shouldn't NH and SH temperature proxies misalign? Their proxies are numerous and well distributed across the globe so they should be able to show individual hemisphere reconstructions, or even sub-hemisphere bands.
If Antarctica stands alone lagging the rest of the world we'd have to be skeptical of their reconstruction.
Hope to see Steve M do a post on it.
As Pharos mentions, “except at the onset of deglaciation” is one hell of a caveat. I guess they were hoping no-one would notice...
Scientific American, attempting to support this weird paper, came up with what I call the Magic Unicorn Theory of why the northern ice sheets melted.
""We know that the only thing changing in the Northern Hemisphere [20,000 years ago] were these orbital changes" that affect the amount of sunlight striking the far north, explains geologist Peter Clark of Oregon State University, who guided Shakun's research.
The melting in the north could have been triggered "because the ice sheets had reached such a size that they had become unstable and were ready to go."
This may also help explain the cyclical rise and fall of ice ages over hundreds of thousands of years."
http://www.scientificamerican.com/article.cfm?id=what-thawed-the-last-ice-age&page=2
Has anyone ever postulated the idea that the ice sheets were just too gosh darned big and just pooofff ... fell apart on their own?
"ancient tiny ocean animals"
I'm sure that's intended to make me think they were cute...
Unfortunately, I now have absolutely no faith in the integrity of climate research any more. Especially these EUREKA! papers.
Once a prominent climate science academic goes on record saying "We must get rid of the Medieval Warm Period", how can you???
But, don't they have to explain why Antarctic temperatures lagged?
But isn't the current theory that the poles heat up first when CO12 increases, hence the GISS data fiddle with the Arctic expalined as 'Well thats what we expect"
"Lots of questions occur:
we are comparing proxy-derived temperature readings to proxy-derived CO2 readings - presumably big uncertainties?
how were the proxies selected?
why the period selected - does the relationship hold outside this period?"
These questions lead to the intuitive conclusion that Nature is a publisher of works in science fiction.
Let's face it: papers such as these (like MBH, Steig et al etc) are produced to ostensibly knock down awkward issues for the "CO2 drives climate and we're all going to die" narrative.
The blogosphere will shortly be littered with claims that CO2 following T has been discredited and is a sceptical myth.
And this paper will no doubt slot nicely into AR5, as the deadline for acceptance is this August.
Er um
Being uneducated I hope this is not too stupid:
The ice core samples which have so far indicated that CO2 lagged temperature did not use a CO2 proxy, they used CO2 from bubbles locked in the ice. Why would anyone then place more reliance on a proxy record of CO2?
Erm... In the charts on the BBC article where are they getting the CO2 data from in both cases? It is identical. So they have either compared Antarctic and global temps to global CO2 or Antarctic and global temps to Antarctic CO2.
If I have understood the supplementary information they have based their CO2 data on data from the EPICA Dome C. If Antarctica warmed and the southern oceans became a net CO2 emitter this result is what you might expect isn't it? A warming southern region putting more CO2 into the air which mixes globally in a relative jiffy regardless of the global temperature trend.
I disown my last post and will now sit quietly in a darkened room for a while :(
Aren't the authors shooting themselves in the foot? Now they must claim that CO2 varies enormously independently of human activity or temperature. Either claim takes CAGW off the table as a serious consideration.
In the AGW belief system, as long as they can work back to the basic premise of humans are evil, everything is OK. If it means doing a 180 degree turn at high speed and no brakes to go opposite direction, that is OK as well.
Data, selection criteria, models, assumptions.
Amusing headline, if off topic...
http://order-order.com/2012/04/05/ken-is-the-14-5-former-climate-change-adviser-knocked-up-partial-figures/
If no one has said it I will: Where are the error bars? There was a day and age when this type of story did not get past the referees let alone into print without the authors being required to cite the numerical errors involved. The graphs had to diplay these in some way even if only as confidence limits. Shucks I had to do this in all my second year Phys Chem experiments in the early 60s or I got told to repeat my report from scratch and was marked down accordingly. Lay a dime to a dollar that the temp and CO2 vs time curves will show major overlap if this were done.
One other matter: have they smoothed their time series in their graphical presentation?