Babbage

Science and technology

Climate change

A record-making effort

Mar 31st 2011, 23:20 by O.M.

ON THURSDAY March 31st Richard Muller of Lawrence Berkeley Laboratory gave evidence to the energy and commerce committee of America’s House of Representatives on the surface temperature record. Without having yet bothered to check, Babbage can say with some certainty that this event will be much discussed in the blogosphere—as, oddly enough, it should be. 

Here’s the short version of the reason why: a new and methodologically interesting study, carried out by people some of whom might have been expected to take a somewhat sceptical view on the issue, seems essentially to have confirmed the results of earlier work on the rate at which the earth’s temperature is rising. This makes suggestions that this rise is an artefact of bad measurement, or indeed a conspiracy of climatologists, even less credible than they were before.

Now here’s the much longer version.

There are two topics which, more than any other, can be guaranteed to set off arguments between those convinced of the reality and importance of humanity’s impact on the climate and those not so convinced. One revolves around the question of how reliable, if at all, statements about average global temperatures before about 1500 AD are. This is the so-called “hockey stick” debate. The amount of computer processing power and data storage capacity devoted to endless online discussions of the hockey stick— the subject featured in a great deal of the brouhaha over the “climategate” e-mails—must, by now, have the carbon footprint of a fair-sized Canadian city, which of course would worry one side of the argument not a whit.

The second touchy topic is the instrumental record of the world’s temperature over the past 100 years or so. This is a more genuinely interesting subject, for two reasons. First: Consider a person who looks at all the non-hockey-stick evidence and arguments for thinking people are changing the climate (we won’t rehearse them now, but here’s a relevant article from The Economist last year). Imagine this person then saying “you know, that radiation balance and basic physics and ocean heat content and all the rest of that stuff looks pretty conclusive—but because I can’t say for sure whether it was warmer in 1388 than it was in 1988 or the other way round I’m going to ignore it all.” This would probably not be a person you would take very seriously. 

(It is because of this that the wiser sceptical voices in the hockey-stick debate do not claim that uncertainties over what, if anything, can reliably be said about mediaeval temperatures invalidate the scientific case for a strong and worrying human influence on climate. They say instead that there are a variety of statistical and other flaws in some of the reconstructions of mediaeval temperature, that some of the scientists responsible for some of these reconstructions have not behaved well, and that if that is typical of climate science then climate science in a whole is in a bad way. Thus the hockey stick becomes a sort of meta-, and indeed metastasising, argument.)

If, on the other hand, you imagine a person who has looked at all the other relevant material going on to say “You know, this is all very well—but there doesn’t seem to be any conclusive evidence that the world has actually been getting warmer in a significant or surprising way over the past decades,” you might well think hmm; if that’s the case then he has a point. Evidence that the world really is warming does seem pretty apposite to the whole issue. Being able to trust the records of what thermometers spread out over the world have actually measured and the procedures by which  those records are combined into a series of average global temperatures matter rather more than the hockey-stick. 

Another reason is that mediaeval data (from tree rings and the like) at issue in the hockey stick debate are necessarily sparse and patchy, and coming up with really robust answers to all the relevant questions on the basis of them may well prove impossible. The data on which the contemporary surface temperature record is based, though, is rich. There are a great many temperature records in archives around the world. If you can choose records that are demonstrably reliable and combine them in an appropriate way, you should be able to get a pretty solid answer. This thus seems like an argument that could conceivably end in agreement on an important issue. 

Indeed, most climate scientists would say that it already has. There are three different combinations of instrumental temperature records that seek to show average surface temperatures back to 1900 or earlier. Two are American, with one produced by the National Oceanic and Atmospheric Administration (NOAA) and one by NASA; the other one is British, with data from the Met Office and the University of East Anglia’s Climatic Research Unit (which was the epicentre of climategate). They used many of the same raw data, but the ways in which they adjust them to remove presumed artefacts and then combine them differ. Yet they come up with very similar answers, and when they publish their figures with error estimates they come within each others’ margins of error. The fact that three different groups agree in this way would normally seem to justify relying on the result.

But there are many ways in which climate science is not normal, one of which is that it matters a great deal with respect to some very expensive policy decisions. Various criticisms of the methodology and probity of the temperature records have been made, though much more often in the blogosphere than in the scientific literature. Erring on the side of extra caution is not a bad idea, and various efforts are underway to develop, corroborate and better to underpin the work on temperature records that has been done to date. One such effort is the Berkeley Earth Surface Temperature programme, which Dr Muller heads. 

 

Fearless physicists

Dr Muller is an astrophysicist, not a climate scientist, and was indeed seen by some as being a bit of a sceptic, in the unfortunate negative usage of the word. He is strongly spoken in his criticism of some of the behaviour revealed in the climategate e-mails, and talks admiringly of some of the amateur or non-credentialed scientists who have mounted critiques of published climate science. 

He also has a sort of intellectual fearlessness most often seen in physicists; when applied to other fields of endeavour this can look uncannily like a form of arrogance, perhaps because that is often what it is. The initials of the Berkeley Earth Surface Temperature project could be read in this light, and indeed they were so interpreted by some climate scientists, who got rather bit peeved at the idea that interlopers should presume to claim a priori they were the BEST. Any arrogance they may be prone to, though, doesn’t invalidate the fearless physicists’ insights. Dr Muller’s beloved mentor, Luis Alvarez, was quite right when he and his son argued that the death of the dinosaurs had less to do with the environmental or evolutionary challenges palaeontologists concentrated on and more to do with the damn great meteorite or comet impact for which Alvarez père et fils had just found dramatic and unexpected evidence. On the other hand Dr Muller’s subsequent variation on the Alvarez's now broadly accepted contribution, which led to an unsuccessful search for a distant planet that might be directing killer comets at the earth on a regular basis, has as yet come to naught.

The Berkeley approach seems based on the idea that coming out of physics, not climate science, was going to be a strength not a weakness. Rather than look at carefully (and similarly) selected subsets of the data it would look at everything available, just as astrophysicists frequently seek to survey the whole sky. Rather than using the judgement of climate scientists to make sense of the data records and what needed to be done to them, it would use well designed computer algorithms. Put together under the aegis of Novim, a non-profit group that runs environmental studies, the team gathered up a bit over half a million dollars—including $100,000 from a fund set up by Bill Gates and $150,000 from the Koch foundation, whose animosity towards action on climate change made the Berkeley project look yet more suspicious to some climate-change activists—and got to work. There was also support from the Department of Energy’s Lawrence Berkeley Lab, where Dr Muller and some of his team work. It is probably fair to assume that Steve Koonin, an undersecretary of state at the energy department with whom Dr Muller has served as one of the “Jasons”, a group of particularly intellectually fearless scientists which provides blue-sky and sometimes far-out advice to the defence department, and who has also produced a report for Novim, had an unofficial eye on what was going on. 

Dr Muller’s testimony was not exactly the unveiling of his team’s first results—you can find him saying much the same in a seminar on the web— but it was a particularly high-level early outing. It was also a strikingly robust defence of the record as others have interpreted it. Calling the three extant groups “excellent”, Dr Muller described preliminary work by the Berkeley team on the overall magnitude and course of recent warming that backed them up. Instead of picking a relatively small number of weather stations to look at, this work simply took 2% of all the records the Berkeley group has access to at random. The results look very like what the other three teams have seen. The Berkeley team says that it has run such 2% experiments a number of times now, and the results are robust. The earth has warmed by about 0.7°C since 1957, just as the other teams claimed. Adjustments made to the data on a site-by-site basis which have had some suspicious sceptics hopping mad seem to have made no appreciable difference.

 

The Watts and wherefores

Dr Muller also, more controversially, reported on results that pertain to a specific point made by climate sceptics; that the temperature record is contaminated because many of the stations used to compile it are in inappropriately located. This idea is particularly associated with Anthony Watts, a former television weatherman who runs an extremely popular website catering largely to a climate-sceptic crowd. Mr Watts has led an impressive crowdsourcing movement devoted to checking out the meteorological stations that generate climate data in America. This has found that a really surprising number of the instruments concerned are not sited in the way that they should be, being inappropriately close to buildings, tarmac and other things that could cause problems.

A compendium of Mr Watts’s concerns was published early last year by the Science and Public Policy Insitute, which specialises in airing doubts about climate science and policy, under the title “Surface Temperature Records: Policy Driven Deception?” Dr Muller’s answer to that question in front of Congress was pretty clearly no. The Berkeley team compared the data from the American sites Mr Watts thought were worst situated and the sites he thought best. It found no statistically significant difference in the trends measured in the two different categories, though the warming trend in the better sites is slightly stronger. 

This analysis echoes one carried out last year by scientists at NOAA, which when looking at a subset of Mr Watts’s data found much the same thing. The Berkeley team’s result, though, is perhaps more striking, in that Mr Watts had made all his data available to Mr Muller and his colleagues, a step he seems now rather to regret. 

Impressed by the Berkeley set up, Mr Watts wrote in a post published March 6th:

I’m prepared to accept whatever result they produce, even if it proves my premise wrong. I’m taking this bold step because the method has promise. So let’s not pay attention to the little yippers who want to tear it down before they even see the results. I haven’t seen the global result, nobody has, not even the home team, but the method isn’t the madness that we’ve seen from NOAA, NCDC, GISS, and CRU, and, there aren’t any monetary strings attached to the result that I can tell. If the project was terminated tomorrow, nobody loses jobs, no large government programs get shut down, and no dependent programs crash either. That lack of strings attached to funding, plus the broad mix of people involved especially those who have previous experience in handling large data sets gives me greater confidence in the result being closer to a bona fide ground truth than anything we’ve seen yet.

Responding to Dr Muller’s testimony, Mr Watts e-mailed that when he shared his data he “was expecting a study done by peer review, months out, not a job rushed in three weeks for political theater in the House of Representatives.” Though some of his results and conclusions were published in “Policy Driven Deception?” he has since worked on a peer-reviewed publication, sensible to the accusation often levelled at his blog that such publication is the way to do proper science. That this is not what the Berkeley team did, choosing instead to present preliminary results to Congress, has upset him, and he has asked to have a statement of his own read into the congressional record. The Berkeley team, for its part, argues that while it would rather publish in a peer-reviewed journal before discussing its results, and has “begun the submission process to do this”, an invitation to address the committee deserved what the team saw as the best available answers. 

Mr Watts’s paper, on which he has a number of co-authors including climate scientist Roger Pielke Sr, is now said to be close to the end of its road towards publication. It claims to find that there is indeed a difference between the good and bad sites: though they may provide indistinguishable results for trends in average temperature, they differ when you look at trends in minimum and maximum temperatures, which has implications for the diurnal temperature range. It is not clear what the climatological significance of this might be, and it is always worth bearing in mind that these data only apply to stations in America, which is a fairly small part of the planet. 

Overall, the takeaway from Dr Muller’s presentation of his team’s data is that, in the words of one climate scientist, a “Koch-brothers-funded study confirms the previous temperature reconstructions.” Dr Muller says the team will now be looking into a number of other effects, including the bias that the “urban heat island” effect—cities are warmer than surrounding countryside—might have. The question of good versus bad location is linked to this (a good site can become bad as a city sprawls over it) and so is the issue of which records you choose to use (long records, preferred by earlier reconstructions, may be more prone to changing urbanisation around them). But there is more to the problem, and Dr Muller hopes to look into it further, as well as into issues that might arise from the times of day at which observations are made, stations moving from one place to another, and changes in the instrumentation used. 

The Berkeley work, especially after it is published and disseminated in full, may increase the acceptance of the reality of global warming among people who have so far managed to maintain a comforting and sometimes self-serving feeling that maybe the people who deny that anything is going on are actually right. It doesn’t in itself show how much of the warming is due to human activity. Dr Muller, in a somewhat cavalier way, chose to suggest that about half of what had been seen since 1900 was. Other scientists would put the proportion higher. 

Nor does it say how much warming is yet to come. Carbon dioxide and other widespread gases can warm the earth, but dust, smog, sulphate particles and other things can cool it. There is no very reliable record of how these cooling factors changed over the 20th century, but they must have played a role. So you can’t simply look at temperature changes over the 20th century, and scale them up according to the amount of carbon dioxide you expect, to find out what will happen next. Though Dr Muller, in his testimony, seems to differ on this—as might perhaps be expected for someone proud of a new contribution to the field, and hoping to make more—most climate scientists do not believe that further improvements in the accuracy of the average temperature record over the twentieth century will add greatly to their ability to predict the magnitude or timing of the changes to come.

But broader agreement that the temperature has indeed risen quite steeply over the past century is nevertheless a thing worth having. If the Berkeley team can help provide it, that is all to the good. 

Comment policy: anyone who thinks this post was telling the truth about the fair-sized Canadian city mentioned near the beginning should please refrain from commenting. 

 

Readers' comments

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Rob S

@esoteric
Exactly what evidence is there, aside from the coincidence of CO2 and a warming trend, that one caused the other? My understanding from reading the literature is that analysis tell us that the relationship, if it exists, is an indirect one, as the direct effect of CO2 is not sufficient to account for the warming trend.

In other words, the proof that doubling of CO2 causes a 3C change is essentially a circular argument. We assume, based on the observation of the coincidence, that CO2 does cause global warming, albeit by some as yet unidentified indirect effect (perhaps involving changes in water levels). If our assumption is correct, then a fitting of the data gives us this relationship.

I find this argument unappealing - as unappealing as the argument based on appalling to authority.

Djon

orlin_2,

We aren't worried about the planet. The planet will be fine no matter what we do. It's the welfare of the several billion humans living on the planet and, for the more environmentally minded, of many of the other living creatures on the planet. A conspicuous feature of the "dramatic, and rapid global thermal events that have affected the earth throughout the planet's history" you refer to is that they predate, among other things, agriculture, which there are rather good reasons to believe will be negatively affected by the warming scientists currently anticipate over the remainder of this century.

orlin_2

Perspective is badly missing from this debate.
Yes, given certain arbitrary start- and end-points, worldwide temperature measurements can be taken to show a warming trend on periods up to 130-odd years or so (the latter of which are only now reliable thanks to the new publication cited by this report). What this blog post grossly fails to mention, and on which note I am astonished and severely disappointed in the Economist, is that the overall trend taken at longer timescales (e.g. 4 million to present, 25,000 to present)...is one of cooling. The recent change is entirely within the normal oscillation that belongs in the realm of natural climate fluctuation.
On model calculations, the sum total of $34 billion of counter-warming expenditure per year until 2100 in the EU will amount to a net achievement of 0.06 degrees of mitigation of warming by 2100.
Can we all please look at this issue in the context of much more dramatic, and rapid global thermal events that have affected the earth throughout the planet's history.

Mervyn Sullivan

Why would anyone trust those who maintain the surface temperature record. It is beyond doubt that the surface temperature data has been manipulated to an extent that could be deemed fraudulent. New Zealand is a classic example.

I urge readers to look at the more accurate, meaningful and relevant temperature data - the UAH Satellite-Based temperature of the Global Lower Atmosphere, and observe how the recent temperature compares to 1988 when NASA's Dr James Hansen gave his alarming testimony about how rising Co2 in the atmosphere would cause runaway global warming:

http://www.drroyspencer.com/latest-global-temperatures/

1988... 2011. Can you see where temperature was and where temperature now is? Exactly! There has been no discernible increase in temperature despite rising Co2 levels in the atmosphere.

Based on this evidence, I'll leave it to readers to make up their minds about whether rising Co2 emissions from human activity is causing catastrophic global warming, as promoted by the IPCC and its 'flock of believers'!

nickbrockett

@ blue asgard
thank you for your comment.....i am a layman....i can believe that manmade releases of co2 are responsible for higher levels in the atmosphere...but in these pages and others i see only the negative effects argued...no positive...leary of such things...the public assumption is that climate change is 'bad'...most of the western governments are broke....and all the solutions involve giving feckless politicians control of large percentage of the worlds wealth...this has never worked....answers i dont have....but i do have interest in rational discussion. thanks again.
most mammals have lice specific to that species.humans have two...hair lice & body [clothes] lice. some research suggest they diverged about the time of the toba eruption.

Sense Seeker

Am I confusing you, Lucrecius? Let me alleviate your puzzlement a bit.

I never wrote I am Australian. I do live in Australia. I am not religious. I am a scientist (which in my mind doesn't combine well with religion, but that's another discussion), though my field has little to do with climatology. This background does help me to judge arguments and gave me a training in writing clearly.

I am not paid for my contribution to the discussions here. The only potential conflict of interest I can think of is that I have part of my savings in an ethical investment fund, which also invests in renewable energy sources. But mainly I have children and I would like them (and everybody else) to live on a healthy planet. If you are looking for conspiracies to deceive you, you will have more success when you look at the other side (i.e., the denialist side).

The reason for focusing on climate change is that I think it is really a important issue and I see the way vested interests are misrepresenting the science in the public debate, often with outright lies, repeated long after they have been proven false. It's the distortion of facts that I mostly react to. I have opinions on other issues too, but tend to be more cautious with those.

Does that help?

Lucrecius

Sense Seeker,

unfortunately you no longer make sense. Based on your comments in many climate related articles only (I cannot find other areas of interest), your style, involving "proud to be a European", "as an Australian", "God help us"...do I need to go on...does strongly indicate that you are a) not a scientist b)a professional "propagandist" c)using extensive political rhetoric d)not sure where you live d)believing in religion.

Seneca once stated that religion is believed by the common people, not believed by the wise and regarded as useful by the rulers.
Please replace religion by AGW and voila...

I don`t think you belong to the group of common people but then maybe you are useful to the rulers...

blue asgard

@nickbrockett

Toba blew up 69-70,000 years ago, you can see the 2 degree drop in global temperatures for 2000 years after that in the raw ice record (resolution 1000 years).

Mount Taipo blew up 23,000 years ago (not 24,000 years ago) you can see a huge soliton wave in an otherwise quiescent high frequency 1000-year wide waveband from the ice record running from 23,000 years ago for about 2,000 years. Taipo being a lot nearer to Antarctica than Toba you'd expect to see a bigger signature from a similarly monstrous eruption. It looks like another 2 degree cooling in the unfiltered record but it's all over the place in that time period, so hard to make out.

So the essence of your point is you will get cooling with monster volcano eruptions, but the authors of the paper I quoted say that carbon soot stays in the stratosphere 5 times longer than even the finest volcanic ash. However Toba style diebacks (and the human race was almost wiped out by Toba, big bottleneck event) are more typical of letting off some 3,000 nukes roughly what the US and Soviets said they'd come down to in the latest START. Not exactly reassuring.

However the Human flea finally evolved some 67,000 years ago (again hard to be exact, you have to count mutations in the flea genome and assume they are regular). Must have found all those furs the humans suddenly started wearing really cosy placed to be, complete with readily available blood supply to feed off. It's an ill wind which blows nobody any good.

There is always difficulty in dating these ancient eruptions. Even modern Thera has been put back 100 years by recent research and uprated to Level 7 at the same time.

Now I'm out of here.

Sense Seeker

@exoteric (yes, I know you've left)

Well, consider it akin to health claims, which are only allowed to be made if they have been scientifically confirmed to be true (or rigorously tested and not refuted, for the Popperians). It is not sufficient if the manufacturer claims to have done the calculations in-house.

nickbrockett

@blue asgard
regarding nuclear winter...you might look at the toba eruption [sumatra] 74,000 years ago....it put a kink in our gene pool...and buried india under 5 feet of ash.

nickbrockett

@exoteric
thank you...your the first. small increases in co2 greatly reduce water loss in plants...i think north africa will bloom again.

exoteric

@ Sense Seeker

Immoral? Maybe slightly misguided but I am not sure about immoral. I feel a bit like good cop bad cop here. I think I will leave the the rest to you. I am out of here.

Sense Seeker

@blue asgard,

I admire your knowledge of the technicalities of climate change, and the fact that you can perform analyses that must really be quite complex. Yet I also notice that your position irritates me enormously and I had to think why that is. I think I know now. I consider your position on whether or not to submit to peer-review *immoral*.

You see, here we have a case where the overwhelming scientific evidence that the world must take action, action that is painful for many. Along comes blue asgard who writes that he has done analyses that show the science is wrong and no action is required. This creates doubt, and makes it easier for the ones who profit from the status quo to say the science cannot be trusted.

You say you are not interested in weighing in on the debate and only want to know things for yourself. But that is evidently not true: you post on this blog. If you were really only out to convince yourself, you would keep your findings to yourself. Your position is inconsistent. You hint that you have results that contradict mainstream science, but refuse to have them examined by fellow experts. You are blocking the way. You can forever stick with your results and nobody can refute them to put the matter to bed, nor confirm them and open up new insights.

All the talk about cargo cult is simply a smokescreen, though you may have convinced yourself. Either you are afraid someone may prove you wrong (which would make it difficult for you to consider yourself an unrecognised Galileo), or it is calculation and you are just out there to create doubt and stall action. Neither is excusable in my view.

So the consistent line of action would be to submit or shut up.

exoteric

@blue asgard

On your recommendation I did reread Feynman’s piece on Cargo Cult Science and it is very funny (especially the bit about the pituitary). I doubt my friends in psychology would agree though. I too wish that everyone involved in the discussion of climate change had the kind of integrity he describes. While I feel that climate science in general does not fall into the category of "Cargo Cult Science", much of the discussion about it does lack integrity. Unfortunately the debate often becomes political, with all the shouting that entails, rather than scientific.

exoteric

@blue asgard

I think there are fewer de facto assumptions in suggesting greenhouse gases are responsible for warming than any other possibility. I am afraid it by far fits best with available data and theory.

I guess I am disappointed that people do not trust scientists more. Climate science is complex and it is difficult to understand many of the subtleties without years of study. It seems that many people can be easily swayed by others with an agenda but little scientific background. It is one of the problems in a democracy. We can not all be experts in all areas yet we all need to make decisions in areas we are not able to understand. For me I tend to trust experts but others seem to think that everyone else is out to ruin their lives. I suspect that people skeptical of science are more prone to "group think" than scientists.

Anyway - although I do try my best to inform people about climate science when I can, my time for discussion is very limited. You sound like you are involved in many things. Good luck in your analysis and if you do find something interesting - try publishing it. You never know. Once in a while things make it through the gauntlet.

blue asgard

@exoteric

I am happy to debate the issues with you as you seem quite rational about it all. If you are familiar with previous posts on this topic to this site this has not been the norm.

Ler me be clear, I am not defending any particular point of view here, rather I'm much more interested in a quite different topic, namely the consequences of quite low level nuclear war. The protagonists of the concept of a nuclear winter (originally in the 1980s) have turned to modern climate models to try to figure out what would happen. Here the issue isn't so much CO2 but particulate carbon. Outside Wikipedia there's a good article in Scientific American on this (Robock A & Toon O. B. "Local Nuclear War, Global Suffering" Sci. Am. January 2010 pp 74-81). The results they quote seem to require far too small thresholds, for example if 20 KT fission bombs were used then 2 MT would plunge the world into a dieback of perhaps 1 billion people. yet 2 MT and even 50 MT bombs have been tested without anything remotely like a nuclear winter.

It would be very nice from a political point of view if these guys were right. One could, for example get everyone to agree that their modelling was realistic by letting other countries use the models themselves and verify them. That might well include a software audit to make sure the modelling system was really doing what it was supposed to be doing, in short wringing all possibility of dissent from the truth of the results by everyone who might be affected by nuclear weapons reduction treaties. Arguably this should have been done for climate change BTW. Incidentally Gorbachev himself said that the earlier (1985) work on nuclear winters was verified by his own people and he then realised that nuclear arsenals on the scale they had were futile. This was the impetus to various START agreements, the last of which was only ratified by congress this year! So this new result, if true, could be the beginning of a further ratcheting down of nuclear arsenals.

If true.

The key is clearly in the modelling system which de facto makes many assumptions - just like yours on CO2 BTW - about how climate behaves. So the obvious way to approach the issue is to try to avoid those assumptions and peel back the claims about behaviour by other means. Milankovitch etc. cycles seem to be a good starting point. I was actually researching a book about politics, which included foreign politics, and is still a priority, hence the reluctance to leap into a side-battle with all the promise of being all-consuming. Nuclear war/winter is just a part of the wider scenario but it is apparent that the whole climate change debate is consumed by politics also, moreover in ways which I have gained insight on through more research which is of no interest here but has equal opportunities for another controversial maelstrom. It seems that the politics of climate change have done immense harm to the science of climate change and the language of debate on the subject is full of discussions of politician’s concepts – majorities, certitude and political enemies – and behaviours – fanaticism, contrarianism and incorrigibility. And science is being –has been - corrupted by it. As you point out the role of contrarian is a good one in science, if played successfully but that means not just publishing against the tide but also getting a movement going. There is no chance of getting anywhere otherwise. And, bluntly, life is too short.

The problem arose when I did a preliminary calculation which showed that I could reproduce the Eemian with Milankovitch+ cycles alone and then also the Holocene up to to-day! This was complete with a late jump up to 1.3 degrees in the next millennium, starting probably 1- 200 years ago. Then I started to really question the climate models because no-one was talking Milankovitch. Then there are more questions. What happened to the Neolithic (sub)pluvial? The previous one, the Mousterian, lasted 20,000 years but the Neolithic only 4,000. Evidence that these things are features of a warming planet are beginning to come in (Sacks, J., Myhrvold C. ‘A Shifting Band of Rain’ Sci. Am. March 2011 pp 52-57) and of course the 11K cycle, the one I’m fingering, insolates the tropics. Does this show up in the climate models? Expect more rain and a lot more plant growth and CO2 sinks. These are the dangers of assuming normally stable conditions which are not supported by the Milankovitch cycles BTW, only coincidentally so far, in the Holocene.

What price cargo cult science now? I do recommend reading Feynman’s piece, if you haven’t. He’s saying cargo cult science is unsafe science. You don’t want to be anywhere near there. And I’m just raising questions which look like needing answers.

exoteric

@blue asgard

It is fine to explore the science on your own and not publish but as Sense seeker suggested you may not have the same authority (when trying to convince others) as someone who publishes. There certainly is inertia in science and bucking the trend can make it harder to get published, however, the reward is often greater in the end - if you are right. The reason is simple, contrary science needs to be scrutinized more because its consequences are greater. If you want to call this cargo cult science than so be it. I think it is appropriate. If you can show that the work stands up to scrutiny it will get published. The reason a lot of contrarian views do not get published is not because of group think, it is that many do not stand up to scrutiny. After all, all contrarian views can't be right either - there are too many!

Sense Seeker is also right about inertia in the system. Estimates from the IPCC AR4 models suggest that there is about another 0.6C of warming to come even if we held CO2 at current levels. This is called "climate commitment". This happens because the Earth's oceans are not yet in radiative balance with the current levels of CO2. Once the ocean stops warming, we will achieve our maximum surface temperature but this can take hundreds of years.

As for doing these calculations myself - unfortunately there are many interesting questions in climate science and I choose to pursue the ones that would appear to be most fruitful. I am afraid you have not convinced me that looking in ice cores for harmonics of Milankovitch cycles in order to explain current warming is one of them. I am happy for you to explore it though. Only heed your own advice and keep an open mind to other, perhaps more well supported, possible explanations.

As for Kirchner and how CO2 relates to temperature, I am afraid this is not a linear relationship but rather closer to logarithmic. It some ways this is fortunate because as we add more carbon to the atmosphere the radiative forcing, per amount of carbon added, actually goes down. Unfortunately nowhere close to zero! A simple but reasonable approximation you can use to calculate radiative forcing from CO2 (in W/m2) is: RF = 5.35*ln(CO2/CO2ref). You can calculate the radiative forcing from CO2 at the LGM compared to preindustrial and it is about 5.35*ln(180/280) = -2.36 W/m2. If we assume that temperature is linearly related to radiative forcing (which is also not true but more so than for CO2) and you assume that the LGM was about 4C colder, then one might think that current CO2 would lead to a equilibrium temperature of about 5.35*ln(390/280)*4/2.36 = 3. C higher than preindustrial. This is still too high by about a degree or so but this is because there were feedbacks at the LGM that enhanced the cooling (such large ice sheets reflecting a lot of sunlight back to space). The system is much more complex than simple linear relationships between CO2 and climate - that is why we spend so much effort developing models!

blue asgard

@sense seeker

What if you don't care about counting, as you so put it? What if the point is to just get an idea of when people are talking rubbish? The area of climate change is full of argument and counter argument from people with closed minds and there are lots of papers out there busily contradicting each other. In such a situation you can spend all day quoting this expert or that and indeed be totally misled by one camp or another. In the end you are a voter and you can vote down a rubbish policy. But is it?

There is one way, do it yourself. Do the calculation. Then you'll get a genuine insight, one you can believe. After that, well, you might publish, see your name in lights. But meantime you'll have the certainty of what you find out for yourself.

You and I have crossed swords before. Can you really do the necessary calculation? Do you know how? If not, how can you possibly evaluate what anyone is saying in this debate, although 'debate' implies open minds when I see none?

An unpublished contradictory result is just that. It is a sign that maybe skepticism is in order. A responsible scientist won't wait for the publication - scientists talk among themselves after all - but will endeavour to produce the contradictory result for himself. Anything else, as Richard Feynman suggests in his inaugural address at Caltech in 1974 (republished in Engineering and Science), is cargo cult science. And it strikes me that an awful lot of what passes for climate science is cargo cult science the way he defines it. But what is worse, and what causes these so heated debates in postings like this, is cargo cult worship, the religious adoption of the 'findings' of cargo cult science by people who cannot actually work it through for themselves.

As Theodore Sturgeon says 90% of everything is rubbish. Doing it yourself is a rubbish filter, apparently essential here.

Sense Seeker

@blue asgard,

Well, sorry if I sound skeptic, but a present-day Galileo, albeit one who doesn't try to publish his results, who would have thought... If you are serious, you publish or you don't count. Simple as that, no excuses. It just needs that quality check, and if it is good, it needs to be publicised widely.

That said, I was wondering if current CO2 levels would fit much higher temperatures than observed now, could that simply point to the inertia in the system - in other words, unless the CO2 is cleared unexpectedly fast, we have an awful lot of heating still coming even at present CO2 levels?

blue asgard

@exoteric

Perhaps you didn't look at the last two pages of Kirchner's paper carefully enough. He gives two graphs, one for CO2 concentrations, one for methane. Each graph shows the paleohistorical correlation between global temperatures and gas concentrations in the atmosphere. The easier one to extrapolate is the CO2 graph. All the paleohistorical temperatures correlate pretty well with CO2 concentration, all except one, the present concentration, which is wildly out by comparison. In order to have the present concentration correlate with the rest you need to raise that point until it corresponds to a point 8 degrees warmer than it is now. Then the point will be on the regression line. There is no evidence that the regression is anything but linear. The situation is much more extreme for methane.

Kirchner offers some explanations as to why this might be. One is that we will get there eventually, another that there are feedback processes which will clear the CO2. Either way the evidence that the present level of raised CO2 is consistent with present temperatures simply isn't there.

The point of all this is that there are explanations as to why temperatures are/might be rising which are nothing to do with CO2 levels. I take it that you accept that the temperature rises and falls which began and ended the last interglacial were natural, presumably caused by the Milankovitch cycles and, since you are so reluctant to agree that the tropical insolation cycles are Milankovitchian (the same cause but not the same place), the tropical insolation patterns as well. Maybe there are other natural cycles at work if you don't believe this. If so, they will all be captured in the ice cores.

Now the EPICA data form 1,000 year averages so it is impossible to get cycles less than 1,000 years long out of them (Nyquist limit), so everything I was saying about shorter cycles was just to say that they are there in temperature records but not in the ice record which is what I've been working on. None of them are anything like as large-amplitude as any of the Milankovitch+ cycles I see in the record. I would discount anything with an amplitude of these than ±0.1 degree, frankly. When figuring out exact reconstructions of past interglacials they all have to be counted but for that you have to go back over the record looking for cycles of up to 125,000 years in 1,000 years bands. Correct reconstruction shows you are not distorting the values in the IK wavelength bands.

Every now and then I get snide remarks about actually getting my hands dirty and digging out results for myself. Why don't I publish and get it into a peer -reviewed journal, they ask? The very idea that it’s only valid if blessed by the priesthood is anathema to a practicing scientist. ‘Cargo Cult Science’ Feynman called it. If it doesn’t make sense, figure it out for yourself. Like I said, I need to take Rial's insights on board, if only to confirm the accuracy of my present results, a necessary precaution in a potentially hostile refereeing climate. So, OK, you can wait 3 or 4 years for the wrangling to subside, maybe never see it if it is suppressed like so many others. Meantime people are rushing to conclusions which seem to me quite unjustified from where I'm standing. And why are you so desperate to blame it all on CO2 when there is a clear counter-argument which suggests otherwise? Are you another cargo cultist? According to Popper a scientist should be skeptical until convinced of any particular position and even then be open to falsification. I offer the evidence for skepticism, not conviction.

But you can do what I've done. You, too, can take the EPICA data and slice it yourself into 1KY bands and see the cycles and their sidebands. By then matching the cycles and extrapolating them forward you too can see the consequences of a rapid rise in temperature right now. No CO2, just projection from history, and you don't need to wait 4+ years to hear it. I'd recommend using MATLAB, especially for the Bessel functions. You can use a spreadsheet but it'll probably have a hernia, and it's weeks of grinding work. You might like to average the last 5 complete interglacials (align them on their optima) which will show you the two dominant cycles driving the temperatures, one of which is the 11K which is starting (has started again) now. You should also check that you can reproduce the Eemian from your slices. Once those results start coming in then your confidence will increase enormously. After all, Galileo had seen the moons of Jupiter and the phases of Venus even though nearly everyone disagreed with his conclusions. 'And yet it moves' he is supposed to have said even after recanting. And it was a heresy trial.

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In this blog, our correspondents report on the intersections between science, technology, culture and policy. The blog takes its name from Charles Babbage, a Victorian mathematician and engineer who designed a mechanical computer.

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