Category Archives: IPCC

The New Hockey Stick

First of all, please accept my apologies for not posting for so long. I have been writing a paper based on some research, and have been working 7 day weeks on it for a long period. It is a challenging piece of work, with some results which undermine a body of theory. In order to get it published I have had to be more thorough, and go into depth that would not normally be required, and still it will be a fight to get it published. This is the nature of challenging the orthodoxy.

On the other hand, if you write something that is in line with the orthodoxy it is relatively easy to publish, even if the standard of the work is not very impressive. This brings me to the subject of this post, which is the Marcott et al (2013) paper, with the abstract as follows:

Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time. Here we provide a broader perspective by reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago. This cooling is largely associated with ~2°C change in the North Atlantic. Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history. Intergovernmental Panel on Climate Change model projections for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse gas emission scenarios.

I typed in the word ‘Marcott’ into Google News search, and the first headline that greeted me said ‘We’re Screwed: 11,000 Years’ Worth of Climate Data Prove It’. I don’t think it is possible to be more ‘alarmist’ than this. The article is found in the Atlantic, and the article lifts the following diagram from the Marcott et al paper:

marcott-A-1000.jpg

The article goes on to say that:

Back in 1999 Penn State climate scientist Michael Mann released the climate change movement’s most potent symbol: The “hockey stick,” a line graph of global temperature over the last 1,500 years that shows an unmistakable, massive uptick in the twentieth century when humans began to dump large amounts of greenhouse gases into the atmosphere. It’s among the most compelling bits of proof out there that human beings are behind global warming, and as such has become a target on Mann’s back for climate denialists looking to draw a bead on scientists. [emphasis added]

The article goes on to propose that the Marcott et al paper vindicates Michael Mann’s long discredited hockey stick chart. The hockey stick chart of Mann has always been a key plank of the alarmist argument, as it is the ‘evidence’ that the warming that took place in the 20th century was unprecedented; it was the ‘smoking gun’. In particular, it removed two key elements from the temperature record, which were the medieval warm period, and the little ice age which followed in the wake of the medieval warm period. In a post in Climate etc., Rud Istvan explains it thus:

The MWP has progressively ‘disappeared’ over the course of  the IPCC reports. FAR and SAR showed it to have been much warmer than the present—and nothing to do with CO2. By TAR the MWP was gone, leading to the hockey stick controversy and climategate.

While the MWP did not completely disappear in this new paper, it turned into a <0.1°C blip colder than 1961- 1990. This is quite curious. The MWP was not a blip for the entire northern hemisphere, as illustrated by this figure adapted from a 2010 paper by Ljungvist.

The diagram referenced is given below:

Ljungqvist 2010

As is evident in the Atlantic article, the media bandwagon has started rolling on the findings of Marcott et al, but the problems are already starting to appear. The data used for the paper was made available (which is certainly a positive), but this has allowed others to look closely at the findings. For example, at Suyts blog, Hank ‘discovered that only nine of the 73 proxies contained data that extended to 1950. Of those nine, only two contained data that extended to 2000′ [and] Starting at 1,500 before present (BP), I graphed the nine proxy datasets. And here’s what I got:’

clip_image004

The hockey stick is not apparent, and this is why:

This new 73 proxy study has alarmists convinced that this is an independent verification and vindication of Mann’s hockey stick. It isn’t. The hockey stick blade at the end of the reconstruction is resulting from an adjustment of the proxy data to agree with Mann’s treemometer study. That, or it is an outright splice of Mann’s data directly.

Inevitably, Steve McIntyre, who played a key role in discrediting the Mann hockey stick, has weighed in. In what Bishop Hill calls an ‘astonishing’ post, McIntrye observes that:

Marcott, Shakun, Clark and Mix did not use the published dates for ocean cores, instead substituting their own dates. The validity of Marcott-Shakun re-dating will be discussed below, but first, to show that the re-dating “matters” (TM-climate science), here is a graph showing reconstructions using alkenones (31 of 73 proxies) in Marcott style, comparing the results with published dates (red) to results with Marcott-Shakun dates (black). As you see, there is a persistent decline in the alkenone reconstruction in the 20th century using published dates, but a 20th century increase using Marcott-Shakun dates. (It is taking all my will power not to make an obvious comment at this point.)

The graph comparing the two is given below:

alkenone-comparison

There is plenty more to the critical analysis of the work, for example the absence of the hockey stick in Marcott’s thesis, or the lack of resolution of the proxy data. As a headline from Wattsupwiththat put it, ‘Tick, tick, tick – how long will the new Marcott et al hockey stick survive?‘ My purpose is not to review the many gaping holes appearing in the Marcott et al paper but to consider why this paper has appeared now. The first point to note is that the data was released with the paper. This is important, as it is an admission that hiding data is no longer acceptable practice. However, this presents a problem for alarmists who present questionable work; they are damned if they do not release the data and damned if they do.

As the data comes under increasing scrutiny, it is becoming very apparent that this paper is extremely problematic, and that the conclusions trumpeted by alarmist media sit upon extremely shonky foundations. The authors, unless very naïve, must have been aware that there paper would not hold up to close scrutiny. However, in having a paper accepted in the peer reviewed literature, they have managed to potentially reinstate the hockey stick – and this might now appear in the next IPCC report. In publishing this work, the authors may have sacrificed their credibility to some degree, but in doing so, they have gained membership of the faction in climate science that dominates the literature (see here for why this matters).

The publication of this paper has been important for the alarmist position as the science of climate change, and the alarmist position, is bumping up against the harsh wall of reality. In particular, the models that are so important in the alarmist case are having trouble with the recent stall in warming; they cannot explain it. There is a very good summary of the problems created by the stall in a report issued by the Global Warming Policy Foundation, written by David Whitehouse. This is from the executive summary, but I recommend reading the whole report (about an hour to read):

The standstill observation was first made in 2006; the global annual average temperature had not increased for the previous five years, even though many climate scientists, and the media, were talking about an ever-warming planet powered by strong anthropogenic global warming. The initial debate was couched in cautious scientific terms but, because it ran counter to popular opinion, many dismissed it and questioned the motives of those pointing out these observational facts. But to the amazement of many, and the obvious annoyance of some, as the years passed all the major global temperature datasets showed no warming throughout the first decade of the 21st century and beyond. As this report shows, as the statistical significance of the standstill increased, the debate about its potential importance grew among many branches of science, even though many prominent scientists and institutions, and almost all of the media, were steadfastly looking the other way.

The problem for the alarmist position is that, as David Whitehouse points out, even some of the most prominent alarmists such as Hansen are now having to accept the reality of the stall, albeit they are using various dubious methods to deflect attention away from it. When crying that the world is heading for catastrophe, it is more than a little problematic when the world does not conform to the narrative. As such, it becomes ever more important to shift focus away from the harsh reality of the evidence that contradicts the narrative, and refocus attention on something that might support the narrative.

Perhaps I am wrong, but it is possible that Marcott et al have made ‘a pact with the devil’ (just a metaphor!). In return for creating the right narrative, they join a privileged elite of alarmist climate scientists, but do so at the cost of selling their scientific souls as the price. They have provided a paper which may be highly questionable, appears not to stand up to scrutiny, but have provided the material that is needed by both the media and IPCC to continue an alarmist narrative – in the face of evidence that is increasingly problematic for the alarmist case. In career terms, Marcott et al may have won from this. Their future work will undoubtedly be looked upon kindly by the gatekeepers of climate science.

However, only Marcott et al know their own motives, and I can only speculate on them here. On the one hand, there is a possibility (and one I would like to believe, even if I do not) that they think their paper is ‘sound’ but, in light of the problems in the paper, and the way it has been presented this would be hard to believe. On the other hand there is the possibility they made the trade-off. I can only wish that the former is true, because the latter is just depressing.

Note: The new batch of climategate emails are starting to cause a new stir. I am very pleased that the use of the emails has (so far) been cautious, and attention has been given to preventing non-climate science related emails being kept out of the public domain. We will undoubtedly find some interesting new insights as the tedious task of going through the emails progresses.

Marcott, S. A., J. D. Shakun, et al. (2013). “A Reconstruction of Regional and Global Temperature for the Past 11,300 Years.” Science 339(6124): 1198-1201

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The Leaked IPCC Report: The Sun’s Influence

[updates at end of post- I am not so sure that the issues are as I originally laid out – comments welcomed] I was a little cautious about one element of the critique of the leaked IPCC report. This was the strong claim made by Alec Rawls that the leaked IPCC report highlights the importance of the sun in driving climate change. There was a backlash to this. For example, the New Scientist said this:

Climate scientists are lining up to debunk this claim, and to explain that the bloggers have simply got it wrong. “They’re misunderstanding, either deliberately or otherwise, what that sentence is meant to say,” says solar expert Joanna Haigh of Imperial College London.

The sentence in question is the bold sentence in this passage:

Many empirical relationships have been reported between GCR or cosmogenic isotope archives and some aspects of the climate system (e.g., Bond et al., 2001; Dengel et al., 2009; Ram and Stolz, 1999). The forcing from changes in total solar irradiance alone does not seem to account for these observations, implying the existence of an amplifying mechanism such as the hypothesized GCR-cloud link. We focus here on observed relationships between GCR and aerosol and cloud properties.

Alec Rawls has provided a rebuttal of the critiques. It is long, and I believe quite complex, and can be found here. As such, I thought I would have a go at simplifying the point that he is making (in as simple language as possible), although do so at some risk I will get it wrong. I am not very familiar at all with this area of  science, but I think I have grasped the key principles of his argument:

  1. There is good empirical evidence that links the activity of the sun and global temperature
  2. One of these influences is total solar irradiance
  3. Total solar irradiance (which is known and can be accounted for) is, of itself, not sufficient to explain the linkage between the activity of the sun and the correlations with global temperature.
  4. Therefore something else must explain the linkages i.e. there is some other forcing mechanism from the activity of the sun that explains the linkage or ‘something’ is ‘amplifying’ the influence of the sun
  5. This might be the theoretical mechanism (backed by results from experimental work) in which solar activity impacts upon cloud formation

This is (in very simple terms) what I think is the gist of the paragraph quoted. There are points to note here.

  1. Observations are indicating a role for the activity of the sun on temperatures beyond what is currently being used in used in climate models. The models include solar irradiance, but not the other still uncertain/undiscovered amplifying mechanism.
  2. The passage accepts that the sun has a greater role in temperature than is currently used in climate models.

As you will have seen, there has been a response to Alec’s discussion which suggests that the context of the whole gives a different understanding. Indeed, there are even suggestions of ‘cherry picking’ and even outright dishonesty in the discussions of Alec’s argument. Central to the claim that the rest of the IPCC report is dismissive of the point in the paragraph is that other sections of the report cast doubt on the cloud formation theory.  Therefore, they claim that the rest of the report does not support a greater role for sun activity in the climate, and this is why there is nothing in the report which supports a greater role in climate change for the sun.

However, this is a very, very large problem, if that is their logic. For the moment we will accept their claim that the cloud theory is poorly supported (which is questionable). That merely means one explanation of the larger role of the sun in temperatures is poorly supported, and does nothing to argue against the evidence that the sun is a larger influence on temperature than is currently accepted in the climate models.

It just means that scientists should be looking harder for explanations of the larger role of the sun in the determination of climate [Update: RichardC reasonably points out that some scientists are already working hard on this, but the IPCC is uninterested]. In the interim they should still alter their models to include the larger role of the sun in driving climate [update: see John Hutlquist’s comment below for reasonable questions on this subject]. Whilst they might argue that they do not know what the additional amplifying mechanism is, they still need to accept the evidence that there is indeed an amplifying mechanism.

In summary, the argument in the IPCC report pretends that by casting doubts on a theory that exlains observation, they can then ignore the real implications of actual observations. These are not theory, and are observations. Casting doubts on a theoretical explanation of observations in no way makes the observations any less real! To pretend this is the case, is a sleight of hand, a magicians trick. It is getting you to look over there, whilst making the subject of interest disappear. If I have understood this correctly (and I am not certain of this), this is either a result of incompetence, or purposefully hiding an ‘inconvenient’ piece of evidence.

Important Note: In light of stepping out of my ‘comfort zone’ I welcome comments and corrections; for those who are reading; you should therefore check the comments below to see if any corrections have been made. Please note there may also be some comments which are from people who will seek to obscure rather than clarify the discussion that I have presented.

Update: In response to a comment below, I have added a large quote from the Economist, which discusses some of the science regarding the sun, climate and cloud formation. Being the Economist, it is well written, and for a lay audience. There is also a video with the original article which, if I remember when I first read the article, is very good.

Clouds are formed by the condensation of water vapour in the atmosphere around clusters of molecules such as ammonia and sulphuric acid. Ions created by the passage of cosmic rays can trigger the formation of such molecular seeds—a process of particular interest because the arrival of cosmic rays is regulated, in part, by the sun. The 11-year solar cycle, which governs the appearance of sunspots, also changes the sun’s magnetic field. That, in turn, affects the passage of cosmic rays (which are mostly protons released by distant supernova explosions), and thus the number of such rays that make it to Earth. Since clouds help regulate the climate, by reflecting sunlight back into space and cooling the atmosphere, some researchers think cosmic rays are a means by which changes in solar activity are translated into terrestrial climate change.

Just how much cosmic rays affect cloud formation has, however, remained elusive. A team at CERN, led by Jasper Kirkby, therefore decided to recreate both the solar cycle and the atmosphere in a lab. Their “cosmic rays” are generated by one of CERN’s particle accelerators. To simulate the atmosphere, they have built a special cloud chamber of their own, with the air manufactured from scratch, using liquid nitrogen and oxygen together with precise amounts of trace compounds, including sulphuric acid and ammonia.

A typical run at CLOUD, as the experiment is unimaginatively named, begins by tracking the growth of seeds from single molecules into clusters in the presence of ultraviolet radiation, which is known to encourage such growth. An electrical field removes any ions present, so the rate of seed growth should be equivalent to that in nature with no cosmic rays around. Next, the field is switched off, allowing actual cosmic rays to permeate the chamber for a while. Finally, a beam of artificial rays from the accelerator is added to the mix.

By comparing rates of seed formation during the different phases of the experiments, the researchers have been able to put a figure on cosmic rays’ contribution to the process. The results, reported in this week’s Nature, suggest naturally occurring rays enhance seed-formation rates by a factor of ten. That implies the rays’ varying intensity could indeed affect the climate.

Dr Kirkby and his colleagues remain cautious about the result, however, because of a second finding. To their surprise, they discovered that the seed-formation rates for sulphuric acid and ammonia are between a tenth and a thousandth of those needed to account for the cloud seeding actually seen in the atmosphere. That suggests other compounds are important, too—and this, in turn, implies that current climate models, which assume most seeds are made of ammonia or sulphuric acid, may require revision.

You may also wish to see this earlier article in the Economist, which gives further background, as it highlights the theory of Henrik Svensmark, who is a key theorist on the subject of cloud formation. I believe the science has moved ahead since these articles, but they do give a sense of the science at issue.

Another update in response to the comments and a little more consideration: This is with regards to the findings of correlations between the activity of the sun. There is a well worn statement that correlation does not equal causation (I recently stumbled across an interesting history of this, but forget where I found it, sorry). The best example I have seen as a simple illustration is that ice cream eating is highly correlated with hot weather, therefore eating ice cream causes hot weather (or the sun to shine). The point here is that correlations need a causal explanation. This is why the cloud seeding theory is important, as are other theories that link the activity of the sun to climate. However, as John Hutlquist points out in his comment, there are some correlations that are hard to ignore.

As you will note, I am starting to rethink a little on this issue. Science is about theory and observation, and that theory should be tested to see whether it is a true description of reality. There has to be theory in addition to observation. Added to this we have the question of intuitive plausibility. It seems intuitively plausible that the major driver of climate is the sun, but that does not make it true. However, when considering an intuitively plausible explanation and a less intuitively plausible explanation (i.e. the plausibility that human derived CO-2 emmissions are more influential in climate change than the sun), then it seems that there should be a desire to examine the more plausible explanation in great depth before settling on the less plausible.

In other words, we have some interesting observational evidence that is suggestive that the sun is more influential as a driver of climate than manmade CO_2. However, the mechanism for how the sun might have greater influence than the know solar irradiance is still a subject of hypothesis and theory testing. It appears, however, that certain members of the scientific community are resistant to the possibility of the sun as a more significant driver of climate than CO_2, and wish to stick with their own (less intuitively plausible) explanation in the face of a more plausible explanation. They do not seem to want to engage with those who are engaging in the process of testing of an alternative hypothesis. Further, whilst their current hypothesis has resulted in model predictions, the predictions are not doing well in face of observation. This should be a driver towards greater interest in the alternative (and more intuitively plausible) hypothesis.

As I have pointed out earlier in the post, I am not in a position to evaluate the science, but I think I am starting to see something of the questions raised in the IPCC leaked report. If they can demonstrate that the current theories of amplification of the influence of the sun are wrong (which I gather they have not), then they could argue that there is no mechanism given for how the sun might be a more important driver for climate than CO_2, and then argue that without a mechanism, the observations are nothing more than coincidence. Correlation and causation are not enough. However, their own theory, as expressed in models, is failing to predict, meaning that their theory is problematic, and that the observations of solar drivers of climate seem to better fit observations of the climate.

In these circumstances, rather than seeking to discredit the sun as a more significant driver of climate, they should be actively looking themselves at the possibilities, and seeking their own explanations. Instead, their minds seem made up so that, whatever faults there are in their own theory, it must be defended to the hilt. After all, the big ball of energy that is the sun seems a plausible candidate for being a major driver of the climate. This stiff-necked approach now seems to me to be the issue at hand. Why are the IPCC scientists so resistant to the alternative explanation for climate variability in the face of the problems with their own theory? There are observations, there are possible causal mechanisms, there are interesting questions which should spur scientific interest (all science commences with questions). Why the disinterest?

Note: A second thanks to John for his comment on models, which spurred this rethink. I think he was gently making the correlation/causation point in the question about models.

The IPCC AR5 Leak: why do the IPCC object?

There has been considerable excitement over the AR5 leak (for those not so involved in the climate change debate, this the latest major report from the IPCC). The leak was made by Alex Rawls, an expert reviewer on the IPCC, and he says:

I believe that the leaking of this draft is entirely legal, that the taxpayer funded report report is properly in the public domain under the Freedom of Information Act, and that making it available to the public is in any case protected by established legal and ethical standards […]

With regards to whether the leaking is a good or bad thing, in an ethical sense, Donna Laframboise covers the question extremely well, by quoting Rajendra Pachauri, the head of the IPCC, on his views and statements about transparency. This is just one of several quotes provided by Donna:

“So you can’t think of a more transparent process…than what we have in the IPCC. I would only put that forward as valid reasons to accept the science and the scientific assessments that are carried out.” – newspaper interview, June 2007

In light of the many quotes that emphasise transparency, the publication of an interim draft should not raise any problems, as it shows an element of the process in developing the final report. This seems to be the meaning of transparency; showing the stages and processes for how conclusions were developed in the IPCC reports. However, the IPCC is unhappy about the leak, and the Guardian reports:

The IPCC, which confirmed the draft is genuine, said in a statement: “The IPCC regrets this unauthorized posting which interferes with the process of assessment and review. We will continue not to comment on the contents of draft reports, as they are works in progress.”

As such, it seems that the idea of transparency is more rhetoric than reality. Indeed, one would have thought that, if the IPCC really did value transparency, they would be celebrating the interest that the leak has generated; there is considerable interest in their process. Furthermore, it is not entirely clear how leaking the report might interfere in the review process. Is it that the leaked report will make reviewers alter the nature of their reviews? Surely a review should be an objective assessment of the nature of the science being presented, and should therefore be ‘immune’ from any commentary that might be made on the basis of the leak.

There are some concerns regarding the leak. The first is that Alex Rawls also discussed that the leaked report includes admission of enhanced solar forcing. This part of the story has been taken up by several people, such as James Delingpole in the Telegraph. I will leave the analysis of the science to others, but the gist of the story is that sections of the report admit that solar forcing has a greater impact on the climate than previously accepted. However, there are indications that the conclusions being drawn do not reflect the actual substance of the report overall. For example, at the Reference Frame blog, the conclusion is that the only real change is that there are now references to the work of Svensmark et al., which offers a consideration of mechanisms for solar forcing. The post concludes:

The situation, as I see it, is that the IPCC writing process is still controlled purely by the staunch, stubborn alarmists. They may have just split into several camps that differ in the opinion whether it should be legal to pronounce the name of Henrik Svensmark, albeit with a negative sentence required immediately afterwords, or whether his name should remain a blasphemy.

The question of what the report really proposes will no doubt be clarified over time as the science focused blogs start to digest the detail of the report. In the meantime, I would urge caution, and not jumping to hasty pronouncements over the content of the report. Indeed, Anthony Watts is pointing at a ‘bombshell’ to be found in the following Figure 1.4 from the AR5 draft, and will follow up with an essay in the near future:

IPCC_Fig1-4_models_obs

For the moment, I will leave the figure undiscussed, but it will be interesting to see Anthony’s essay, once he has had the time to examine the details and context surrounding the figure. The reason why I give this example is that, if it is indeed a ‘bombshell’, it may indicate why the IPCC would not seek the transparency that it claims; the early drafts of the reports may include material that can serve to raise doubts about the science that is finally used in the final report.  In the end, the final report is selective in the material that is presented, and how the material is presented. This means that some material will be excluded, and also that the emphasis in the final report will also be determined by the review process.

Real transparency would see this process of selection, rejection, and choice of emphasis take place in the public domain. For example, the ‘bombshell’ figure above might have finally been excluded from the report (we have no way of knowing what would have happened without the leak, of course), and transparency would demand that there is an explanation for its exclusion, if it is indeed a bombshell (which I suspect it is). After all, this would be part of the overall science, and any treatment of the science is a matter of the public interest.

In particular, as Alec Rawls points out, the IPCC reports are used as a basis for policy decisions, and those policy decisions can have far reaching impacts. The real question surrounding the leak, therefore, is why the IPCC might object, and why it does not conduct the entire report drafting process in the clear light of day? There should, in other words, be no need for leaks, as a genuinely transparent process would make leaks irrelevant.

Update: I see that the Climate Conversation Group has picked up on the leak, but nothing so far in the New Zealand press (for the media I checked).

Update 2: The full IPCC statement on the leak can be found here. I think it simply reinforces the points I am making here.

Climate Change and Disasters

The latest output of the IPCC has caused some stir, which is ‘The IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation‘. This is some commentary from Richard Black of the BBC who was leaked the report:

While it is “likely” that anthropogenic influences are behind the changes in cold days and warm days, there is only “medium confidence” that they are behind changes in extreme rainfall events, and “low confidence” in attributing any changes in tropical cyclone activity to greenhouse gas emissions or anything else humanity has done.

[and]

And for the future, the draft gives even less succour to those seeking here a new mandate for urgent action on greenhouse gas emissions, declaring: “Uncertainty in the sign of projected changes in climate extremes over the coming two to three decades is relatively large because climate change signals are expected to be relatively small compared to natural climate variability”.

[and]

It’s impossible to read the draft without coming away with the impression that with or without anthropogenic climate change, extreme weather impacts are going to be felt more and more, simply because there are more and more people on planet Earth – particularly in the swelling “megacities” of the developing world that overwhelmingly lie on the coast or on big rivers close to the coast.

This is from Andrew Revkin of the New York Times:

While the summary warns of enormously increasing risks from drought and flooding in decades to come, it is bound to disappoint climate campaigners — and it frustrated at least one, Joe Romm, even before it was released. The section on disaster losses correctly reflects the uncertainty injected in such analysis by confounding factors, including rapidly shifting human populations and the paucity of solid data over long periods.

Perhaps the most amusing take on the report comes from Joe Romm, who is mentioned in the New York Times report, who headlines that the report was a missed opportunity to warn of coming catastrophe. However, he takes some comfort in the following:

Fortunately, the public already understands that global warming makes extreme weather more severe, as new polling reveals:

[diagram of poll removed]

September polling by ecoAmerica found that 57% of Americans already understand “If we don’t do something about climate change now, we can end up having our farmland turned to desert.”

That’s okay then. Even if the sainted IPCC says things that do not agree with doom-mongering, as long as people are scared, all is well with the world. He then goes on to cite a series of articles that he believes prove that global warming is a catastrophe. Sitting in the middle of the debate, Judith Currie has the following to say about the report:

This report is better than I expected, although I suspect that some of their conclusions are based on weak arguments  (we will have to wait for the full report).  The two most important aspects IMO are the recognition of the importance of natural variability and also vulnerability.  The dominance of natural variability for the past 40-60 years  in determining extreme events makes the AGW extreme events attribution exercises (see here) seem even more pointless.  The weakest part of the report is the high confidence level of the future projections (including  one “virtually certain.”)  I suspect that different authors worked  on the “Observations” section than those working on the “Future” chapter; too bad the “Future” authors didn’t read the “Observations” section first.

I would most strongly recommend that, if following any of the links here, the most interesting is Judith’s evaluation of the report, which is detailed and incisive. On the skeptic side, this is what the Global Warming Policy Foundation has to say about the report:

If and when mankind’s influence becomes apparent it may be just as likely to reduce the number of extreme weather events as increase them.

Surveying the state of scientific knowledge IPCC scientists say they cannot determine if mankind’s influence will result in more, or fewer, extreme weather events over the next thirty years or more.

Jo Nova has the a more direct and scathing approach to the report:

This is another big tipping point on the slide out of the Great Global Scam. IPCC scientists — facing the travesty of predictions-gone-wrong — are trying to salvage some face, and plant some escape-clause seeds for later. But people are not stupid.

A conveniently leaked IPCC draft is testing the ground. What excuses can they get away with? Hidden underneath some pat lines about how anthropogenic global warming is “likely” to influence… ah cold days and warm days, is the get-out-of-jail clause that’s really a bombshell:
“Uncertainty in the sign of projected changes in climate extremes over the coming two to three decades is relatively large because climate change signals are expected to be relatively small compared to natural climate variability”.

Translated: The natural climate forces are stronger than we thought, and we give up, we can’t say whether it will get warmer or colder in the next twenty years.

This multipurpose prediction means that in the future, if it’s colder, they’re right; if it’s warmer, they’re right; and they have it covered for more or less storms, floods, droughts, blizzards and frost too.

Jo captures some of the shifting sands of the debate. Despite all the uncertainties, one way or another, we are all nevertheless doomed. It is part of the ongoing trend in the AGW camp to muddy the waters as predicted outcomes of climate change are not taking place/following the script. interestingly in the updates, Jo quotes ‘scientists’ who nevertheless insist that the signal of AGW will emerge one day, with the implication that the report changes nothing about the necessity for urgent action. Jo points out:

Wait for it, in trying to control the damage from this, Prof Palutikof reveals a deeply unscientific, religious mindset. There is no signal yet of man made influence, but she “knows” it will emerge. A real scientist would wait for the observation. [below was in quotes in the original]

Jean Palutikof, director of the National Climate Change Adaptation Research Facility at Griffith University, in Queensland, said the findings of the UN report would “not surprise anyone involved in climate science”. Professor Palutikof said it would take a while for the effects of climate change to become visible. But without action, she said, “gradually, over time, that signal will emerge with resounding clarity”.

From my perspective, I view the report with the same cynical view that I apply to all the output of the IPCC. As I have discussed before, there are some good and honest scientists working for the IPCC, but the organisation also has some characteristics that mean that their reports are not to be trusted. In other words, it is not possible to dismiss the IPCC reports which are supportive of the AGW thesis, then accept the reports that are less supportive as being ‘good science’.

However, the report is interesting in that it seems that there is finally some explicit and very clear acknowledgement of the uncertainties involved in understanding the impacts of climate, although the coverage is patchy (again, see Judith Currie’s discussion). This seems to be a positive step forward, but we will have to wait for the full report in February to see whether the devil is in the detail.