The Nobel Prize (for propaganda)

These and other models are only as smart as the scientists who build them -- they rely on data that scientists have gathered about the real world, and the accuracy of estimates about how all the factors fit together (Is an experienced coach more or less important than young defensive backs?).

They also depend on the computers running them. To accurately depict how individual clouds form and disappear, for instance, the computers that model climate change would need to be a million times faster. For now, the effects of clouds have to be estimated.

But scientists say complexity doesn't guarantee accuracy. The best test of a model is to check it against reality.

"We're never going to perfectly model reality. We would need a system as complicated as the world around us," said Ken Fleischmann, a professor of information studies at the University of Maryland. He said scientists needed to make the uncertainties inherent in models clear: "You let people know: It's a model. It's not reality. We haven't invented a crystal ball."

*****​

"It's an educated, scientifically based guess," said Michael Winton, an oceanographer at the National Oceanic and Atmospheric Administration. "But it's a guess nonetheless."

But Warren Meyer, a mechanical and aerospace engineer by training who blogs at www.climate-skeptic.com, said that climate models are highly flawed. He said the scientists who build them don't know enough about solar cycles, ocean temperatures and other things that can nudge the earth's temperature up or down. He said that because models produce results that sound impressively exact, they can give off an air of infallibility.

But, Meyer said -- if the model isn't built correctly -- its results can be both precise-sounding and wrong.

"The hubris that can be associated with a model is amazing, because suddenly you take this sketchy understanding of a process, and you embody it in a model," and it appears more trustworthy, Meyer said. "It's almost like money laundering."

*****​

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The past year has been a busy one for statisticians interested in climate change. In February this year, the Intergovernmental Panel on Climate Change (IPCC) issued the Summary for Policymakers of its Fourth Assessment Report, which included IPCC's strongest statement yet about human influence being “very likely” a direct cause of observed global warming. The U.S. government's Climate Change Science Program (CCSP) is in the midst of producing 21 “special assessment reports” on different aspects of climate change as it applies to North America. And in 2006, several statisticians were involved in a well-publicized controversy over the so-called “hockey-stick curve”. This controversy was the central feature of a late-breaking session entitled “What is the Role of Statistics in Public Policy Debates about Climate Change?” that was organized jointly by Edward Wegman (George Mason University) and myself at the 2006 Joint Statistical Meetings. The session took place in front of a standing-room-only audience and was chaired by Doug Nychka (National Center for Atmospheric Research).

The three speakers were Ed Wegman, J. Michael Wallace of the Department of Atmospheric Sciences, University of Washington, and myself. Ed and Mike both talked about the hockey stick reconstruction. Ed focused on statistical flaws that, in his view, render much of the current literature on this subject of doubtful validity.

*****​

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There has been the most extraordinary series of postings at Climate Audit over the last week. As is usual at CA, there is a heavy mathematics burden for the casual reader, which, with a bit of research I think I can now just about follow. The story is a remarkable indictment of the corruption and cyncism that is rife among climate scientists, and I'm going to try to tell it in layman's language so that the average blog reader can understand it. As far as I know it's the first time the whole story has been set out in a single posting. It's a long tale - and the longest posting I think I've ever written and piecing it together from the individual CA postings has been a long, hard but fascinating struggle. You may want to get a long drink before starting, and those who suffer from heart disorders may wish to take their beta blockers first.


At some time or another, most people will have seen the hockey stick - the iconic graph which purports to show that after centuries of stable temperatures, the second half of the twentieth century saw a sudden and unprecedented warming of the globe. This was caused, we were told, by mankind burning fossil fuels and releasing carbon dioxide into the atmosphere. For a while, the hockey stick was everywhere - unimpeachable evidence that mankind was damaging the planet - an impact that would require drastic measures to reverse. The stick's most famous outing however was just a couple of years ago when it made a headlining appearance in Al Gore's drama-documentary, An Inconvenient Truth. The revelation of the long, thin graph with its dramatic temperature rise in the last few decades, and the audience gasps that accompanied it, is something of a key moment for many environmentalists.

Shortly after its publication, the hockey stick and its main author, Michael Mann, came under attack from Steve McIntyre, a retired statistician from Canada. In a series of scientific papers and later on his blog, Climate Audit, McIntyre took issue with the novel statistical procedures used by the hockey stick's authors. He was able to demonstrate that the way they had extracted the temperature signal from the tree ring records was biased so as to choose hockey-stick shaped graphs in preference to other shapes, and criticised Mann for not publishing the cross validation R2, a statistical measure of how well the temperature reconstruction correlated with actual temperature records. He also showed that the appearance of the graph was due solely to the use of an estimate of historic temperatures based on tree rings from bristlecone pines, a species that was known to be problematic for this kind of reconstruction.


The controversy raged for several years, involving blue riband panels, innumerable blog postings, endless name-calling and dark insinuations about motivations and conflicts of interest. In May 2005, at the height of the controversy, and on the very day that McIntyre was making a rare public appearance in Washington to discuss his findings, two Mann associates, Caspar Amman and Eugene Wahl, issued a press release in which they claimed that they had submitted two manuscripts for publication, which together showed that they had replicated the hockey stick exactly, confirmed its statistical underpinnings and demonstrated that McIntyre's criticisms were baseless. This was trumpeted as independent confirmation of the hockey stick. A few eyebrows were raised at the dubious practice of using a press release to announce scientific findings. Some also noted that on the rare occasions that this kind of announcement is made, it tends to be about papers that have been published, or at least accepted for publication. To make such a dramatic announcement about the submission of a paper was unusual in the extreme.

The first of these papers ("the GRL paper") was submitted to Geophysical Research Letters, the journal of the American Geophysical Union. It took the form of a rebuttal of a McIntyre paper that had attacked the hockey stick and had been published in the same journal. From the first, the McIntyre paper had been controversial. Apart from Amman and Wahl's paper, there were three other papers taking issue with it. However, it turned out that some of these attempted rebuttals were less well formed than others. In fairly short order, Amman and Wahl's paper was rejected, many of its criticisms either relating to other McIntyre papers than the one at hand, or relying on the second paper for their arguments. Since the second paper was unpublished, it was effectively impossible for McIntyre to defend himself against these criticisms. Shortly after Amman and Wahl's paper was rejected, another of the rebuttals, that of a physicist called David Ritson, was also shot down by the journal's editors.


Meanwhile the second, longer paper ("the CC paper") had started its long road to publication at the journal Climatic Change. This article purported to be a replication of the hockey stick and confirmation of its scientific correctness. However, in a surprising turn of events, the journal's editor, prominent global warming catastrophist Steven Schneider, mischievously asked none other than Steve McIntyre to be one of the paper's anonymous peer reviewers.

We have seen above that one of the chief criticisms of the hockey stick was the fact that its author, Michael Mann, had withheld the validation statistics so that it was impossible for anyone to gauge the reliability of the reconstruction. These validation statistics were to be key to the subsequent story. At the time of their press release Wahl and Amman had made public the computer code that they'd used in their papers. By the time their paper was submitted to Climatic Change, McIntyre had reconciled their work with his own so that he understood every difference. And he therefore now knew that Wahl and Amman's work suffered from exactly the same problem as the hockey stick itself: the R2 number was so low as to suggest that the hockey stick had no meaning at all, although another statistic, the reduction of error statistic (or RE) was relatively high. It was only this latter figure that had been mentioned in the paper. In other words, far from confirming the scientific integrity of the hockey stick, Wahl and Amman's work confirmed McIntyre's criticisms of it! McIntyre's first action as a peer reviewer was therefore to request from Wahl and Amman the verification statistics for their replication of the stick. Confirmation that the R2 was close to zero would strike a serious blow at Wahl and Amman's work.



Wahl and Amman's response was to refuse any access to the verification numbers, a clear flouting of the journal's rules. As a justification of this extraordinary action, they claimed that they had shown that McIntyre's criticisms had been rebutted in their forthcoming GRL paper, despite the fact that the paper had been rejected by the journal some days earlier. At the start of July, with his review of the CC paper complete, McIntyre took the opportunity to probe this point, by asking the journal to find out the anticipated publication date of the GRL paper. Wahl and Amman were forced to admit the rejection, but they declared that it was unjustified and that they would seek publication elsewhere.


With the replication of the hockey stick in tatters, reasonable people might have expected some sort of pause in the political momentum. Seasoned observers of the climate scene, however, will be unsurprised to hear that global warming eminences grises like Sir John Houghton and Michael Mann continued to cite the Wahl and Amman papers despite the CC paper being in publishing limbo and the GRL paper being apparently dead and buried. The Wahl and Amman press release was not withdrawn either.


Events soon took another surprising turn., It was announced that the editor in chief of Geophysical Research Letters, Jay Famiglietti, had taken over the file for the McIntyre paper and its responses. This was justified he claimed, because of the high number of responses - four - that the McIntyre paper had received. That two of those responses had been rejected and were no longer in play was not mentioned. The reason for the change quickly became apparent though when, at the end of September, the rejected response from David Ritson turned out not only to have been re-submitted but had also been accepted for publication. This was another clear breach of the journal's rules, which required that an article's author should be able to comment on responses before they were accepted. Famiglietti however refused to make any on-the-record comments about why he behaved as he did.


If McIntyre had any suspicions about the implications of Famiglietti's malfeasance, he must have been quite certain when, shortly afterwards, hockey stick author Michael Mann commented on his RealClimate blog that both the CC and the GRL papers were going to be accepted shortly. Sure enough, in the last week of September, the GRL paper was resubmitted and revisions were made to the CC paper. Both papers were back in play again.


As 2005 neared its end, two important events loomed large. The first was the year end deadline for submission of papers for the IPCC's Fourth Assessment Report on the state of the climate, and realisation soon dawned on McIntyre and the observers of the goings-on at GRL:

the IPCC needed to have the Wahl and Amman papers in the report so that they could continue to use the hockey stick, with its frightening and unprecedented uptick in temperatures. Mountains were going to be moved to keep the papers in play.


The other important happening was the fall meeting of the American Geophysical Union, which would be attended by many of the big names in paleoclimate and at which both McIntyre and Amman would be making presentations. McIntyre's plan was to use the question and answer session after Amman's presentation to once again press for the R2 number for the hockey stick, a figure that had never been released, despite it being constantly requested over the previous years by McIntyre, journals, politicians and journalists. Sure enough, when confronted, Amman once again prevaricated.


After the session, McIntyre attempted to clear the air by inviting Amman to lunch. In the circumstances, this seems to have been a relatively amicable affair, but McIntyre's suggestion that he and Amman write a joint paper outlining where they agreed and where they differed was not taken up. When McIntyre later formalised this offer in an email, Amman failed even to acknowledge it.


While the AGU was meeting in San Francisco, Climate Change had provisionally accepted Wahl and Amman's CC paper, any objections which might have been raised by McIntyre swept aside by simple means of not inviting him to review the second draft. The resubmitted version of the paper turned out to be almost identical to the old one, except that a new section on the statistical treaments had been added, presumably as a condition of acceptance. And here there was an upside because, buried deep within the paper, Amman and Wahl had quietly revealed their verification R2 figures, which were, just as McIntyre had predicted, close to zero for most of the reconstruction, strongly suggesting that the hockey stick had little predictive power. Their decision to reveal these key data is necessarily obscure, but may well have been prompted by McIntyre's decision to file a complaint of academic misconduct about Amman with his employers, UCAR. Although the complaint was rejected, it may well have put sufficient pressure on Amman and the journal to show the numbers that everyone wanted to see.


The CC paper's provision acceptance date was December 12th, just a few days before the AR4 deadline. Strangely the version that was accepted seems to have been dated 24th Feb 2006, so according to its rules the IPCC shouldn't have been able to considered it. And what is more, it appears that the new sections discussing the statistical verifications were only added in this post year-end version. As McIntyre put it:

So under its own rules, is IPCC allowed to refer to Ammann and Wahl [2006]? Of course not. Will they? We all know the answer to that. When they refer to Ammann and Wahl [2006], will they also refer to its confirmation of our claims about MBH verification r2 statistics. Of course not. That information was not available to them in December. But wait a minute, if Ammann and Wahl was in press in December, wouldn’t that information have been available to them? Silly me.​

In other words, the version of the paper which had gone forward to the IPCC didn't include the adverse verification statistics, but the version accepted by the journal did. The IPCC got their rebuttal of McIntyre and the journal got a fig leaf of respectability to cover up its duplicity.


By March, the CC paper had been fully accepted, but there was to be another hiccup that would threaten its existence. After all the shenanigans at GRL with the replacement of the editor and the resubmission of letters, the journal decided once again to reject Wahl and Amman's attempt to rebut McIntyre's work. Ostensibly this was because the arguments were "already out there", but the truth was surely that there were so many holes in the statistical arguments as to make their publishing an embarrassment to the journal.


This new rejection was a problem for the CC paper, as I will explain below. When using an R2 verification, researchers can refer to tables of benchmarks to gauge the significance of their results. Now that the fact that the hockey stick and Amman and Wahl's replication of it were public, Amman was arguing that the correct measure of significance was in fact the alternative RE statistic. His problem was that for RE statistics, there are no tables of benchmarks for the researcher to refer to - he has to establish a benchmark of his own by other means. And Amman had done this in the GRL paper which had just been rejected. Without the GRL paper, he couldn't even argue that his results in CC were statistically significant.

There is a rule of thumb for RE statistics: this says that positive RE numbers have some significance while negative ones do not. Unfortunately for Amman, this rule applies only to linear regressions; as the hockey stick was clearly not linear, it couldn't apply. The original hockey stick authors had claimed that they had created a benchmark through other means, and that the figure was still zero. Now, while they had been silent on the issue in their original GRL submission, Amman and Wahl announced in their resubmission that they had performed benchmarking calculations and that had confirmed that the significance level for the RE should remain at zero.


However, now that the resubmission had been rejected by GRL, the "establishment" of this benchmark was cancelled out, and the statistical arguments in the CC paper which relied on it could no longer be maintained.


And then silence. A year later, the CC paper was nowhere to be seen, despite having been accepted for publication. It was stuck in a kind of publishing limbo once again. This left the IPCC and Climatic Change with a problem. McIntyre observed:

I’m intrigued as to what the final Wahl and Ammann version will look like. They have an intriguing choice: the inclusion of a reference to this article in AR4 was premised on their article being “in press” which would prohibit them from re-working their article to deal with the GRL rejection. But the article needs to be re-worked since it will look pretty silly to describe their GRL article as “under review” over 18 months after it has been rejected.​

In the background, however, much had been happening. Suddenly in September 2007, and with the IPCC report published, the CC paper suddenly appeared, preceded in the same journal by another paper by the same authors. What had happened was that Wahl and Amman were quietly allowed to rewrite their rejected GRL paper and submit it to Climatic Change instead. All reference to the rejected GRL paper in the CC paper could be replaced by reference to the new paper, (which I will call the Jesus paper, in light of its extraordinary resurrection and for lack of any less confusing name). With identical authorship, and a maze of cross-references between them, the two CC papers were carefully designed to make understanding how their arguments relied on each other as difficult as possible.


The beauty of this approach was that it allowed for retention of the original acceptance date for the CC paper, and hence its inclusion in the IPCC process. It did leave them with the embarrassing problem that a paper that was allegedly accepted in March 2006 relied upon another paper that even the journal itself said was only received until August (and in reality, is was even later than that) Readers should note that this matters because unless the paper was accepted by the journal by the deadline, it should not have been accepted by IPCC for inclusion in the Fourth Assessment Report. But the IPCC needed the CC paper and despite the inconsistency being pointed out to them, the IPCC they waved the objections aside as irrelevant.

The CC paper argument leads from the text, to the appendix and then onto the Jesus paper. At places in the Jesus paper the argument referred back to the CC paper creating a neat, if logically flawed, circular argument. One notable feature of the CC paper and the Jesus paper was that they relegated some of their key argumentation to their Supplementary Information (SI) sections, online appendices to the published papers. In particular, the Jesus paper stated that the statistical discussions and more precisely, the establishment of RE benchmarks could be seen there. To have key arguments in the SI was most unusual and it quickly became apparent why it had been done: the SI was nowhere to be seen. Even the peer reviewers appear not to have had access, and once again, Amman refused McIntyre's request for the data and code. His reply to this request was startling (and remember that Amman is a public servant):

Under such circumstances, why would I even bother answering your questions, isn’t that just lost time?​

Again, everything fell silent. For the next year nothing more was heard of the two papers. McIntyre pressed from his blog for release of the SI and the politicians were able to quietly take advantage of the political space created by the IPCC report. Then, just a few weeks ago, and entirely unannounced, Wahl and Amman's Supplementary Information suddenly appeared on Caspar Amman's website, some three years after that first press release announcing the refutation of McIntyre's work. With it, and a godsend to McIntyre, was the code used to establish the benchmark for the RE statistic. With no more than a few days work, McIntyre was able to establish exactly what had been done.


You will remember that Amman and Wahl had claimed that they had established a benchmark of zero for a 99% significant RE score - that is to say, there is only a 1% chance that you might have got that score by chance. McIntyre had, much earlier, shown that if you ran red noise through the process, you could get RE scores of more than 0.5. (Red noise is best described as a "random walk" - a line which wiggles at random, but is not entirely random like white noise.) To reduce your chance of random error to 1% you actually needed to score 0.54 for RE. How Amman had come up with zero as his benchmark was a mystery.


Now, with the code in front of him, McIntyre could see exactly what Wahl and Amman had done. And what they had done was to calculate almost exactly the same figure as he had! The number they had arrived at was 0.52, just a whisker away from McIntyre's own 0.54, but they had reported to the world that it was sufficient only to score a positive number! Of course, this wasn't picked up by the peer reviewers because, as we've seen, they didn't have access to the Supplementary Information, but the IPCC's purposes had been served - the hockey stick found its way intact into the Fourth Assessment Report, unscathed by skirmishes with inconvenient statistical truths.


However, the figure of 0.52 was insufficient for W&A's purposes. Their problem was that the key component of the hockey stick had a verification RE of 0.48, leaving it tantalisingly just below the calculated benchmark. They needed it to be in the top rank and getting it there was going to be tricky. For each simulation, a thousand runs through the statistical sausage machine were perfomed and the RE number, the correlation with the temperature record, was recorded. Then all the runs were sorted in order of RE value, the best runs having the highest RE and the worst the lowest. W&A needed to show that the hockey stick RE was right up there with the best simulations - in the top one percent. While its RE was high, it wasn't good enough. And it was no good simply removing runs which had a higher score than the hockey stick, since this would not increase its position enough - they would have been reducing the total number of runs as well as the number of runs which were scoring better than the hockey stick. To get the answer they needed, the higher scoring runs had to be made to be lower than the hockey stick, but left in the calculation.

To do this, Wahl and Amman came up with a value which they called a calibration/verification RE ratio. As the name suggests, this was the ratio of the two RE numbers for calibration and verification. This ratio is however, entirely unknown to statistics, or to any other branch of science. But it was not plucked out of the air. The ratio and the threshold value which was set for it by Wahl and Amman was carefully calculated. They argued that any run with a ratio less than 0.75 should be assigned a score of -9999. Since the hockey stick had a score of 0.813, 0.75 was pretty much the highest level you could go to without rejecting the hockey stick itself. However if you set your ratio threshold too low, not enough runs would be rejected and the hockey stick would no longer be "99% significant". Some of the results of this ratio were entirely perverse - it was possible for a run that had scored a reasonably good RE in the calibration (there was a good correlation between it and the actual temperatures) to be thrown out of the final assessment on the grounds that it had done very well in the verification - the correlation with actual temperatures was considered too good!


With this new, and pretty much entirely arbitrary hurdle in place, Wahl and Amman were able to reject several of the runs which stood between the hockey stick and what they saw as its rightful place as the gold standard for climate reconstructions. That the statistical foundations on which they had built this paleoclimate castle were a swamp of misrepresentation, deceit and malfeasance was, to Wahl and Amman, an irrelevance. For political and public consumption, the hockey stick still lived, ready to guide political decision-making for years to come.

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I read Willis Eschenbach’s post last week on Trust and Mistrust where he posed several questions and challenged scientists to respond to the same questions. So, below is my take on these questions. There are a couple points I need to make up front. First, I’m speaking for myself only, not as a representative of the National Snow and Ice Data Center or the University of Colorado. Second, I primarily study sea ice; climate science is a big field and I’m hardly a specialist in the technical details of many climate processes. However, I will provide, as best I can, the current thinking of most scientists working in the various aspects of climate science. Except where explicitly called for, I try to provide only scientific evidence and not my beliefs or personal opinions.

Also, I use the term “climate forcing” throughout. I’m sure this is familiar to most readers, but for clarity: a climate forcing is essentially anything that changes the earth’s global radiation budget (the net amount of radiative energy coming into the earth) and thus “forces” the earth’s climate to change.

Preface Question 1: Do you consider yourself an environmentalist?

Yes. However, I’m no tree-hugger. I don’t believe the environment should be preserved at all costs. I love my creature comforts and I don’t think we can or should ask people to significantly “sacrifice” for the environment. My feeling is that the environment has value and this value needs to be considered in economic and political decisions. In other words, the cost of cutting down a tree in a forest isn’t just the labor and equipment but also the intrinsic value of the tree to provide, among other things: (1) shade/scenery/inspiration for someone talking a walk in the woods, (2) a habitat for creatures living in the forest, (3) a sink for CO2, etc. And I don’t doubt at all that Willis is an environmentalist. However, whether one is an environmentalist or not doesn’t make the scientific evidence more or less valid.

Preface Question 2: What single word would you choose to describe your position on climate science?

Skeptic. This may surprise many people. But any good scientist is a skeptic. We always need to challenge accepted wisdom, we need to continually ask “does this make sense?, does it hold up?, is there another explanation?, is there a better explanation?” – not just of the work of other scientists, but also of our own work. However, a good skeptic also recognizes when there is enough evidence to place confidence in a finding. Almost all new theories have initially been looked upon skeptically by scientists of the time before being accepted – gravity, evolution, plate tectonics, relativity, quantum mechanics, etc.

Question 1. Does the earth have a preferred temperature, which is actively maintained by the climate system?

Willis says that he “believes the answer is yes”. In science “belief” doesn’t have much standing beyond initial hypotheses. Scientists need to look for evidence to support or refute any such initial beliefs. So, does the earth have a preferred temperature? Well, there are certainly some self-regulating mechanisms that can keep temperatures reasonably stable at least over a certain range of climate forcings. However, this question doesn’t seem particularly relevant to the issue of climate change and anthropogenic global warming. The relevant question is: can the earth’s temperature change over a range that could significantly impact modern human society? The evidence shows that the answer to this is yes. Over the course of its history the earth has experienced climatic regimes from the “snowball earth” to a climate where ferns grew near the North Pole. Both of those situations occurred tens or hundreds of millions of years ago; but more recently, the earth has experienced several ice age cycles, and just ~12,000 years ago, the Younger Dryas event led to significant cooling at least in parts of the Northern Hemisphere. So while the earth’s climate may prefer to remain at a certain stable state, it is clear that the earth has responded significantly to changes in climate forcings in the past.

Question 2: Regarding human effects on climate, what is the null hypothesis?

I will agree with Willis here – at one level, the null hypothesis is that any climate changes are natural and without human influence. This isn’t controversial in the climate science community; I think every scientist would agree with this. However, this null hypothesis is fairly narrow in scope. I think there is actually a more fundamental null hypothesis, which I’ll call null hypothesis 2 (NH2): are the factors that controlled earth’s climate in the past the same factors that control it today and will continue to do so into the future? In other words are the processes that have affected climate (i.e., the forcings – the sun, volcanic eruptions, greenhouse gases, etc.) in the past affecting climate today and will they continue to do so in the future? A basic premise of any science with an historical aspect (e.g., geology, evolution, etc.) is that the past is the key to the future.

Question 3: What observations tend to support or reject the null hypothesis?

Let me first address NH2. We have evidence that in the past the sun affected climate. And as expected we see the current climate respond to changes in solar energy. In the past we have evidence that volcanoes affected climate. And as expected we see the climate respond to volcanic eruptions (e.g., Mt. Pinatubo). And in the past we’ve seen climate change with greenhouse gases (GHGs). And as expected we are seeing indications that the climate is being affected by changing concentrations of GHGs, primarily CO2. In fact of the major climate drivers, the one changing most substantially over recent years is the greenhouse gas concentration. So what are the indications that climate is changing in response to forcing today as it has in the past? Here are a few:

1. Increasing concentrations of CO2 and other GHGs in the atmosphere

2. Rising temperatures at and near the surface

3. Cooling temperatures in the stratosphere (An expected effect of CO2-warming, but not other forcings)

4. Rising sea levels

5. Loss of Arctic sea ice, particularly multiyear ice

6. Loss of mass from the Greenland and Antarctic ice sheets

7. Recession of most mountain glaciers around the globe

8. Poleward expansion of plant and animal species

9. Ocean acidification (a result of some of the added CO2 being absorbed by the ocean)

It is possible that latter 8 points are completely unrelated to point 1, but I think one would be hard-pressed to say that the above argues against NH2.

Of course none of the above says anything about human influence, so let’s now move on to Willis’ null hypothesis, call it null hypothesis 1 (NH1). Willis notes that modern temperatures are within historical bounds before any possible human influence and therefore claims there is no “fingerprint” of human effects on climate. This seems to be a reasonable conclusion at first glance. However, because of NH2, one can’t just naively look at temperature ranges. We need to think about the changes in temperatures in light of changes in forcings because NH2 tells us we should expect the climate to respond in a similar way to forcings as it has in the past. So we need to look at what forcings are causing the temperature changes and then determine whether if humans are responsible for any of those forcings. We’re seeing increasing concentrations of CO2 and other GHGs in the atmosphere. We know that humans are causing an increase in atmospheric GHGs through the burning of fossil fuels and other practices (e.g., deforestation) – see Question 6 below for more detail. NH2 tells us that we should expect warming and indeed we do, though there is a lot of short-term variation in climate that can make it difficult to see the long-term trends.

So we’re left with two possibilities:

1. NH2 is no longer valid. The processes that have governed the earth’s climate throughout its history have suddenly starting working in a very different way than in the past.

Or

2. NH1 is no longer valid. Humans are indeed having an effect on climate.

Both of these things may seem difficult to believe. The question I would ask is: which is more unbelievable?

Question 4: Is the globe warming?

Willis calls this a trick question and makes the point that the question is meaningless with a time scale. He is correct of course that time scale is important. For NH2, the timescale is one in which the effects of changing forcings can been seen in the climate signals (i.e., where the “signal” of the forcings stands out against the short-term climate variations). For NH1, the relevant period is when humans began to possibly have a noticeable impact on climate. Basically we’re looking for an overall warming trend over an interval and at time-scales that one would expect to see the influence of anthropogenic GHGs.

Question 5: Are humans responsible for global warming?

Willis and I agree – the evidence indicates that the answer is yes.

Question 6: How are humans affecting the climate?

Willis mentions two things: land use and black carbon. These are indeed two ways humans are affecting climate. He mentions that our understanding of these two forcings is low. This is true. In fact the uncertainties are of the same order of as the possible effects, which make it quite difficult to tell what the ultimate impact on global climate these will have. However, Willis fails to directly mention the one forcing that we actually have good knowledge about and for which the uncertainties are much smaller (relative to the magnitude of the forcing): greenhouse gases (GHGs). This is because GHGs are, along with the sun and volcanoes, a primary component that regulates the earth’s climate on a global scale. It might be worth reviewing a few things:

1. Greenhouse gases warm the planet. This comes out of pretty basic radiative properties of the gases and has been known for well over 100 years.

2. Carbon dioxide is a greenhouse gas. This is has been also been known for well over 100 years. There are other greenhouse gases, e.g., methane, nitrous oxide, ozone, but carbon dioxide is the most widespread and longest-lived in the atmosphere so it is more relevant for long-term climate change.

3. The concentration of CO2 is closely linked with temperature – CO2 and temperature rise or fall largely in concert with each other. This has been observed in ice cores from around the world with some records dating back over 800,000 years. Sometimes the CO2 rise lags the temperature rise, as seems to be the case in some of ice ages, but this simply means that CO2 didn’t initiate the rise (it is clear that solar forcing did) and was a feedback. But regardless, without CO2 you don’t get swings between ice ages and interglacial periods. To paraphrase Richard Alley, a colleague at Penn State: “the climate history of the earth makes no sense unless you consider CO2”.

4. The amount of carbon dioxide (and other GHGs) has been increasing. This has been directly observed for over 50 years now. There is essentially no doubt as to the accuracy of these measurements.

5. The increase in CO2 is due to human emissions. There are two ways we know this. First, we know this simply through accounting – we can estimate how much CO2 is being emitted by our cars, coal plants, etc. and see if matches the observed increase in the atmosphere; indeed it does (after accounting for uptake from the oceans and biomass). Second, the carbon emitted by humans has a distinct chemical signature from natural carbon and we see that it is carbon with that human signature that is increasing and not the natural carbon.

6. Given the above points and NH2, one expects the observed temperature rise is largely due to CO2 and that increasing CO2 concentrations will cause temperatures to continue to rise over the long-term. This was first discussed well over 50 years ago.

If you’re interested in more details, I would recommend the CO2 page here: http://www.aip.org/history/climate/co2.htm, which is a supplement to Spencer Weart’s book, “The Discovery of Global Warming”.

Of course, there are other forcings so we don’t expect an exact match between temperatures and GHGs with a completely steady temperature increase. Periods of relatively cooler temperatures, more sea ice, etc. are still part of the natural variations of the climate system that continue to occur. Such periods may last for months or years. The anthropogenic GHG forcing is in addition to the natural forcings, it doesn’t supersede them. And of course, as with any scientific endeavor, there are uncertainties. We can’t give the precise amount warming one gets from a given amount of CO2 (and other GHGs) with 100% certainty; we make the best estimate we can based on the evidence we have. And that tells us that while there are uncertainties on the effect of GHGs, it is very unlikely the effect is negligible and the global effects are much larger than those of land use changes and soot.

Question 7: How much of the post-1980 temperature change is due to humans?

Here Willis says we get into murky waters and that there is little scientific agreement. And indeed this is true when discussing the factors he’s chosen to focus on: land use and soot. This is because, as mentioned above, the magnitudes of these forcings are small and the uncertainties relatively large. But there is broad scientific agreement that human-emitted CO2 has significantly contributed to the temperature change.

Question 8: Does the evidence from the climate models show that humans are responsible for changes in the climate?

Willis answers by claiming that climate models don’t provide evidence and that evidence is observable and measurable data about the real world. To me evidence is any type of information that helps one draw conclusions about a given question. In legal trials, it is not only hard physical evidence that is admitted, but information such as the state of mind of the defendant, motive, memories of eyewitnesses, etc. Such “evidence” may not have the same veracity as hard physical evidence, such as DNA, but nonetheless it can be useful.

Regardless, let me first say that I’m a data person, so I’ve always been a bit skeptical of models myself. We certainly can’t trust them to provide information with complete confidence. It may surprise some people, but most modelers recognize this. However, note that in my response to question 6 above, I never mention models in discussing the “evidence” for the influence of human-emitted CO2 on climate. So avoiding semantic issues, let me say that climate models are useful (though far from perfect) tools to help us understand the evidence for human and other influence on climate. And as imperfect as they may, they are the best tool we have to predict the future.

Question 9: Are the models capable of projecting climate changes for 100 years?

Based on Willis’ answer to Question 1, I’m surprised at his answer here. If the earth has a preferred temperature, which is actively maintained by the climate system, then it should be quite easy to project climate 100 years into the future. In Question 1, Willis proposed the type of well-behaved system that is well-suited for modeling.

However, Willis claims that such a projection is not possible because climate must be more complex than weather. How can a more complex situation be modeled more easily and accurately than a simpler situation? Let me answer that with a couple more questions:

1. You are given the opportunity to bet on a coin flip. Heads you win a million dollars. Tails you die. You are assured that it is a completely fair and unbiased coin. Would you take the bet? I certainly wouldn’t, as much as it’d be nice to have a million dollars.

2. You are given the opportunity to bet on 10000 coin flips. If heads comes up between 4000 and 6000 times, you win a million dollars. If heads comes up less than 4000 or more than 6000 times, you die. Again, you are assured that the coin is completely fair and unbiased. Would you take this bet? I think I would.

But wait a minute? How is this possible? A single coin flip is far simpler than 10000 coin flips. The answer of course is that what is complex and very uncertain on the small scale can actually be predictable within fairly narrow uncertainty bounds at larger scales. To try to predict the outcome of a single coin flip beyond 50% uncertainty, you would need to model: the initial force of the flip, the precise air conditions (density, etc.), along with a host of other things far too complex to do reasonably because, like the weather, there are many factors and their interactions are too complex. However, none of this information is really needed for the 10000 toss case because the influence of these factors tend to cancel each other out over the 10000 tosses and you’re left with a probabilistic question that is relatively easy to model. In truth, many physical systems are nearly impossible to model on small-scales, but become predictable to acceptable levels at larger scales.

Now of course, weather and climate are different than tossing a coin. Whereas coin flips are governed largely by statistical laws, weather and climate are mostly governed by physical laws. And climate models, as I mentioned above, are far from perfect. The relevant question is whether climate can be predicted at a high enough confidence level to be useful. As mentioned in NH2, we find that climate has largely varied predictably in response to past changes in forcing. This is clearly seen in ice core records that indicate a regular response to the change in solar forcing due to changes in the earth’s orbit (i.e., Milankovitch cycles). If climate were not generally predictable, we would expect the earth’s climate to go off into completely different states with each orbital change. But that doesn’t happen – the earth’s climate responds quite regularly to these cycles. Not perfectly of course – it is a complex system – but close enough that the uncertainties are low enough for us to make reasonable predictions.

It is worth mentioning here that while the general response of climate to forcing is steady and predictable, there is evidence for sudden shifts in climate from one regime to another. This doesn’t invalidate NH2, it merely suggests that there may be thresholds in the climate system that can be crossed where the climate transitions quickly into a new equilibrium. When exactly such a transition may occur is still not well known, which adds uncertainty suggest that impacts could come sooner and be more extreme than models suggest. On the other hand, as Willis mentions there may be stabilizing mechanisms that much such transitions less likely.

Finally, Willis says that climate model results are nothing more than the beliefs and prejudices of the programmers made tangible. But if Willis stands by his answer to Question 1 that the climate stays in preferred states, it should be very easy to create a new climate model, without those biases and prejudices, and show that humans aren’t having a significant effect on climate

Question 10: Are current climate theories capable of explaining the observations?

Willis answers no, but he doesn’t answering the question he poses. He instead discusses the climate sensitivity of to CO2 forcing, i.e., 3.7 Watts per square meters leads to a temperature change between 1.5 C and 4.5 C. These numbers are simply a quantitative estimate of NH2, with an associated uncertainty range. Not being able to narrow that range certainly indicates that we still have more to learn. But it’s important to note that as computing power has increased and as our understanding of the climate has increased over the past several decades that range hasn’t shifted much. It hasn’t gone to up to 6.5-9.5 C or down to -4.5 to -0.5 C. So this is further support for NH2. While perhaps we haven’t been able to narrow things down to the exact house in our neighborhood, we’ve gained increasing confidence that the hypothesis that we’re in the right neighborhood is correct.

But getting back to the question Willis posed. Yes, current climate theories are capable of explaining the observations – if one includes GHGs. Increasing GHGs should result in increasing temperatures and that is what we’ve observed. The match isn’t perfect of course, but nor should it expected to be. In addition to anthropogenic GHG forcing, there are other natural forcings still playing a role and there may things we’re not fully accounting for. For example, Arctic sea ice is declining much faster than most models have projected. Remember, where models are wrong does not necessarily provide comfort – things could ultimately be more extreme than models project (particularly if a threshold is crossed).

Question 11: Is the science settled?

This isn’t a particularly well-posed question, for which Willis is not to blame. What “science” are we talking about? If we’re talking about the exact sensitivity of climate to CO2 (and other GHGs), exactly what will be the temperature rise be in the next 100 years, what will happen to precipitation, what will be the regional and local impacts? Then no, the science is not even close to being settled. But if the question is “is NH2 still valid?”, then yes I would say the science is settled. And as a result, we also can say the science is settled with respect to the question: “have human-emitted GHGs had a discernable effect on climate and can we expect that effect to continue in the future?”

Question 12: Is climate science a physical science?

Willis answers “sort of” and that it is a “very strange science” because he defines climate as the “average of weather over a suitably long period of time” and that “statistics is one of the most important parts of climate science”. Our description of climate does indeed rely on statistics because they are useful tools to capture the processes that are too complex to explicitly examine. This is not unlike a lot of physical sciences, from chemistry to biology to quantum physics, which employ statistical approaches to describe processes that can’t be explicitly measured. But statistics are merely a tool. The guts of climate science are the interactions between elements of the climate system (land, ocean, atmosphere, cryosphere) and their response to forcings. This isn’t really all that different from many physical sciences.

Question 13: Is the current peer-review system inadequate, and if so how can it be improved?

There is always room for improvement and Willis makes some good suggestions in this regard. Speaking only from my experience, the process works reasonably well (though not perfectly), quality papers eventually get published and bad papers that slip through the peer-review process and get published can be addressed by future papers.

Question 14: Regarding climate, what action (if any) should we take at this point?

This is of course an economic and political question, not a scientific question, though the best scientific evidence we have can and should inform the answer. So far there isn’t any scientific evidence that refutes NH2 and we conclude that the processes that influenced climate in the past are doing so today and will continue to do so in the future. From this we conclude that humans are having an impact on climate and that this impact will become more significant in the future as we continue to increase GHGs in the atmosphere. Willis answers no and claims that the risks are too low to apply the precautionary principle. The basis for his answer, in practical terms, is his conclusion that NH2 is no longer valid because while GHGs have been a primary climate forcing throughout earth’s history, they are no longer having an impact. This could of course be true, but to me there doesn’t seem to be much evidence to support this idea. But then again, I’m a skeptic.

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I’m looking at the temperature record as read from this central Greenland ice core ( http://www.ncdc.noaa.gov/paleo/metadata/noaa-icecore-2475.html ). It gives us about as close as we can come to a direct, experimental measurement of temperature at that one spot for the past 50,000 years. As far as I know, the data are not adjusted according to any fancy computer climate model or anything else like that.

So what does it tell us about, say, the past 500 years? (the youngest datum is age=0.0951409 (thousand years before present) — perhaps younger snow doesn’t work so well?):

Well, whaddaya know — a hockey stick. In fact, the “blade” continues up in the 20th century at least another half a degree. But how long is the handle? How unprecedented is the current warming trend?

Yes, Virginia, there was a Medieval Warm Period, in central Greenland at any rate. But we knew that — that’s when the Vikings were naming it Greenland, after all. And the following Little Ice Age is what killed them off, and caused widespread crop failures (and the consequent burning of witches) across Europe. But was the MWP itself unusual?

Well, no — over the period of recorded history, the average temperature was about equal to the height of the MWP. Rises not only as high, but as rapid, as the current hockey stick blade have been the rule, not the exception.

In fact for the entire Holocene — the period over which, by some odd coincidence, humanity developed agriculture and civilization — the temperature has been higher than now, and the trend over the past 4000 years is a marked decline. From this perspective, it’s the LIA that was unusual, and the current warming trend simply represents a return to the mean. If it lasts.

From the perspective of the Holocene as a whole, our current hockeystick is beginning to look pretty dinky. By far the possibility I would worry about, if I were the worrying sort, would be the return to an ice age — since interglacials, over the past half million years or so, have tended to last only 10,000 years or so. And Ice ages are not conducive to agriculture.

… and ice ages have a better claim on being the natural state of Earth’s climate than interglacials. This next graph, for the longest period, we have to go to an Antarctic core (Vostok):

In other words, we’re pretty lucky to be here during this rare, warm period in climate history. But the broader lesson is, climate doesn’t stand still. It doesn’t even stand stay on the relatively constrained range of the last 10,000 years for more than about 10,000 years at a time.

Does this mean that CO2 isn’t a greenhouse gas? No.

Does it mean that it isn’t warming? No.

Does it mean that we shouldn’t develop clean, efficient technology that gets its energy elsewhere than burning fossil fuels? Of course not. We should do all those things for many reasons — but there’s plenty of time to do them the right way, by developing nanotech. (There’s plenty of money, too, but it’s all going to climate science at the moment. ) And that will be a very good thing to have done if we do fall back into an ice age, believe me.

For climate science it means that the Hockey Team climatologists’ insistence that human-emitted CO2 is the only thing that could account for the recent warming trend is probably poppycock.

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http://www2.ucar.edu/news/missing-heat-may-affect-future-climate-change

"Missing" heat may affect future climate change

April 15, 2010
BOULDER—Current observational tools cannot account for roughly half of the heat that is believed to have built up on Earth in recent years, according to a “Perspectives” article in this week’s issue of Science...

Satellite sensors show that the amount of greenhouse-trapped solar energy, or heat, has risen over recent years. But in the past decade, there has been a growing divergence between the satellite readings and ocean observations that indicate the build-up of heat is slowing. This "missing" heat could, in part, be the result of instrument error or incorrect data processing, but much of it may be going into the deep ocean or elsewhere on Earth that is beyond the reach of current sensors. This graph shows simplified estimates of the measurements of heat. (Courtesy Science).


...“Either the satellite observations are incorrect, says Trenberth, or, more likely, large amounts of heat are penetrating to regions that are not adequately measured, such as the deepest parts of the oceans. Compounding the problem, Earth’s surface temperatures have largely leveled off in recent years. Yet melting glaciers and Arctic sea ice, along with rising sea levels, indicate that heat is continuing to have profound effects on the planet.”

“A percentage of the missing heat could be illusory, the result of imprecise measurements by satellites and surface sensors or incorrect processing of data from those sensors, the authors say. Until 2003, the measured heat increase was consistent with computer model expectations. But a new set of ocean monitors since then has shown a steady decrease in the rate of oceanic heating, even as the satellite-measured imbalance between incoming and outgoing energy continues to grow.”...

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http://pielkeclimatesci.wordpress.c...ystem-my-comments-on-this-ncar-press-release/

...Trenberth’s [and co-author, NCAR scientist John Fasullo], however, are grasping for an explanation other than the actual real world implication of the absence of this heat.

First, if the heat was being sequestered deeper in the ocean (lower than about 700m), than we would have seen it transit through the upper ocean where the data coverage has been good since at least 2005. The other reservoirs where heat could be stored are closely monitored as well (e.g. continental ice) as well as being relatively small in comparison with the ocean.​

Second, the melting of glaciers and continental ice can be only a very small component of the heat change (e.g. see Table 1 in Levitus et al 2001 “Anthropogenic warming of Earth’s climate system”. Science).​

Thus, a large amount heat (measured as Joules) does not appear to be stored anywhere; it just is not there.
-Roger Pielke, Ph.D.

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...there are a few points and opinions I’d like to share.

1) THE MISSING ENERGY IS IN THE SOLAR, NOT THE INFRARED
Trenberth and Fasullo don’t highlight the fact that the “missing” energy is not in the infrared, which is where manmade global warming allegedly originates, but in the reflected solar component. The infrared component has essentially no trend between March 2000 and December 2007 (the last CERES Earth radiation budget data I have analyzed).

This suggests a small decrease in low or mid-level cloud cover, letting more sunlight in. The fact that the extra energy is not showing up as a temperature increase in the ocean makes me suspect the measurements themselves. If there is a problem with the Earth radiation budget measurements, then obviously there is no missing energy.

2) MAYBE THE DISCREPANCY WAS ACTUALLY BEFORE 2000
Trenberth and Fasullo correctly point out that the absolute accuracy of these radiation budget instruments is not good enough to measure very small radiation imbalances…just the CHANGE in that imbalance over time. Well then maybe it was the period BEFORE 2000 where there was an imbalance, with extra energy being lost by the Earth, but no cooling, and NOW the solar and infrared flows are once again in balance. Just a thought.

3) OCEAN TEMPERATURES ARE MUCH EASIER TO MEASURE THAN THE EARTH’S RADIATION BUDGET
Trenberth and Fasullo briefly acknowledge that there might be measurement errors involved here, and I would argue that this is much more likely in the Earth radiation budget measurements than in the ocean temperature measurements. The amount of solar energy the Earth absorbs is particularly difficult to measure because a monitoring satellite is only a single point in space, whereas the total amount of sunlight being reflected off clouds goes in all different directions.

Because of this complication, many detailed calculations must be made by the dataset developers to estimate the energy flows at all angles, based upon years of accumulated statistics with radiation budget instruments that measure some of the clouds at different angles. I think the dataset developers are doing the best they can with the available information, but what we are asking the data to reveal to us is a very small signal.

4) “YOU’VE LOST ANOTHER SUBMARINE”?
We have already been dealing with some missing global warming in the last 10 to 30 years, since 95% of the climate models suggest our carbon dioxide emissions should have caused more global warming than what has been observed — and that is due to an infrared effect. Now, we are told that there is missing SOLAR energy, too?

This reminds me of the 1990 movie, The Hunt for Red October. After an entire movie dealing with a missing experimental Soviet submarine, the end of the movie shows the Soviet Ambassador asking the U.S. to help find…what!?…ANOTHER missing submarine? It was a funny line.

I’m sorry, but at some point we need to ask whether all of this missing warming and energy are missing because they really do not exist. This is Roger Pielke, Sr.’s opinion, and at this point it is mine as well. Only time will tell.

-Roy W. Spencer, Ph.D.

http://www.drroyspencer.com/2010/04/some-comments-on-earth’s-“missing-energy”/

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trysail said:

Jomar,
Is there something you haven't been telling us?

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23/04/2010 14:33
Research for mineral resources in the Arctic may be hampered by a global trend towards colder weather rather than global warming, a Russian scientist said on Friday.

Prof. Oleg Pokrovsky of the Voeikov Main Geophysical Observatory (MGO) said the cold snap began in 1998 and the temperatures are predicted to return to the lows of the 1950s-1960s and reach their peak in 15 years.

Despite the predictions of global warming, which has been the greatest economic and political challenge, most parts of the world have recently seen widespread low temperatures and extremely heavy snowfalls.

"Now all the components of the climate system are entering the negative phase. Politicians who placed their bets on global warming may lose the pot," Pokrovsky said at a conference on marine research in the Polar regions.

The scientist explains the possible climate miscalculation by the fact that most meteorological stations in the United States are located in urban areas which are affected by the city's microclimate where the temperature is usually higher.

"We do not know everything that happens. The climate system is extremely complicated and the Intergovernmental Panel on Climate Change (IPCC) is not the highest authority," Pokrovsky said.

The scientist has warned, however, that global cooling could jeopardize the race of world powers for the largely unexplored mineral resources in the Arctic, which has recently intensified.

"The northern marine passage will freeze and it will be impossible to pass through it without icebreakers," Pokrovsky said. "I think the development of the shelf will face large problems," he added.

ST. PETERSBURG, April 23 (RIA Novosti)



http://en.rian.ru/Environment/20100423/158714403.html

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The amount of CO2 released from soils worldwide each year is estimated to be about 8-10 times greater than the amount released by humans.

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A large number of healthy people won't handle the heat if temperatures continue to increase into next century, predict researchers.

The study, which appears in the recent issue of Proceedings of the National Academy of Sciences, also suggests heat could affect more land mass than rising sea levels.

The human body maintains a constant core temperature of 98.6 degrees F (37 degrees C) by giving off excess heat through the skin. But, if the "web-bulb" temperature of the air reaches 95 degrees F (35 degrees C), this heat dissipation stops, causing the body to retain heat, resulting in heat stress.

Wet-bulb temperature is measured using a thermometer wrapped in a wet, porous material. It is typically less than "dry-bulb" temperature and is used to calculate humidity.

Steven Sherwood of University of New South Wales and Matthew Huber of Purdue University in Illinois, used climate models to predict where and when temperatures will increase to uncomfortable levels.

They found a global temperature increase of 10.8 degrees F (7 degrees C) above pre-industrial levels would push temperatures in some regions above 95 degrees F for extended periods, resulting in heat stress across the whole population. Sherwood said while heat-related deaths among the elderly and young already occur, global warming will result in more of the population suffering.

"What we're talking about here is something a bit different -- these limits apply to a healthy person," he said.

The study highlights a number of potential "hot spots" in the future.

"The places that heat stress will be highest are places near sea level and at lower latitudes and that's where people live," said Sherwood. "This includes Amazonia; most of China; India; Indonesia; pretty much all of South East Asia; eastern United States; northern Australia and parts of Africa."

Sherwood said populations faced with heat stress have two options -- relocate to a cooler climate or rely on air conditioning.

"Right now we have air conditioning for comfort," he said. "Under these circumstances you would be using it for survival."

The study also mentions the impact higher temperatures will have on livestock.

"You wouldn't be able to raise the usual levels of livestock unless you have them living in giant air conditioned domes," Sherwood said.

While the Earth has experienced similar levels of warming in the past, Sherwood said it is currently occurring on a much faster scale.

"The last warm period lasted for many millions of years and came on gradually," he said. "[Current warming] is not coming on gradually. Compared to other climates of this type it's more explosive."

Sherwood said a 10.8 degree F (7 degree C) increase isn't likely to happen until next century, but he said it's important to understand the impact should it occur.

"When you're planning sensibly for anything you plan for the worst case scenario," he said. "We're saying this is the worst scenario, we're not saying it's going to happen soon, but to ignore it seems foolhardy."

The researchers conclude further warming would have a more drastic impact.

"If warmings of 10.8 degrees F (10 degrees C) were really to occur in [the] next three centuries, the area of land likely rendered uninhabitable by heat stress would dwarf that effect by rising sea level," they write.

The average global temperature has increased by 1.4 degrees F (0.8 degrees C) since pre-industrial times. Some scientists and environmental groups are pushing for limits on human-produced greenhouse gas emissions to limit the increase to no more than 3.6 degrees F (2 degrees C).

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The UK's Royal Society is reviewing its public statements on climate change after 43 Fellows complained that it had oversimplified its messages.

They said the communications did not properly distinguish between what was widely agreed on climate science and what is not fully understood...


...One Fellow who said he was not absolutely convinced of the dangers of CO2 told me: “This appears to suggest that anyone who questions climate science is malicious. But in science everything is there to be questioned – that should be the very essence of the Royal Society. Some of us were very upset about that.

“I can understand why this has happened – there is so much politically and economically riding on climate science that the society would find it very hard to say ‘well, we are still fairly sure that greenhouse gases are changing the climate’ but the politicians simply wouldn’t accept that level of honest doubt.”

Another society protester said he wanted to be called a climate agnostic rather than a sceptic. He said he wanted the society’s website to “do more to question the accuracy of the science on climate feedbacks” (in which a warming world is believed to make itself warmer still through natural processes).

“We sent an e-mail round our friends, mainly in physical sciences,” he said.

“Then when we had got 43 names we approached the council in January asking for the website entry on climate to be re-written. I don’t think they were very pleased. I don’t think this sort of thing has been done before in the history of the society.

“But we won the day, and the work is underway to re-write it. I am very hopeful that we will find a form of words on which we can agree.

“I know it looks like a tiny fraction of the total membership (1,314) but remember we only emailed our friends – we didn’t raise a general petition.”





http://news.bbc.co.uk/2/hi/science_and_environment/10178124.stm

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