About that scientific consensus…

February 27, 2010

The British Parliament has begun an investigation into the meaning of the East Anglia CRU e-mails, and part of that process is a form of peer review, in a sense.  Their Science and Technology committee has welcomed commentary from the scientific community, and among those members is the non-profit charity, the Institute of PhysicsIn their submission, the IoP says that the UEA CRU e-mails don’t just indict East Anglia, but the entire AGW industry — and that “science” wasn’t what they were doing at all (via Watts Up With That and Mike Ross, emphases mine):

What are the implications of the disclosures for the integrity of scientific research?

1. The Institute is concerned that, unless the disclosed e-mails are proved to be forgeries or adaptations, worrying implications arise for the integrity of scientific research in this field and for the credibility of the scientific method as practised in this context.

2. The CRU e-mails as published on the internet provide prima facie evidence of determined and co-ordinated refusals to comply with honourable scientific traditions and freedom of information law. The principle that scientists should be willing to expose their ideas and results to independent testing and replication by others, which requires the open exchange of data, procedures and materials, is vital. The lack of compliance has been confirmed by the findings of the Information Commissioner. This extends well beyond the CRU itself – most of the e-mails were exchanged with researchers in a number of other international institutions who are also involved in the formulation of the IPCC’s conclusions on climate change.

And as far as the science being settled, or even “science” as understood by the public as conclusory data, the IoP has issues with that characterization as well:

4. The second category relating to proxy reconstructions are the basis for the conclusion that 20th century warming is unprecedented. Published reconstructions may represent only a part of the raw data available and may be sensitive to the choices made and the statistical techniques used. Different choices, omissions or statistical processes may lead to different conclusions. This possibility was evidently the reason behind some of the (rejected) requests for further information.

5. The e-mails reveal doubts as to the reliability of some of the reconstructions and raise questions as to the way in which they have been represented; for example, the apparent suppression, in graphics widely used by the IPCC, of proxy results for recent decades that do not agree with contemporary instrumental temperature measurements.

In other words, the claims made by AGW advocates didn’t match the data available elsewhere.  When challenged on this, the AGW advocates refused to release the data to other scientists, and finally refused to release it under a Freedom of Information demand.  When it looked as though the government would get their hands on the data anyway, the CRU conspired to destroy the data, along with other AGW advocates around the world.

The IoP doesn’t trust East Anglia to restore confidence in the AGW movement’s claim to science, either, because the fraud went well beyond the boundaries of the University of East Anglia:

Are the terms of reference and scope of the Independent Review announced on 3 December 2009 by UEA adequate?

10. The scope of the UEA review is, not inappropriately, restricted to the allegations of scientific malpractice and evasion of the Freedom of Information Act at the CRU. However, most of the e-mails were exchanged with researchers in a number of other leading institutions involved in the formulation of the IPCC’s conclusions on climate change. In so far as those scientists were complicit in the alleged scientific malpractices, there is need for a wider inquiry into the integrity of the scientific process in this field.

11. The first of the review’s terms of reference is limited to: “…manipulation or suppression of data which is at odds with acceptable scientific practice…” The term ‘acceptable’ is not defined and might better be replaced with ‘objective’.

12. The second of the review’s terms of reference should extend beyond reviewing the CRU’s policies and practices to whether these have been breached by individuals, particularly in respect of other kinds of departure from objective scientific practice, for example, manipulation of the publication and peer review system or allowing pre-formed conclusions to override scientific objectivity.

Excerpt from here.

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The heart of the matter: those CRU files!

November 24, 2009

This letter to Andy Revkin of the New Times, DotEarth, is an excellent statement of the genuine issues raised by the CRU “hacked” emails.  The issues are serious.  Highlighting is by me.  I found this text at Jeff Id’s blog, The Air Vent, but it is linked in many places.

Oh, and if you want to jump to a really juicy email instead of reading this long letter, check out this one.  Seems they weren’t so confident in their long-term projections after all, nor in their repeated denials (are they the denialists?) that the models had failed to predict a current sustained stalling of temperature rise.

~~~~~~~~~~~~~~~~~~~ * ~~~~~~~~~~~~~~~~~~~~~

Dear Mr. Revkin,

I am writing to you to express my concerns with the content of the emails and documents that were recently obtained and released from the University of East Anglia. In my opinion, many of the comments in the blog articles about this incident have taken extreme positions that cloud the importance of the information that is contained in the documents and emails. With that in mind, I would like to take a moment to describe what I feel are the critical lessons that can be learned from this incident.

So that you understand my perspective, I have been labeled as a climate change skeptic, a contrarian, anti-science, and denialist. I have been referred to in a derogatory fashion (and have even been the subject of an entire, somewhat condescending post on RealClimate concerning analyses I had done on the Steig Antarctica paper) because I have questioned the results of several influential articles on climate change. I feel these characterizations are unfair, as I believe that humanity is contributing in a meaningful fashion to the observed rise in global surface air temperatures. I have witnessed several of my contemporaries being labeled in similar fashion in spite of the fact that they, too, believe the same.

 This illustrates the polarization of the climate change debate that is a dangerous impediment to the science. It appears that unless one believes that catastrophic consequences will necessarily result unless a certain set of draconian measures are taken, that one is dismissed as a crackpot, a liar, and is insinuated or directly accused of having been paid off by corporate interests. This produces a destructive environment for discussing the science of climate change.

As a skeptic, I can say in no uncertain terms that the emails and documents from the University of East Anglia do not show that AGW is a falsehood or hoax. Claims that “global warming is dead” (as I have seen) are not supported by those documents. On the other hand, claims that “the science is settled” are shown to be an exaggeration.

While vocal skeptics such as Steve McIntyre have been vilified by several influential scientists, the content of the emails demonstrate quite clearly that many of the concerns were legitimate and that this was known by the scientists who repeatedly and publicly denied the veracity of those claims. These include, but are not limited to:

· The concern that the significance statistics for MBH 98 were benchmarked to an inappropriate type of noise. Despite public claims to the contrary, Dr. Mann states clearly in email 1059664704.txt that the calibration residuals were “significantly red” for at least two cases. This validates the McIntyre & McKitrick criticism that the confidence intervals and benchmark significance statistics were incorrectly calculated and that MBH claimed greater statistical significance for their reconstruction than was supported by the data.

· The concern that the WMO 1999 main graphic, MBH 98, and several other reconstructions included in the IPCC spaghetti graphs had inappropriately spliced instrumental temperatures onto the end of the reconstructions. Despite Dr. Mann publicly stating that “No researchers in this field have ever, to our knowledge, ‘grafted the thermometer record onto’ any reconstrution. It is somewhat disappointing to find this specious claim (which we usually find originating from industry-funded climate disinformation websites) appearing in this forum,” on RealClimate, it is quite clear that this is exactly what was done in emails 0966015630.txt and 0942777075.txt.

· The concern that without either stripbark foxtails, bristlecones and/or the Yamal chronology that the hockey stick shape in the 20th century was greatly reduced. Despite pre-publication discussion and disclosure of review comments of the Wahl & Ammann and Ammann & Wahl defenses of MBH in which the McIntyre and McKitrick claims were dismissed as “total crap”, none of these individuals checked WA and AW closely enough to see that they performed not a single reconstructions that did not include at least one of the offending chronologies. They also express concerns that there are methodological problems with MBH, but were more concerned with defending MBH than disclosing factors that they know may partially undermine the result or increase the uncertainty of the result. This may be seen in emails 1102956446.txt, 1108248246.txt, 1122669035.txt, and others.

· The concern that the Yamal selection used in Kaufman 2009 and other papers was only a subset and, if the full chronology is used, that the answer changes in a non-trivial fashion. In a string of emails, it can be seen how several of the most influential scientists begin discrediting this concern before they had even researched the claim to see if it is legitimate. As it turns out, it is a legitimate concern, though claims of fraud by some bloggers do not seem substantiated. Rather, confirmation bias seems far more likely. These are in emails 1256760240.txt, 1256735067.txt, 1254756944.txt, and others.

As you may be aware, this is only a partial list.

These serve to illustrate not that the scientists involved are engaged in fraudulent behavior for personal gain, but rather that they feel that it is their right or duty to be the gatekeepers of what information is allowed to be seen. I think it is clear that the scientists believe that they are correct. I think it is clear that they use this belief to justify actively engage in censoring their own results (and pressure others to censor theirs) to prevent full disclosure of the uncertainties involved in the methods they employ. I think it is clear that they use this belief to justify attempts to discredit legitimate criticisms, in some cases with the knowledge that those criticisms are accurate. I think it is clear that they use this belief to advocate suppressing free expression on the internet. I think it is clear that they use this belief to attempt to manipulate the peer review process to present their results in a way that lends more credibility to their conclusions than otherwise would be the case. This is advocacy, not science. It in no way invalidates AGW theory, but it does call into question the certainty with which these scientists claim to understand the magnitude of the AGW effect – and, by extension, the magnitude and timing of the anticipated consequences.

This naturally leads into another important lesson: the insular nature of this relatively small, yet incredibly influential, group of scientists leads them to believe that it is their right to decide who should be privy to data and code. As a party to several of the FOIA requests of the University of East Anglia and CRU, I find myself appalled at the cavalier manner in which several key individuals handled FOIA requests. Some of the most telling emails are 1106338806.txt, 1212009215.txt, 1212063122.txt, 1214229243.txt, 1219239172.txt, and 1228412429.txt (among others) which indicate coordinated activities to prevent release of the data due to who was requesting it rather than the legitimacy of the request, to delete or destroy relevant data, and collusion with the FOIA officers to deny requests without properly examining whether the request was legitimate. While I do not believe that this activity should result in any kind of criminal prosecution whatsoever, I do believe that it should result in some form of corrective and/or disciplinary action by the appropriate institutions.

It is my hope that the above issues, not the unsubstantiated claims that AGW is “dead” or AGW is a “hoax”, are the issues that have traction. Otherwise, it is possible that these irresponsible claims – which are easily dismissed – will drown out the very real need for reforms to make climate science more open and accessible. Conversely, it is possible that these irresponsible claims could derail grants for additional research and damage support for many important mitigation activities that to this point were seen as not controversial (such as increased recycling efforts, development and increased commercialization of alternative energy, and similar efforts).

This letter is not intended for you to publish (though you may, as long as you do not quote it out of context). It is intended to provide you with a perspective from a “skeptic” who feels that the important lessons of this incident have not been well-carried by either the blogs or the media coverage. I write to you specifically because, although we may differ in our opinion of whether AGW is a presently a “crisis” and what the ideal mitigation/prevention activities might be, I have read enough of your column to believe that you are honest and forthright, and that you welcome hearing multiple sides of the climate debate. I enjoy your work (even when I disagree with your conclusions) and wish you continued success.

“Ryan O”


Those climate models…

November 22, 2009

Finding out what's in the black box!

I often wonder why the global warming doom-gloom-soothsayers have so much traction in the world.  Like right wing conservatives, they like to claim that they are victimized by a hostile establishment press, but the NYTimes, a pillar of the establishment, is certainly with them.  Check out the 230 comments on Andy Revkins DotEarth blog regarding the recent email disclosures from the CRU.  The Editors’ Selections, with the purpose of

…highlighting the most interesting and thoughtful comments representing a range of views.

includes 4 posts, all firmly in the camp of “How dare they publish this!  This is just normal science. Face it, global warming is a fact!!” So much for a range of views…but no matter.

But why do intelligent and scientifically literate people, including some who are quite reasonable, e.g., Andy Revkin, feel so confident that the AGW hypothesis has been established beyond doubt?  Frequently – check out those Selections – references are made to mountains, avalanches, piles…etc. of data that prove the point.  I think something is missing here:  I think it is the global circulation models (GCM) run on super computers that clinch it.  But there is very little peeking into those models – they are essentially a black box for most people:  numbers go in, Apocalypse comes out!

Without the models, there would be no terrifying scenarios, disturbing graphs showing steeply rising temperatures over decades to come, no tipping point doomsday model runs.  There would be some hard data (CO2 rising), a mountain of ice core, satellite, and surface data from which some would infer a clear trend, correlation, and causal mechanism;  there would be an interesting hypothesis about positive feedback amplifying the otherwise manageable temperature rise that might be caused by CO2 increases and that might or might not happen; there would be the same endless scientific haggling and argument over the way the numbers are handled by statistical routines and whether this or that presentation of the data is appropriate and meaningful; there would be no consensus.  The advocates of AGW would be a determined and inventive bunch, but they would be hard pressed to demonstrate that the rest of the world should abandon the null-hypothesis, i.e., climate and CO2 have always fluctuated- what’s so different now? –  and adopt their hypothesis.  Computer models change all that.

The GCMs give the AGW crowd the cover to say that they can predict (not with certainty, of course…) the future trend of the climate.  It gives them the supposed justification for stating that they have uncovered the “forcing function” that precisely quantifies the impact of CO2 concentrations on the climate.  It provides them with a rationale for assserting that their understanding of feedback mechanisms is corrrect and that their predictions are reliable.  This role of computer models is not often examined, rarely questioned, certainly not in the popular press.

It’s worth taking a look at the writing of Daniel Botkin, a scientist who was present at the creation of computer modeling in ecology, and who has a lot to say on the role of models in scientific investigations.  His basic point is that models are valuable tools for understanding a natural system, for trying out ideas of how changes in one thing may affect another, but they are not very good for making predictions.  His essay, Science and Soothsaying, is a good starting point.

Another critical view of computer modeling is the Pilkeys’ book Useless Arithmetic.  Orin Pilkey (not to be confused with the climate scientists father and son, Pielke Sr. and Pielke Jr., also with a jaundiced view of modelers’ work) is most known for his controversy with the US Army Corps over its penchant for pouring millions of dollars into pouring sand on eroding beaches.  These wasteful projects are often supported by very impressive computer modeling.

In thinking about this topic, I keep returning to a book published almost twenty years ago, Ice Time.  In its chapter, The Machine’s Eye, the author makes the point that the study of climate had become, in large part, the study of climate models.   He traces the rise of supercomputing in the investigation of climate, and notes that it has become “big business.”   The author is relatively uncritical of the use of the models, but he focuses more on their use to understand the mechanics of the climate system rather than to predict the future.  The chapter is the only extended discussion in layman terms that I have ever seen of just what computer models of the climate do, and how they are put together.  For that, it remains a very useful discussion.

Late Note on Revkin’s Blog:
Here’s some interesting comments following the controversy-click the number for link to full text
:

From a physicist who values scientific culture:   265. Frederick  UK

November 22nd, 2009
2:48 pm

… I cannot say whether AGW is a valid theory…What I can say is that Mann & co. have so undermined the scientific process that their results lack credibility. This has been a dark period for science. It seems that politics and science do not mix.

We need to put this behind us and get serious scientists who are not afraid to have their methods and results questioned. At the end of the day, there is nothing more convincing than facts and proper results. We need transparency but what we have here is a travesty!

From a true believer distressed at Andy Revkin’s lack of faith:  269. Wayne Hamilton Springdale, UT

November 22nd, 2009
2:48 pm
Your Dot Earth blog has changed since I started reading and contributing several years ago … I thought it functioned very effectively in describing the threat of anthropogenic climate change.But in recent months… you’ve become increasingly even-handed in balancing the opinions of AGW skeptics and proponents… You now seem to give equal time and credence to the knowledgeable and to the ignorant.
I’m sorry to report that your latest article on the CRU hacking gave me the impression that you no longer believe in the consensus of international science and the importance of that fact. It makes me sad to say this, but I’m no longer interested in following your Dot Earth blog. Good bye.

Also this one, with a potent warning for Revkin that goes to the heart of “he said, she said” journalism (emphasis added)261 John M.   San Francisco

November 22nd, 2009
2:48 pm

Hi Andy,

Comparing your NYT article on the controversy to the raw data, I find you are slanting the story, minimizing it, acting more like a press agent than an independent, hard-driving reporter. For example, you write:

“Some skeptics asserted Friday that the correspondence revealed an effort to withhold scientific information.”

The emails themselves clearly reveal an effort to withhold information, but you are describing this only as an assertion by skeptics.

Your article makes no mention at all of the obvious, and possibly illegal, effort to evade requests made under UK Freedom of Information laws.

A far better analysis can be found here: http://www.powerlineblog.com…

Andy, you are risking your credibility here.

John M.


Is Terra Burning…and how do we know?

March 20, 2009

bosch_burning

I’m feeling like a crank, but somebody’s got to do this dirty job…

I just read Chapter 4 of this book,  Climate Change: What It Means for Us, Our Children, and Our Grandchildren. The chapter I read is called “The Scientific Consensus on Climate Change:  How Do We Know We’re Not Wrong?” and it’s by Naomi Oreskes.  Professor Oreskes is now well known for an essay she published in Science in which she described the results of a survey of nearly 1000 scientific papers, and concluded that the consensus was clearly on the side of global warming being caused by human industrial activity.  To quote her university profile page:

Her 2004 essay “The Scientific Consensus on Climate Change” (Science 306: 1686), led to Op-Ed pieces in the Washington Post, the San Francisco Chronicle, and the Los Angeles Times, and has been widely cited in the mass media, including National Public Radio (Fresh Air), The New Yorker, USA Today, Parade, as well as in the Royal Society’s publication, “A guide to facts and fictions about climate change,” and, most recently, in Al Gore’s movie, “An Inconvenient Truth.”

The notion of an established consensus on anthropogenic global warming (AGW) especially one established by survey, always struck me as dubious.  I have read only the abstract of her survey paper, but Chapter 4 restates her work and also addresses general questions about the sociology and philosophy of scientific knowledge.  Her reasoning, I believe, is grossly superficial, and obviously influenced by her bias in favor of AGW.  I have to do this, point by point, here we go…italics and emphasis all mine.

Scientists glean their colleagues’ conclusions by reading their results in published scientific literature, listening to presentations at scientific conferences, and discussing data and ideas in the hallways of conference centers, university departments, research institutes, and government agencies. …

Climate science is a little different. Because of the political importance of the topic, scientists have been unusually motivated to explain their research results in accessible ways, and explicit statements of the state of scientific knowledge are easy to find.

“A little different” is a colossal understatement.  The debate has been heavily political because the supporters of AGW advocate far reaching economic changes.  (It happens that I agree with many of their proposals!)  The nature of the debate has been formed also by the circumstance that it isn’t possible to do killer confirmatory experiments to settle the issue and because so much of the base data is disputable in various ways.  Many discussions devolve into debates over statistical methodology.

The IPCC is an unusual scientific organization: it was created not to foster new research but to compile and assess existing knowledge on a politically charged issue. Perhaps its conclusions have been skewed by these political concerns, but the IPCC is by no means alone it its conclusions, and its results have been repeatedly ratified by other scientific organizations.

The question is ratified how, and by whom?  Could not these other organizations have similar biases?  Morever, statements issued by organizations in support of AGW are given much weight in the media, while petitions and letters signed by dissenters are treated as fringe efforts.

These kinds of reports and statements are drafted through a careful process involving many opportunities for comment, criticism, and revision, so it is unlikely that they would diverge greatly from the opinions of the societies’ memberships. Nevertheless, it could be the case that they downplay dissenting opinions. [note 2]

This does not fit with my knowledge of how organizations function.  Usually, there is a small group of very active people.  It is quite possible that the editorial arms of such professional groups have been ‘captured’ by AGW advocates.  In fact, in her note, Oreskes admits as much, using the Catholic Church as an example.  The views of the priests and the laity are often contradictory.

oreskes_graph

Here is the graphed output from Oreskes’ survey.  She is not particularly disturbed by the fact that no papers at all were discovered that denied/refuted the AGW “consensus,” not a one!

Under the category of Impacts she collects papers that discuss the “potential…or actual impacts” of warming.  Of course, if a paper (I have read several such) begins with the phrase, “Many experts predict warming over the next N years of X magnitude…” and then goes on to assess the ramifications of this speculative change, is this an “endorsement” of the AGW hypothesis?  Does the fact that nobody writes papers about the likely effects of no AGW indicate that nobody thinks the theory is bad?  Of course not!  There wouldn’t be anything to write about!  People who think it will happen as predicted are concerned, and write papers about it.  It also is a handy way to churn out papers in the publish-or-perish mill.  You don’t have to prove anything, just suppose…Similarly, papers that deal with the observed effects of climate change don’t necessarily prove anything about why it is changing.  Oreskes takes the opposite view – all these papers endorse the consensus.

[Note:  We know now that the process of peer review was strongly influenced  by politics  – see my posts on the release of emails called ‘Climategate’.  6/4/11]

She also neglects the obvious fact that people who think AGW is a worthless notion will not write papers about this.  What is there to investigate?  People who regard it as plausible but have doubts are in the same position.  Morever, if they are serious scientists, they want to write about their discipline, which may or may not be relevant to the debate, but their priority is to make defensible scientific claims.  Thus, there is quite possibly a vast reservoir of skepticism out there that is missed by her survey.

More…

Second, to say that global warming is real and happening now is not the same as agreeing about what will happen in the future. Much of the continuing debate in the scientific community involves the likely rate of future change.

So, of what does this consensus consist? If we agree that warming is happening now (and not everyone agrees) but we don’t agree on what will happen in the future, how do we have a consensus on the direction of climate change under the influence of human activity?  All scientists agree on the reality of climate change, but that is very different than saying they agree on AGW.

Third, there is the question of what kind of dissent still exists. … The total number of papers published over the last ten years having anything at all to do with climate change is probably over ten thousand, and no  doubt some of the authors of the other over nine thousand papers have expressed skeptical or dissenting views. But the fact that the sample turned up no dissenting papers at all demonstrates that any remaining professional dissent is now exceedingly minor.

This might have something to do with the fact that global circulation models (GCMs) are not falsifiable, not subject to controlled experiments, a point which Oreskes treats later on.  If they were, there would be clear target at which critics could aim.  In cases where critics have attempted to directly contradict specific AGW claims, e.g., the Hockey Stick controversy, their arguments, if accepted, are dismissed as unimportant.  How do you write a dissenting scientific paper about a point of view that you think is simply indefensible?

On the media war…

This suggests something discussed elsewhere in this book—that the mass media have paid a great deal of attention to a handful of dissenters in a manner that is greatly disproportionate with their representation in the scientific ommunity.

…they [contrarians] do no new scientific research. They are not producing new evidence or new  arguments. They are simply attacking the work of others and  mostly doing so in the court of public opinion and in the mass media rather than in the halls of science.  This latter point is crucial and merits underscoring: the vast majority of materials denying the reality of global warming do not pass the most basic test for what it takes to be counted as scientific…

There certainly are rabid and irresponsible kooks in the anti-AGW camp.  Of course, the last sentence quoted above would apply equally well to the pro-AGW materials.  I would say that Al Gore’s statements fit in there well.  This text was written in 2007, so I find Oreskes’ lamenting of the media attitude to be puzzling.  My sense is that the mass-media are firmly in the AGW camp, and are condescending and dismissive of opposing views, except in outlets that target a libertarian or right-wing political demographic.  Finally, it needs to be pointed out that to be a good critic of the basic assumptions and methodologies of the AGW camp, you don’t need to be doing new research:  you need to have a good understanding of modern science.

At this point, Oreskes switches gears and become more philosophical in a section called “How Do We Know We’re Not Wrong?”  Always a good question to ask.  She begins by reviewing the nature of science, and inductive and deductive reasoning.  Then this:

How does climate science stand up to the inductive model? Does climate science rest on a strong inductive base? Yes.  Humans have been making temperature records consistently for over 150 years, and nearly all scientists who have looked carefully at these records see an overall increase since the industrial revolution about 0.6 to 0.7 deg C… The empirical signal is clear, even if not all the details are clear.

Either there is a clear signal, or there is not.  What does it mean to say that the signal is clear, but the details aren’t?  Isn’t that where the devil is?

How reliable are the early records?  How do you average the data to be representative of the globe as a whole, even though much of the early data comes from only a few places, mostly in Europe?  Scientists have spent quite a bit of time addressing these questions; most have satisfied themselves that the empirical signal is clear.

Of course, this is the nub of so much of the debate, and she skates over it blithely.  Scientists who support the AGW position have convinced themselves, others have not…She goes on to assert that doubts about the older temperature records are not important because the recent, most significant increases in temperature are correlated with the recent upsurge of CO2.  But…but…if the historical record is not as the AGW people would have it, then the historical relationship of CO2 and temperature is not either, and that calls into doubt the contemporary relationship of the two.  So the recent upsurge of both, if it is real on the temperature side, might be due to other causes.

On deductive reasoning:

How does climate science stand up to this standard? Have climate scientists made predictions that have come true? AbsolutelyThe most obvious is the fact of global warming itself. As already has been noted in previous chapters, scientific concern over the effects of increased atmospheric carbon dioxide is based on physics—the fact that CO2 is a greenhouse gas.

Wow, this one is a howler!  Nobody denies the warm blanket effect of CO2 – the question is how that functions in the complex climate system of planet Earth.  Her formulation begs the question entirely.  If one assumes that natural variation is the cause of the putative currrent warming, then the fact of warming proves nothing about AGW.  And, of course, Nostradamus predicted things, or so people say, that have come about too.

Professor Oreskes is no slouch – she goes on to squarely face the Popper Question:  How does one falsify the AGW point of view?

How does climate science hold up to this modification?  Can climate models be refuted? Falsification is a bit of a problem for all models—not just climate models—because many models are built to forecast the future and the results will not be known for some time.

…calibration can make models refutation-proof: the model doesn’t get rejected; it gets revised.

A bit of  understatement there, about falsification.  Yes, models don’t get rejected, they get tweaked until they give the proper results.  She says that modelers get around this by running many models, ensembles, and comparing the results.  They all show warming – only the tempo and mode vary.  But what if the basic assumptions of all the models are wrong?

Is it possible that all these model runs are wrong? Yes,because they are variations on a theme. If the basic model conceptualization was wrong in some way, then all the models runs would be wrong. Perhaps there is a negative feedback loop that we have not yet recognized. … This is one reason that continued scientific investigation is warranted. But note that Svante Arrhenius and Guy Callendar predicted global warming before anyone ever built a global circulation model (or even had a digital computer). Climate models give us a tool for exploring scenarios and interactions, but you don’t need a climate  model to know that global warming is a real problem.

Oreskes answers her excellent question here with a monumental non sequitur.  The fact that Arrhenius made his predictions long ago does nothing to validate the content of the models.  His predictions were, I believe, for much more warming than is even claimed today.  Her final statement amounts to using her argument as conclusion to support her argument, and recalls to mind an editorial in the NYTimes from a while back.

Finally, we come to this:

Should we believe that the global increase in atmospheric carbon dioxide has had a negligible effect even though basic physics indicates otherwise?  Should we believe that the correlation between increased CO2 and increased temperature is just a weird coincidence? If there were no theoretical reason to relate them and if Arrhenius, Callendar, Suess, and Revelle had not predicted that all this would all happen, then one might well conclude that rising CO2 and rising temperature were merely coincidental. But we have every reason to believe that there is a causal connection and no good reason to believe that it is a coincidence. Indeed, the only reason we might think otherwise is to avoid committing to action: if this is just a natural cycle in which humans have played no role, then maybe global warming will go away on its own in due course.

And that sums up the problem. To deny that global warming is real is precisely to deny that humans have become geological agents, changing the most basic physical processes of the earth.

In her summing up, Oreskes brings up basic physics again.  Again, not the issue.  The issue is feedbacks in a complex system.  And the nature of the basic facts on the ground.  Weird coincidence?  The only thing that makes it weird is the predisposition to accept AGW.  Of course, she mixes political with scientific argument by assuming that all critics are against doing anything to address human impacts on the environment – I’m not.  To end, many people think that humans have become significant agents for change on the earth – this is not a new idea.  Criticizing AGW doesn’t have much to do with that position.

And by the way, in case any readers are wondering where I stand: the earth is round, and the Holocaust did happen.