Category Archives: Global warming

Yes, there is a strong consensus on climate change

I have been corresponding about these matters with one of the authors (Dana Nuccitelli) of the lead paper on the subject ( Cook et al. 2013 “Quantifying the consensus on anthropogenic global warming in the scientific literature“) for some years.

Arctic Sea Ice Volume, from Polar Science Center (

Climate change denial shares many interesting features of evolution denial. Misrepresentation of data, accusations of fraud (remember Climategate?), allegations of non-existent scientific disagreement, reporting on genuine scientific debates about rates and mechanisms as if they were fundamental disagreements of principle, and repeated attempts (especially in the US, at state level) to pass laws requiring schools to “teach the controversy”. In the US, although not as far as I know in the UK, there is strong overlap between evolution denial and climate change denial, both being linked to the Evangelical Right that has more or less captured the Republican Party. In both cases, there are Orwellian mislabellings. Thus the Cornwall Alliance for the Stewardship of Creation is dedicated to the unrestricted exploitation of the planet’s resources, while Evolution News and Views consists of nothing but attacks on the science that supports evolution. We also have the endless and shameless repetition of blatant falsehoods. Creationists keep on telling us that evolution has never been observed, that the fossil record is too sparse to be interpreted, and that there is a “missing link” between humans and their common ancestors with other apes. Climate change deniers seem oblivious to the massive loss of Arctic ice, while trumpeting every intermittent uptick as a major recovery, and use the then unique 1998 spike (exceeded several times since) as if it were an appropriate baseline. Other climate denial falsehoods that refuse to go away include the allegations (repeated on UK TV Channel 4 and elsewhere) that volcanoes emit more carbon dioxide than humans (the reverse is true, by a factor of over 100), and that present warming is due to Milankovich cycles (no; it is much too fast for that). Both have their own glossy websites, and setting up counters to these (such as talkorigins and pandasthumb for evolution, and Skeptical Science for climatology) is a major cottage industry.

Climate change denialists, however, take quote mining and misattribution to a whole new level. Thus denialists regularly accuse climate scientists of having switched from talking about global warming to talking about climate change or vice versa because the case for warming was so weak or because global warming sounds more frightening (versions vary). In reality, it was the denialist Frank Luntz who proposed the change in vocabulary, in an internal thinktank memo leaked to Mother Jones:

It’s time for us to start talking about “climate change” instead of global warming and “conservation ” instead of preservation. “Climate change’’ is less frightening than “global warming”

(In this memo, Luntz shows mastery of how to use words for effect; we would do well to study his methods closely.) And while both kinds of denialists accuse the scientists they are attacking of wholesale fraud, at least the evolution denialists do have one real case they can cite (Piltdown Man), while despite half a dozen investigations in two continents into alleged misconduct, the climate denialists have none.

There are two other important differences. One is scale of funding. The funding available to promote climate change denial is major, large enough to finance attempts to set up an entire bogus curriculum. The other is potential impact. If large numbers of people persist in a creationist view of reality, remaining obstinately misinformed about what kind of universe we inhabit and what kind of creatures we are, that is an enormous pity but has no obvious further implications. But if large numbers of voters, especially in the US, persist in denying our influence on climate, the implications for policy making are very serious indeed.

The Logic of Science

Even if you have never paid any real attention to the climate change “debate,” you have probably seen someone say that, “97% of climatologists agree that we are causing climate change.” This is a number that I have personally cited on numerous occasions, and it is a number that is highly contested by the climate change deniers. Indeed, I rarely mention the consensus without people responding by adamantly proclaiming that the 97% number is a myth, and the study that produced it (Cook et al. 2013) has been debunked. Therefore, in this post, I want to deal with the consensus on climate change from several angles. First, I want to focus on the prominent Cook et al. study and explain what the authors actually did, what they found, and why their study was robust. I also want to deal with some of the common criticisms of their study. Finally, I…

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Darwin, Agassiz, and Global Warming; The Case of the Vanishing Lake

Darwin thought the parallel “Roads” of Glen Roy represented vanished marine shorelines, one above the other as the result of vertical movement. Agassizexplained them, rather, as successive shorelines of a glacial lake, now vanished because the retaining glacier has melted away. If so, and if global warming is real, we might expect to see vanishing lakes today, as the glaciers retreat. We can, and we do, as a recent blog post by my friend Peter Hess explains.

Glen Roy is a valley in the Western Scottish Highlands, just south of the Great Glen (home to Loch Ness), and draining through Glen Spean to Loch Linnhe, an inlet of the Atlantic. It is remarkable for the presence of the Roads, a series of parallel, almost horizontal, grooves in the hills on the sides of the glen. Clearly shorelines; but of what body of water? And why are there more than one of them?

From Darwin, C. R. 1839. Observations on the parallel roads of Glen Roy, and of other parts of Lochaber in Scotland, with an attempt to prove that they are of marine origin.  Philosophical Transactions of the Royal Society 129: 39-81, through Darwin Online

Charles Darwin visited the area in 1838, two years after his return from his round the world voyage on the Beagle. During that voyage, he had examined the geology as well as the plants and animals of the places he visited, and among them was the coastal area of Chile. This is marked by raised beaches inland where once had been shoreline, and Darwin correctly described these as the effects of uplift, which we now know to be driven by plate tectonics. So it was natural thatDarwin should have applied a similar explanation to the Roads, suggesting that the Cairngorms, like the Andes, were a zone of uplift, and that the Roads were ancient beaches of the Atlantic, now some ten miles away. The alternative theory, that they represented shorelines of an ancient lake, ran up against a seemingly conclusive objection; such a lake could only have formed if there had been a barrier across the valley, but there was no trace of this.Only a year later, shortly after going public with his Ice Age theory, the naturalist Louis Agassiz visited the area. In the Highlands he found plenty of evidence to support his idea; scratches on bedrock caused by the passage of glaciers, erratics (boulders far from their parent rock formations), and moraines (piles of rock rubble that had been carried by glaciers, left in place when the glacier melted). He considered the Roads further evidence of this; yes, there had been a lake, and yes, the roads did represent the shorelines at different times, carved into the sides of the valley by fierce freeze-thaw cycles. As for the barriers holding the lake in place at different levels over the course of time, they were a series of long vanished glaciers.

We now know that Agassiz was basically correct, although we now speak of a series of glaciations rather than a single Ice Age, and although Darwin was right in this; that the area has in addition experienced uplift, as the weight of ice above it has melted away.

Later Darwin was to write of this as his greatest blunder, describing in his Autobiography how in Wales he had missed the evidence of glaciation all around him, and generously acknowledging Agassiz for having come up with the correct explanation.

Agassiz rejected Darwin’s concept of evolution when it was published twenty years later because he believed in the fixity of species, but this does not seem to have diminished Darwin’s respect for him. What is now nothing but a deliberately cultivated ignorance was then, with so much less evidence available, no more than an understandable conservatism.

The overflow channel through which the vanished Loch Roy must have drained can still be detected as an abrupt narrow valley in the surrounding hillsides. The draining of the vanished lake in South America sent a surge through its own channel, down Chile’s main river, and caused giant waves as far as the Pacific Ocean, 60 miles away.

Lake to sandy valley overnight (from Peter Hess posting on NCSE blog site)

The glaciers of Switzerland are receding. Those of the southern Andes are receding even faster. Since Agassiz and Darwin examine the roads of Glen Roy, the earth’s mean surface temperature has increased by roughly 1oC, with another 0.5oC in the pipeline even if emissions were to be stabilised at the same levels as in the year 2000.

Which, of course, they won’t be.

Global warming: Yes it’s real and yes it’s CO2-driven; a former sceptic speaks his mind

Scientists are supposed to change their minds when the balance of evidence changes. In my experience, this doesn’t always happen, but one very respected scientist who has changed his mind, not once but twice, and very publicly, is Prof Richard Muller of the Berkeley Earth Land Temperature Project, UC Berkeley, and Lawrence Berkeley National Laboratory.

Three years ago, he was among the few remaining respected scientists to reject the IPCC (Intergovernmental Panel on Climate Change) analysis of current climate, and unconvinced that significant climate change was happening at all, let alone that it might be driven by human activity. Not surprising, then, that a consortium of those with an interest in denial funded his BEST (Berkeley Earth Surface Temperature) project, to carry out a completely independent, assumption-free, analysis of the data. They got more than they bargained for.

First, BEST concluded, in findings published last year, that warming is indeed taking place as asserted by the overwhelming majority of the climate science community. Now, even more significantly, BEST has taken the position, in a paper submitted to The Third Santa Fe Conference on Global and Regional Climate Change, that CO2 is the most significant driver, that the IPCC estimate of the effect of CO2 (3oC warming for each doubling of CO2 concentration) is accurate, and that the amount of warming from the 1950s to the 2000s (0.87 +/- 0.05 oC) is if anything slightly more than the IPCC estimate.

Moreover, the BEST publications analyse and dismantle all the standard objections to this work. Yes, there are effects due to volcanoes. I don’t think anyone denies this. The 1991 Mount Pinatubo eruption led to summers bad enough to force up the price of potatoes, but earlier events, such as the eruptions of Laki in 1783, Tambora in 1815, and Cosiguina in 1835, were much more significant. We know this from accounts at the time, and can quantitatively estimate the intensity of the eruptions by the amount of sulphate in ice cores. The late 18th and early 19th century data are good enough to provide a scaling factor (0.15 oC cooling per gigatonne emitted sulphate), showing that, by contrast, the overall effect of volcanoes in the 20th century has been insignificant. No, there is no significant effect attributable to the Sun. No, there are no artefacts due to the number and location of climate stations, although this has not stopped WattsUp, a Koch-funded enterprise, from raising this yet again in response to Muller. There is some variability connected with oscillations in the Atlantic, which may be responsible for the 0.17 oC variation from the simplest model. This model, which attributes all change to a linear volcanic effect, and a logarithmic CO2 effect, is remarkably successful. In the light of Muller’s work there is no excuse for invoking alleged scientific uncertainty to delay urgent consideration of the effects of further increasing CO2 concentrations, and the appropriate policy responses.

There are some particular words of caution. We don’t understand why the difference between day and night time temperatures decreased from 1900 to 1987, but then started rising again. We can’t be certain that present temperatures exceed those of the Mediaeval Warm Period, so beloved of climate “sceptics”, although it seems clear that if things continue as they are, the issue will be beyond all doubt. Warming has not led to more hurricanes, and the heat wave afflicting the United States this summer is local rather than global.

Muller’s approach includes the effects to date of one important feedback, the positive feedback due to the fact that ocean warming leads to increased concentrations of water vapour, the most significant of all greenhouse gases. However, of necessity, it neglects effects that have not yet kicked in, most of which can only add to our concerns. A tiny minority of climate scientists still maintain that increased cloud cover will moderate the effects of warming, but the evidence (see Science 2009, 325, 376, for a discussion) now shows that the opposite is true. Melting of sea and land ice will speed up warming, by reducing the Earth’s albedo, the fraction of incident sunlight that is reflected straight back into space, since exposed ground, crops, and open ocean absorb more energy and snow and ice. There is the prospect of release of methane from thawing tundra, and increased release of carbon dioxide from soils, as bacterial activity increases with warming. The only negative feedback in prospect is the greater reflectivity of deserts, as compared with cultivated land, but that is the last thing we should be looking forward to.

Thus Muller’s approach offers us the lowest credible estimate of what is in store for us. Despite which, opposition parties in Australia and the US, including one US presidential candidate, and a vocal faction within the United Kingdom’s governing Conservative Party, continue, and may be expected to indefinitely continue, in their denial that any real problem has been shown to exist.

I find this frightening.

This post is also available at

Denialgate; oil barons caught funding classroom anti-science

Denialgate is the name being given to the leaking of a parcel of documents from the Heartland Institute. This is a thinktank lying far to the right, even by American standards, and funded largely by an extremely wealthy “anonymous donor”, and by the Koch Brothers, oil barons, Tea Party funders, and each of them billionaires 25 times over. As I wrote in 21st Floor,  “ Koch Brothers, US oil billionaires who have spent millions promoting climate change denial (you didn’t think all those well produced “sceptical” or “real science” sites with nice sciency names just happened, did you?)” That may have been the first time that many people have heard of the Koch Brothers, but I fear that it won’t be the last, especially as US Supreme Court recently ruled that privately funded groups can spend unlimited amounts on political campaigns, and they are reported to be spending $60 million to defeat Obama (sound business; much cheaper than losing their tax breaks).

The Heartland Institute has many interests. One of their programs is called “health choice”, and their donors include Altria (that’s Philip Morris, the tobacco people). They fund Fred Singer, famous at one time for advising the tobacco companies on how to cast doubt of the link between cigarette smoke and health problems, but now apparently concentrating on climate questions. Regarding climate, the Institute has a long record of cherry picking and distortion, to create the illusion that the science of anthropogenic climate change is seriously in doubt. The strategy is to urge delay on grounds of uncertainty; to keep on claiming that the science is complicated (true) and controversial (true at one time, but no longer), and hence to infer that it is unwise to sacrifice immediate economic benefits to meet hypothetical future threats (non sequitur; as Margaret Thatcher pointed out 20 years ago, prudence implies the exact opposite). The tactics are to claim that anthropogenic global warming is a giant hoax by self-seeking scientists, and as evidence to present outlying points from the large but noisy available data set as typical. The sort of thing I discussed, in connection with how the Daily Mail (and in the US, Murdoch’s Wall Street Journal) have misrepresented the recent climate record. Denialgate now completes the military metaphor by showing us the Heartland Institute’s logistics.

There are six documents. One, a strategy outline, is quite different in style and tone from the others, and is the only one to have been explicitly denounced as a hoax by the Institute, while according to one of the Institute’s pet “experts”, Anthony Watts of the very professional Wattsup denialist website, PDF metadata confirmed its separate origin. Watts himself is a former TV weatherman, not a climate scientist. But then, climate scientists who deny the reality of anthropogenic global warming are about as common as life scientists who deny the reality of evolution.

The unintended consequence of these denials was to strengthen confidence in the authenticity of the remaining documents, including, crucially, the fundraising plan and budget. Finally, the distinguished environmental scientist Peter Gleick (MacArthur Foundation Fellow, member of the National Academy of Sciences) admitted that he had received the strategy document through the post from an anonymous source, and was then able to obtain the others directly from the Heartland Institute by a simple subterfuge. Heartland is frothing at the mouth over this piece of dishonesty; naturally, I have to join in this condemnation (ROFLMAO).

So what have we learnt? This, among other things:

The Heartland Institute is funded by Altria (better known as Philip Morris, the tobacco people) and by the Koch Brothers, whom we have already met, but most of its money comes from an anonymous donor.

The Institute plans to spend $249,000 on what it calls “Government Relations”.

The Institute is paying $5000 a month plus $1000 expenses to Fred Singer, a physicist who in the past advised the tobacco companies on how to cast doubt on the relationship between smoking and lung cancer, but is now better known for advising fuel companies on how to cast doubt on the relationship between carbon dioxide and global warming. (When questioned about this, Singer admitted to getting money from Heartland, evaded questions on the amount, and claimed to spend it all on student assistance.)

The Institute is also paying $88,000 to Anthony Watts, whom we have already met, for a new Internet venture. His present venture, Wattsup, will no doubt continue. Its main achievement was to perpetuate the myth that global warming was the result of an urban heat island effect, a case that he continues to argue even though, as I reported last week, an in-depth study funded by the Koch Brothers themselves found that this is simply not true.

Most ominously, the Institute is paying $100,000 to one David Wojick to prepare a series of 20 modules for classroom use on the subject of climate change. When challenged by a reporter, Dr Wojick emailed, with no sense of irony, “This means teaching both sides of the science, more science, not less.” (Where have we heard that before?) Dr Wojick really is an expert, but not on education, nor on climate science, but on data manipulation, and we can guess in what ways he will manipulate the data.

Meantime, climate change is increasingly finding its way into the “teach the controversy”, “sound science”, and “academic freedom” measures being introduced into US state legislatures, in parallel with Intelligent Design/Creationism. And while the creationist lobby relies on the generosity of the faithful, the climate change denialists are backed by some of the world’s deepest corporate purses.

[A version of this post has appeared on the 21st Floor site,  and forms part of the content of my article on recent developments in climate change studies in the first 2012 number of The Beacon, the house journal of  the New Mexico Coalition for Excellence in Science and Math Education]

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