By Richard Black
Environment correspondent, BBC News website
Some claim science itself is weighted against sceptical views
Of all the accusations made by the vociferous community of climate sceptics, surely the most damaging is that science itself is biased against them.
That was a view I put forward nearly a year ago now in another article for the BBC News website, and nothing has changed my mind since.
The year seems to have brought no diminution of the accusations flying around the blogosphere.
"The research itself is biased," as one recent blog entry put it.
"Scientists are quick to find what they're looking for when it means getting more funding out of the government."
That particular posting gave no evidence to support its claim of bias. I have seen none that did, which made me wonder whether there was any evidence.
Drought or deluge?
In that earlier article, I invited sceptics to put their cards on the table, and send me documentation or other firm evidence of bias.
For my part, I agreed to look into any concrete claims.
Given the fury evidenced by sceptical commentators, I was expecting a deluge.
I anticipated drowning in a torrent of accusations of research grants turned down, membership of the Intergovernmental Panel on Climate Change (IPCC) denied, scientific papers refused by journals, job applications refused, and invitations to speak at conferences drying up.
I anticipated having to spend days, weeks, months even, sifting the wheat from the chaff, going backwards and forwards between journal editors, heads of department, conference organisers, funding bodies and the original plaintiffs.
I envisaged major headaches materialising as I tried to sort out the chains of events, attempting to decipher whether claims had any validity, or were just part of the normal rough and tumble of a scientist's life - especially in the context of scientific publishing, where the top journals only publish about 10% of the papers submitted to them.
The reality was rather different.
I received e-mails from well over 100 people; some had read my original article, others had seen the idea passed around in blogs and newsgroups.
Four people said they had had problems getting research published, and three sent me the papers in question.
The other said he did not want to disclose details as he was preparing his paper for submission to another journal.
Of the three papers I did receive, one was far from complete, and another was a review article from an author who endorsed the IPCC position and said the bias was against scientists "supporting man-made climate change".
Some proposed author Michael Crichton as the authority on bias
The third was from Reid Bryson, a US meteorologist and climatologist whose team at the University of Wisconsin has developed its own method of looking at historical climate change.
He said he had had problems getting research published on the extent to which he believes volcanoes drive climate change.
But he had not kept his rejection letters, so it was impossible to investigate specifically.
A fifth correspondent said magazines had turned down letters for publication; but letters are not research, and magazines are not journals, which perform a vital role in the formal processes of science.
In terms of first-hand claims of bias, that was it.
At second hand
Other correspondents referred to two well-known cases involving the top-line journals Science and Nature.
Nature's refusal to publish a re-analysis by Stephen McIntyre and Ross McKitrick of the famous (or infamous, depending on your point of view) "hockey stick" graph has been so well documented elsewhere, not least in hearings instigated by US congressmen, that there is really nothing new to say.
The Science issue involved its decision not to publish a response by UK academic Benny Peiser to a paper by Stanford University's Naomi Oreskes, in which she had claimed to find more or less unanimous support for man-made climate change among published scientific papers.
This saga has also been so well documented, not least on Dr Peiser's website, that again there is little new to say, except that Dr Peiser now says he is glad Science decided not to publish his research because "my critique of Oreskes' flawed study was later found to be partially flawed itself".
Another correspondent raised an apparently similar issue, where Japan-based researcher James Annan had repeatedly been rejected in his bid to publish a comment article on "climate sensitivity", a term widely used to mean the temperature rise seen in response to a doubling of atmospheric carbon dioxide.
It is a key figure, because it basically tells you how fast the Earth warms as CO2 levels rise.
Last year the journal Geophysical Research Letters (GRL) published a paper from Dr Annan's group using historical data to indicate a value probably between about 2C and 4C.
If this is correct, it rules out both the lower estimates of about 1C favoured by some climate sceptics, and the higher values of about 6C which some scientists believe could swiftly bring catastrophic impacts.
Later, the researchers wrote a comment piece emphasising that values above 4.5C were very unlikely. GRL and one other journal have collectively turned it down a total of five times.
"I think it does count as bias to some extent," Dr Annan told me.
"But it's not really a 'sceptical' or 'alarmist' bias; it's more a political thing to do with not wanting to offend the wrong people. It's a bit of gentlemen's club."
He also pointed out that while the emphasis of his comment piece was on ruling out high "catastrophist" scenarios, the data itself was the same as in his earlier paper, which had been published in a prestigious journal.
The rest of the emails contained a mixture of positive and negative comments on the worth of this exercise, links to newspaper articles and blog entries that typically contained accusations of bias but no evidence, links to scientific papers which the writers said challenged anthropogenic warming, tirades against the media, and several suggestions that for an authoritative exposition of bias in climate science I should read Michael Crichton's novel State of Fear.
Known and boring
Several people who wrote to me argued that my original definition of bias was insufficiently subtle.
"Scientific bias occurs the same way that any bias is created, when people say 'I have already figured this out, so I do not need to revisit it'," said Forrest Baker.
Others said that with billions of dollars spent each year on climate research, no-one would risk "rocking the boat" by performing, or publishing, work that could refute humankind's carbon emissions as the cause.
Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research in Germany, who is something of an anti-hero to sceptics' groups as he believes IPCC projections of sea-level rise are far too conservative, had heard this argument before, and he wrote in telling me it was far from convincing.
"How likely is it that my funding would suffer if I found a good alternative explanation for the observed global warming, or that I would have trouble publishing it (assuming it would be methodologically sound, of course)?" he asked.
"Quite the contrary, I would see it as a path to certain fame! Scientists always strive to find something radically new and different - just reconfirming what is already quite well-known is boring, and certainly will not get you the Nobel Prize.
"In many countries, including my own, scientific funding is a lot less competitive than in the US - I'm a professor for life, my institute has a solid base funding for doing its research, and basically I can do what I want without risk that this is taken away from me. I don't need to get new grants all the time."
And some research groups are investigating ideas which could challenge anthropogenic warming. For example, several teams have published work within the last three years on the Sun's possible role as a driver of modern-day warming.
One is Henrik Svensmark's group from the Danish National Space Center (DNSC), which published results of laboratory work in the journal Proceedings A of the Royal Society last year - work which they claimed showed the Sun, rather than greenhouse gases, as the chief actor.
"As editor, I can't have a position on publishing any scientific paper other than that it should be peer-reviewed," commented the journal's editor-in-chief Professor Sir Michael Berry when I asked him whether there was a climate bias in scientific publishing.
"I wouldn't pay any attention at all to whether it's 'sceptical' or not."
The sum total of evidence obtained through this open invitation, then, is one first-hand claim of bias in scientific journals, not backed up by documentary evidence; and three second-hand claims, two well-known and one that the scientist in question does not consider evidence of anti-sceptic feeling.
No-one said they had been refused a place on the IPCC, the central global body in climate change, or denied a job or turned down for promotion or sacked or refused access to a conference platform, or indeed anything else.
If there is an anti-sceptic bias running through the institutions of science, it is evidently keeping itself well hidden.
Whether this exercise has conclusively disproved a bias is not for me to say - I am sure others will find plenty to say, doubtless in the courteous and gracious language that typifies climate discourse nowadays.
But I will say this; if someone persistently claims to be a great football player, and yet fails to find the net when you put him in front of an open goal, you cannot do other than doubt his claim.
Andres Millan, who wrote to me on the subject from Mexico, offered another explanation for why scientific journals, research grants, conference agendas and the IPCC itself are dominated by research that backs or assumes the reality of modern-day greenhouse warming.
"Most global warming sceptics have no productive alternatives; they say it is a hoax, or that it will cause severe social problems, or that we should allocate resources elsewhere," he wrote.
"Scientifically, they have not put forward a compelling, rich, and variegated theory.
"And until that happens, to expect the government, or any source of scientific funding, to give as much money, attention, or room within academic journals to the alternatives, seems completely misguided."