Cold, hard facts take the heat out of some hot claims
Imagine if the American government agency responsible for temperature records had announced a fortnight ago that it had overestimated annual temperatures since the year 2000. Imagine if, at the time of correcting this error, the hottest year on record was mysteriously altered from 1998 to 1934. Imagine further that if you considered the 10 hottest years on record after these corrections, the hottest decade changed from the 1990s to the 1930s.
Would that change your views on global warming? It should, because climate change theory says increased carbon dioxide in the atmosphere raises the temperature. Yet the hot 1930s was hardly a decade of carbon-spewing industrial growth.
Well, all these things have happened. NASA's Goddard Institute for Space Studies calculates the average US temperature figures. It does this by processing data from land measurement sites. Earlier this year a Canadian mathematician named Steve McIntyre approached the institute and pointed out an error in its more recent calculations. Figures since 2000 had been inflated by about 0.15 of a degree celsius.
The institute thanked him and on August 7 quietly changed these figures, and some of the rankings on its list of the hottest years on record, which extends back to 1880. It did this without any public acknowledgment of the changes.
The Goddard Institute is a major supporter of the climate change orthodoxy, and the discovery that it got one of the central data sets of global warming science and debate wrong is embarrassing and disturbing.
Previously, McIntyre, along with the economist Ross McKitrick, had demolished the so-called "hockey stick" chart used in the third report of the Intergovernmental Panel on Climate Change. The graph incorrectly portrayed the history of the Earth's average temperature over the past millennium as essentially unchanged until a steep climb in the 20th century. This made a modest rise in temperature appear far more unusual than it really was.
The two men had difficulty gaining access to the data and methodologies used in creating the hockey stick, a difficulty facing many who want to question the most basic research on which the science of climate change rests. It was McIntyre's continuing interest in such basic questions, pursued publicly at his blog climateaudit.org, that led him to look at the problematic siting of many US land weather stations (see photos of them at the website SurfaceStations.org) and how the data they produce is processed.
Strange as it might seem in a scientific field that spends some $6.4 billion a year on often abstruse research and computer modelling, the integrity of the basic temperature data is emerging as a serious problem. The Goddard Institute claims to correct data from poorly sited stations, but McIntyre says it refused to tell him how it does this in sufficient detail for him to check its results. When he obtained some of the raw data from specific sites and compared it with the processed temperatures created by the institute, he found problems. In one case data from a good site, at the Grand Canyon, had been changed to make the 1930s colder than they were.
Across the Atlantic, the British mathematician Douglas Keenan has claimed that two important academic papers on the reliability of Chinese weather stations are wrong. This is a major issue because one of the papers is cited by the IPCC to support its position that measurement errors owing to urbanisation and the "heat island effect" - which makes cities warmer than their surroundings - are insignificant. Keenan claims to have discovered that some of the Chinese stations have been moved a lot. One, for example, had five different locations from 1954 to 1983, over a distance of 41 kilometres. This makes the data largely useless.
It took several years to gain access to the information needed to reveal this fault with the papers, because the academics involved refused to release it. Keenan finally obtained it by the creative means of using Britain's Freedom of Information Act, on the grounds that an academic who had the information was a public servant.
The climate change establishment is represented by the website realclimate.org. Its response to McIntyre's success in getting the Goddard Institute to reduce US temperature figures for the period since 2000 has been to say that the implication for global averages is imperceptible, since the US is only a very small fraction of the global area. Strictly speaking this is correct, although America's figures are more important than its land area might indicate because they go back so far in an unbroken line, which is fairly unusual.
Since the break-up of the USSR, the number of weather stations in the world has declined by half. Many of them used to be in cold areas. The scientists who compile global averages presumably try to take this into account - although in light of some of the above stories you have to wonder just how well they succeed.
Whatever the scientific implications of McIntyre's revelation, the rhetorical one is huge. America is the centre of the global debate on climate change. No longer will Americans or anyone else be able to say the hottest year on record in their great nation was 1998. Looking at the new top 10, it's hard to see any signs of global warming. The ranking, starting from the hottest year, goes: 1934, 1998, 1921, 2006, 1931, 1999, 1953, 1990, 1938, 1939.
It's a sad thought, but maybe we and our weather are not as unusual as some want to believe.