World is warming after all

Tom Clarke

The world is warming and the much-criticised methods used by climate scientists to prove it are sound. That’s the conclusion of the largest independent review of global temperature records commenced in response to the 'climate-gate' emails scandal last year.

The review, conducted by physicists at the Berkeley Earth project drew together more than billion temperature records from 15 sources around the world dating from 1800 to 2009. They conclude that the earth’s land surface has warmed by about one degree centigrade on average since the 1950s.

Their conclusions closely mirror those of other teams of climate scientists, including Phil Jones at the University of East Anglia – the researcher at the centre of the hacked emails scandal.

Climate sceptics attacked the data those researchers used as being fundamentally flawed due to a phenomenon called the "urban heat island effect".

They argued that weather monitoring stations - from which the data is sourced – had been encroached upon over time by expanding cities. Because cities are, on average, about a degree or more warmer than surrounding countryside, critics argued that the temperature data was therefore biased towards a warming world.

Evidence of a warming trend

The re-analysis found that while individual stations could give spurious or incorrect readings, taken as a whole, they showed a clear warming trend.

"Our biggest surprise was that the new results agreed so closely with the warming values published previously by other teams in the US and the UK," said Professor Richard Muller, a physicist at the University of Berkeley in California, who led the study. "This confirms that these studies were done carefully and that potential biases identified by climate change sceptics did not seriously affect their conclusions."

Our biggest surprise was that the new results agreed so closely with the warming values published previously by other teams in the US and the UK. Professor Richard Muller

Accusations that the Berkeley analysis is biased will be hard for critics to support. The data they amassed is all being made available online. So too is the code for the software they designed to crunch the numbers. Moreover, the research was part-funded by oil billionaire Charles Koch whose organisation has been criticised by environmentalists for “climate denial.”

Leading climate skeptic blogger Anthony Watts, has already criticised the analysis as having a “basic procedural error” that he will argue should be corrected before the data is published in a peer-reviewed journal.

Other climate sceptics argue the Berkeley analysis is perfectly valid and that the media has misunderstood their critcisms of climate science. Their quibble, writes David Whitehouse of the Global Warming Policy Foundation, is not that the world is warming, but why.

"Sceptics who doubt that the earth is warming are few in number, and there is a widespread and respectable group of scientists who, in peer-reviewed journals, debate the relative mix of influencing factors concerning that warming."

The results of the Berkeley Earth Surface Temperature Study have been submitted as four separate scientific papers to the American science journal: Geological Research Letters.
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