‘It’s fact, not theory: extreme weather due to global warming’

Published on 06/08/2012 01:47

A LEADING Nasa scientist has claimed the current period of unpredictable weather cannot be attributed to anything other than man-made global ­warming.

Dr James Hansen, who was awarded the prestigious Edinburgh medal this year at the city’s Science Festival, said recent trends in global weather can no longer be put down to random occurances.

Dr Hansen, a scientist at Nasa’s Goddard Institute for Space Studies in New York, said: “The increase in the chance of extreme heat, drought and heavy downpours in certain regions is so huge that scientists should stop hemming and hawing.

“This is happening often enough, over a big enough area that people can see it ­happening.

“The likelihood of such temperatures occurring from the 1950s through the 1980s was rarer than one in 300.

“Now, the odds are closer to one in 10. Statistically what’s happening is not random or normal, but pure and simple climate change.”

Dr Hansen’s research uses simple maths rather than complex climate models to highlight his view that the current weather – including blistering heat in some areas and almost relentless downpours in others – is purely a result of climate change.

He said: “This is not some scientific theory. We are now experiencing scientific fact.”

Part of his latest study blames three heat waves purely on global warming – the 2011 Texas-Oklahoma drought, the 2010 heat waves in Russia and the Middle East and the European heat wave in 2003.

Dr Hansen, often referred to as the “godfather of global warming”, hopes his new study will shift people’s thinking about climate change and goad governments into action to curb greenhouse gas emissions.

Writing online in the Proceedings of the National Academy of Science, he said: “There is still time to act and avoid a worsening climate, but we are wasting precious time.”

Andrew Weaver, a climate scientist at Canada’s University of Victoria, praised the study saying it “reframes the question” on global warming by highlighting how radical changes in weather which are happening worldwide have to be as a result of climate change.

He said: “Rather than say, ‘Is this because of climate change?’ That’s the wrong question. What you can say is, ‘How likely is this to have occurred with the absence of global warming?’

“It’s so extraordinarily unlikely that it has to be due to global warming.”

But other experts say previous studies have been unable to link the extreme weather to climate change.

One, carried out by the National Oceanic and Atmospheric Administration, found no evidence the Russian drought which led to devastating wildfires was related to global ­warming.

Scientist John Christy, of the University of Alabama in the US, said the Nasa expert should not have compared recent years to the 1950s-1980s time period because he said that was “a quiet time for extremes”.

Derek Arndt, director of climate monitoring for the US government’s National Climatic Data Center, said the four decade period range was a fair one and often used because it was the “golden era” for good statistics.