Friday, 23 January 2009

And one for the sceptics from the Independent of 23 January 2009

The cable news network CNN has sacked its science team, and one of the consequences has been a number of embarrassing programmes about how the exceptionally cold weather in North America this winter contradicts global warming and supports the idea that we are actually due for or a period of global cooling, if not a full-blown ice age.

"And tonight, last year, one of the coldest years in American history. Is it evidence that global warming is being overstated? Or are we headed toward a new ice age? Or none of the above. We'll be joined by three of the world's leading authorities on climate change and physics," said CNN anchorman Lou Dobbs before being joined by some of the best-known climate sceptics in American history.

There is of course a heap of difference between weather and climate, and no scientist worth his or her research grant would dare to suggest that any one bout of extreme weather is the result of climate change, unless it was so extreme and prolonged that it bounces out of the statistical ballpark of natural variability – which is what happened with the hot summer of 2003 in France and Italy.

But a recurring theme among climate sceptics is that there is a genuine division of opinion among mainstream scientists over the reality or otherwise of climate change. Anyone listening to Radio 3's otherwise erudite Nightwaves last Tuesday night, for instance, would have heard a scholarly voice stating that scientists disagree over climate change, with some believing we are about to enter another ice age.

Well it depends what you mean by "about to". In another 10,000 years or so, another ice age may be upon us, as a result of longer-term cycles such as the way the Earth tilts, rather than atmospheric changes. But in the meantime we will have to cope with a predicted rise of between 2C and 6C by 2100 – the same sort of temperature difference between now and the last ice age. We are indeed heading for another ice age, but the question is whether we can survive an intervening period of possibly intense global warming.

Suggesting that there is a division of opinion among experts is a tried-and-trusted method of questioning the orthodoxy. It was done for the discredited idea that HIV doe not cause Aids, and has been practised by creationists to undermine Darwinist evolution.

For the record, there is little division among experts over global warming. Peter Doran of the University of Illinois in Chicago has published a study in Eos showing that 97 per cent of scientists engaged in climate research believe human activity has played a role in the increase in average global temperatures over the past 200 years. That's a pretty convincing consensus.

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