Friday, January 14, 2011

Leading article: What the weather is telling us

Friday, 14 January 2011

The massive floods in Australia have tended to overshadow similar disasters in Sri Lanka, where a million people have seen their homes engulfed, and in Brazil, where 350 people have been killed and thousands affected by torrential downpours which are the worst in 25 years. The discrepancy might tell us something about the biases of western news media. But the phenomenon reveals more than that.

The wind and water movement known as La Niña is probably the immediate cause of the floods from Queensland through the Philippines to Sri Lanka as cold water from the coast of South America surges across the Pacific interacting with the normal north-east monsoon. Yet that may not be the only common factor. 2010 was a particularly extreme year, with record-breaking snowstorms in Europe and the United States, an unprecedented heatwave in Russia and floods across the globe from Pakistan to Tennessee. This week in Sri Lanka the temperature dropped to it lowest for 61 years.

Our perceptions of the weather are notoriously skewed by personal experience. December, despite the prodigious snowfall in the UK, was one of the driest on record; so much so that a hosepipe ban looms for next year already. Weather is not the same as climate. But two leading US monitors of global weather have revealed that 2010 was the hottest and wettest yet recorded. And it was the 34th year running that global temperatures have been above the 20th-century average. We have not had a below-average year since 1976. Nine of the 10 warmest years on record have occurred since 2001. The warmer it gets, the more unpredictable the weather will be.

It is beyond dispute that the Earth has been warming for decades. The vast majority of climatologists believe that is because we are releasing gases which trap heat inside our atmosphere. The level of carbon dioxide we produce has almost doubled since the Industrial Revolution. The link between that and climate change has not been definitively proved to be causal, sceptics constantly repeat. The problem is that by the time the proof is definitive, it will be too late to do much about it.

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