24 July 2007

Climate change and the British floods

The big news of the week in climate change is the publication of a paper in Nature by X. Zhang et al. which detects an anthropogenic effect on average precipitation amounts in latitudinal bands around the globe. From the abstract:

...that these changes cannot be explained by internal climate variability or natural forcing. We estimate that anthropogenic forcing contributed significantly to observed increases in precipitation in the Northern Hemisphere mid-latitudes, drying in the Northern Hemisphere subtropics and tropics, and moistening in the Southern Hemisphere subtropics and deep tropics. The observed changes, which are larger than estimated from model simulations, may have already had significant effects on ecosystems, agriculture and human health...

The Independent and other newspapers are already making the link with the record rainfall and floods in Britain.

Flood-ravaged Britain is suffering from a wholly new type of civil emergency, it is clear today: a disaster caused by 21st-century weather.

This weather is different from anything that has gone before. The floods it has caused, which have left more than a third of a million people without drinking water, nearly 50,000 people without power, thousands more people homeless and caused more than £2bn worth of damage - and are still not over - have no precedent in modern British history.

Nothing in the past hundred years, in terms of flooding caused by rainfall, has been as bad. According to the Environment Agency, even the previous worst case, the extensive floods of spring 1947, which were aggravated by the vast snow melt that followed an exceptionally hard winter, has been surpassed.

"We have not seen flooding of this magnitude before," said the agency yesterday. "The benchmark was 1947, and this has already exceeded it." And the 1947 floods were said to have been the worst for 200 years.

I suspect that the coincidence of the publication of this paper and the flooding events will leave an indelible imprints of the British people. If this does not serve as a wake-up call for the reality of climate change for them and rest of the world, it is unlikely that anything will.

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