Thursday, January 22, 2009

Climate change: another denier myth debunked

West-Antarctic-in-red-has-002

(Image stolen from the Guardian)

As the evidence for anthropogenic global warming has steadily increased, climate change deniers have clung increasingly to a single claim; Antarctica is cooling, therefore the scientists must all be wrong, and we can continue to burn coal and pollute the atmosphere with wild abandon.

That myth has now been well and truly busted. A study published in Nature this week has combined satellite and ground station data to show a warming trend across the entire continent over the last 50 years, which has been partly offset in East Antarctica by the (now shrinking) ozone hole:

Temperature records have been taken on the ground since the first weather stations were built in 1957. But all but two of the 42 are very close to the coast and therefore give no information on the vast interior of the continent. Satellite data, in contrast, can take the temperature of the entire region by measuring the intensity of the infrared radiation reflected from the snow pack and has been available since 1980.

Steig's team found the mathematical relationships between the weather station data and satellite data, tested them, and then used them to go back in time to estimate temperatures across the continent back to 1957. Their statistical model has now been validated by an ice core drilled into the Rutford ice stream in West Antarctica by the British Antarctic Survey, from which temperature records can be measured. That independent work also came up with a warming of 0.17C a decade for the region, and stretched the trend back to at least 1930.

According to the full article, the effect is "difficult to explain" without the effect of rising greenhouse gas concentrations.

So much for the myth of Antarctic cooling. Unfortunately, this is unlikely to stop the deniers from appealing to it. Like sunspots, "the world is cooling", and a host of other nutty theories disproved by the empirical evidence, it will simply hang around as a "zombie fact", regardless of its falsity. Which begs the question: if they're just not interested in the empirical evidence, why does anyone even pretend to pay attention to them?