Saturday, September 22, 2007

Climate change: a picture is worth a thousand words


(Picture stolen from the Daily Telegraph. The top shows the extent of Arctic sea ice in September 2005, the bottom in September 2007)

In 2005, the arctic ice-cap shrank to its smallest extent in recorded history. This year, it's smashed that record, shrinking to a mere 4.13 million square kilometres, compared with the previous low of 5.32 million square kilometres. Previously, climate scientists had been estimating that if climate change continued the arctic would be ice-free around 2080. Now they're talking 2030. This isn't about our children anymore - it will happen in our lifetime.

Worse, the disappearance of the arctic ice-cap will have a significant positive feedback effect on climate change. Ice has a high albedo - it reflects incoming sunlight - so the icecap helps keep the planet cool. Water, OTOH, is darker, and absorbs sunlight. So the result will be more heat pumped into the system, and a dramatic quickening of the warming trend.

The need for swift action is now undeniable (though I'm sure the US-backed Denial industry will find some way to do so. The polar icecap is being stolen by Islamic terrorists?). Given the projected timescale, we are now almost certainly committed to seeing the Arctic melt, with a consequent flow-on effect for the rest of the global climate. But we can reduce the severity of that further impact through significant emissions cuts now. And its up to our governments to do so.