Monday, October 16, 2006

Blowing in the wind

Last Thursday the temperature hit 43 degrees at Eyre on the Nullarbor Plain. It was a record for October out there. But there ain't no stats on humidity records. But the relative humidity that day was 1% in Eyre. In SE Australia, below 15% is considered to be extreme fire conditions. The air was dry and hot all the way up to Giles and Uluru that day, and that air is what fed the fires in Tasmania the next day. It surfed down ahead of the cold front coming across from south of W.A.

Now the reason the air was so dry and hot is a bit of a mystery but there is a clue in the ozone hole which is now affecting the position of the jet stream. The southern hemisphere jet stream that week was dipping and turning steeply south east across the centre of Australia. It was dumping air out of the stratosphere over the north west interior(south of Balgo). The ozone hole has stretched out over the antarctic like a dumbell and is beginning to rotate relative to the earth it's currently moving past South Africa . It was the secondary wave created from the hole deforming the jet stream that pushed it into an extreme meridional pattern.

It's what you get when you destroy the ozone layer and raise the level of CO2 at the same time - the start of a worrying synergy. The ozone hole is constrained not by the amount of chlorine in the stratosphere but by the temperature and area of the antarctic stratosphere. The chlorine only builds up in the winter dark which is set by the size of the earth and doesn't change. And the clouds of SO2 ice that catalyse the reaction only form when the temperature is cold enough. The problem is the stratosphere gets colder as the lower atmosphere gets warmer. As well, the CFC's and the other halo-carbon gases all contribute an order of magnitude more of warming than CO2(weight for wieght), in the troposphere as well.

We get it both ways.

I've been listening to some rather eminent people propound a sceptical viewpoint about climate change recently and I must say that some of them should consider their positions carefully. The president of the Victorian Farmers Federation is itching to start a class action for damages because of climate change. He's not the only one I'm sure. People in prominent positions have a duty to not ignore the evidence just as they have a duty not to ignore a crime. The current political climate might protect them but the winds of change are blowing hard today.

Mind you, I suspect that the drought will break this summer over eastern australia and the ozone hole is showing some positive signs of repairing itself quicker this year than previously.

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