More Flooding.

For more then three weeks Australia's North-eastern province of Queensland has been experiencing extreme flooding that has so far killed 12. For about the same length of time Sri Lanka has also been experiencing extreme flooding that has killed 23 and forced another 325,000 onto emergency food aid. In the last few days Brazil has joined this unfortunate group with flooding and mudslides that have killed at least 370 with the death toll expected to rise as high as 500.

Obviously now is not the time to be playing politics. However these extreme weather events and natural disasters do serve as further evidence of global warming and climate change. Over the years global warming has caused global ice masses to melt increasing the amount of water in the hydrosphere. In the northern hemisphere, which is currently experiencing it's winter, this extra water has frozen and fallen as snow. In the southern hemisphere, which is currently experiencing it's summer, this water has fallen as extra heavy monsoon rains. This trend of increased rainfall has actually been going on for a couple of years now but normally the trade winds cause the rain to fall over the vast expanse of the Pacific Ocean so no-one really noticed.

This year the La Nina weather system has changed all that. Normally what happens is you get two areas of high air pressure off the coasts of Australia and Peru creating an area of low pressure across the Pacific. This allows all the weather from Australia and the Indian ocean to sweep into the area of low pressure. Due to changes in ocean temperature La Nina forces the South-American area of high pressure back across the Pacific until it meets the Australian area of high pressure creating a blocking system. This quite literally blocks the rains from moving out across the Pacific and prevents weather systems formed in the Indian ocean moving on towards Australia. With an area of low pressure now formed over South-America weather systems that were formed over the Atlantic Ocean are able to force their way across the continent starting with Brazil.

Given the role that climate change has played in these floods it is perhaps a cruel irony that the extensive coal mining that goes on in Queensland actually makes Australia the worlds largest, per capita, emitter of greenhouse gases. For the last couple of years there have been heated political arguments in the country over whether or not a levy a sort of carbon tax against these mining operations. The flood water has shut the mines down completely.