Climate change and Hurricane Katrina

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Meteorologists and Oceanographers are not crediting "climate change" or "global warming" as a direct cause of Hurricane Katrina, but there is an increasingly clear connection between global warming and increased storm strength.

It is well known that hurricane strength is directly proportional to the heat content of the waters which feed the storm; but there are plenty of sources for that heat. And of course, hurricanes are much more complicated than just that one element.

Two recent articles, one in the August issue of Nature, and one in the most recent (September, 2005) Science Magazine, have introduced dramatic new evidence that global warming has significantly affected hurricane destructiveness. These findings are further supported by an earlier article in Science Magazine (8 July 2005) reporting clear evidence of human-caused global warming in the Earth's oceans. The article in Nature shows a strong correlation between sea temperature and annual hurricane power in three different hurricane basins, the North Atlantic and two in the Pacific.

The measured temperature changes are mainly not due to global warming, and that is the strength of this research. While the National Hurricane Center claims the increase in hurricane destructiveness since 1995 is due to “Atlantic Ocean fluctuations” it does not say what was fluctuating. This research shows it was mainly temperature, hence ocean warming is causing what is acknowledge to be a dramatic increase in hurricane destructiveness. The question then becomes, what caused the ocean warming. All experts acknowledge that, to a significant extent it is caused by a “multi-decade” natural cycle. But this cycle alters the ocean temperature only about 1 degree F, which is about the same amount that global warming is estimated to have increased ocean temperature. The conclusion is then inescapable: if anthropogenic ocean warming has occurred as estimated, it must have dramatically affected hurricane intensity.

The most recent Science article studies the percent of category 4 and 5 hurricanes in six hurricane basins world wide and finds that it has increased significantly in the last 30 years in each basin. reviews both articles and pushes their analysis a bit further with better statistics and more recent data.

The abstract of the earlier Science article, "Penetration of Human-Induced Warming into the World's Oceans," stated, in part: "A warming signal has penetrated into the world's oceans over the past 40 years. The signal is complex, with a vertical structure that varies widely by ocean; it cannot be explained by natural internal climate variability or solar and volcanic forcing, but is well simulated by two anthropogenically forced climate models. We conclude that it is of human origin, a conclusion robust to observational sampling and model differences."

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