Hurricane patterns are natural

The Times reports on a new Swedish study:

Hurricanes in the Atlantic are increasing because of natural weather patterns rather than global warming, a study has concluded.

Growing numbers of hurricanes battering the United States and the Caribbean have made their presence felt in the past decade and are forecast to worsen. Global warming has been cited as a possible cause but researchers looking at sediment and coral deposits have now identified natural variations in their frequency.

Hurricane Katrina, which devastated New Orleans in 2005, was “unexceptional” when historic patterns of such stormy weather are analysed, they suggested.

Global warming may even have been responsible for unusually low levels of hurricanes in the 25 years before 1995 when the number began rising, according to the scientists, led by the Geological Survey of Sweden…

“The record indicates that the average frequency of major hurricanes decreased gradually from the 1760s until the early 1960s, reaching anomalously low values during the 1970s and 1980s,” they reported in the journal Nature. “Furthermore, the phase of enhanced hurricane activity since 1995 is not unusual compared to other periods of high hurricane activity and appears to represent a recovery to normal hurricane activity.”

The findings are at variance with the conclusions in February of the Intergovernmental Panel on Climate Change, the United Nations organisation addressing global warming. The UN panel stopped short of blaming increased frequency of hurricanes on man-made temperature rises, but said it was “more likely than not” that greenhouse gas emissions had contributed to the greater intensity of cyclonic storms.