Increase in Mediterranean TCs?

Beyond Katrina highlights an article on the possibility that climate change may bring more tropical cyclones to the Mediterranean region, linking to this story in the Times Online. The gist of the story:

“We have detected for the first time a risk of tropical cyclone development over the Mediterranean based on anthropogenic climate change,” said Miguel Gaertner, lead researcher at the environmental sciences faculty of the University of Castilla-La Mancha in Toledo, Spain.

The Times article also notes some recent occurrences of similar phenomena.

Recently, however, researchers found hurricanes forming where they had never been seen before. In 2004 Cyclone Catarina became one of the very few ever to form in the South Atlantic, hitting the coast of Brazil.

Then, in 2005 Hurricane Vince formed around Madeira, an area that had never before produced such storms. It even struck Spain – another first.

A quick search on Wikipedia suggests that while events like Catarina and Mediterranean TCs are rare. Looking at the times of occurrence noted in those articles, it would appear that they are becoming more frequent in recent years,consistent with the hypothesis of climate change. However, whether that is due to better observing and/or data in the modern era or an actual trend remains unclear at this time (and likely to remain so...).

There is also the issue of the categorization of these storms. Are they polar lows, subtropical cyclones or tropical cyclones? In some sense, it is really a matter of semantics. The fact is that unusual storms are occurring at unusual times and in unusual places. This is the issue.

The consequences may be relatively minor now, but they are potentially large in the future. A sensible risk management approach would be to act now to prevent catastrophe down the road.