New Developments on Tropical Cyclones and Climate Change

One of the goals of the Cyclone Center project is provide a more definitive answer on how tropical cyclones (TCs) have been responding to the dramatic changes that our climate is undergoing.  It is difficult for meteorologists to determine how strong tropical cyclones are getting because we rarely observe them directly, relying primarily on satellite data to give us a decent estimate of the wind speeds.  But as you can imagine, it is very hard to determine the maximum winds in a hurricane when you are in the hurricane itself, let alone flying more than 22,000 miles above it!  Our record of tropical cyclones is by no means nailed down.

http://www.epa.gov/climatechange/images/indicator_figures/sea-surface-temp-figure1-2012.gif

Ocean temperatures have been warming, which provides more energy for tropical cyclones (Image from the EPA)

So people have some differences of opinion on what has been going on in recent years.  Perhaps even more interesting is what will happen in the future.  There are theories that predict the characteristics of tropical cyclones in future years as the rate of ocean and atmospheric warming accelerate.  Most scientists believe cyclones will be more intense as global oceans warm.  There are reasonable disagreements on the number of tropical cyclones forming, since the formation of TCs are sensitive to other things like winds and moisture in the atmosphere.

In the Atlantic Ocean, which of course is of the most interest to the United States and Caribbean nations, the traditional view is that storms will be stronger but less frequent.  A recent study by Kerry Emanuel, a well-respected tropical meteorologist, suggests that we may not be so lucky.  Using the latest high-resolution computer models that simulate TC-like circulations, his results show a 40% increase globally in the strongest TCs (Category-3 or higherand an increase in numbers of TCs in several basins including the North Atlantic.  One has to always be cautious of computer model projections, and it remains to be seen if further evidence comes out to support Emanuel’s conclusions.  But we can accept without doubt that the threat of TCs will remain.

The work of citizen scientists like you on Cyclone Center is already producing results that will help rectify differences in the historical TC record.  As for the future, we’ll just have to wait a little bit on that.

– Chris Hennon is part of the Cyclone Center Science Team and Associate Professor of Atmospheric Sciences at the University of North Carolina at Asheville

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