Climate shift: powerful tropical cyclones reaching peak intensity farther from equator …

May 2014 – CLIMATE – According to a new study, powerful tropical cyclones are reaching peak intensity father from the equator and closer to the poles. Published today in the journal Nature, the study’s results show that over the past 30 years, tropical cyclones, or hurricanes and typhoons, are moving closer to the poles at a rate of about 33 miles per decade in the Northern Hemisphere and 38 miles per decade in the Southern Hemisphere. Kerry Emanuel, an MIT professor and co-author of the paper, says: “The absolute value of the latitudes at which these storms reach their maximum intensity seems to be increasing over time, in most places. The trend is statistically significant at a pretty high level.”  Emanuel says that trend seems consistent with a warming climate, adding that “it may mean the thermodynamically favorable conditions for these storms are migrating pole-ward.” The implications of these results are serious as the movement of peak intensity means regions further north and south of the equator, which before haven’t had to endure many landfalls by dangerous cyclones, may have greater exposure to these extreme weather events. This could lead to “potentially profound consequences to life and property” and “any related changes to positions where storms make landfall will have obvious effects on coastal residents and infrastructure.”

To conduct the study the researchers used international data from 1982 to 2012 that was collected by NOAA’s National Climactic Data Center and used the location of peak intensity of cyclones as a benchmark because it is a more consistent metric than statistics such as storm duration. There are regional differences in the pole-ward movement of cyclones, the fact that every ocean basin other than the northern Indian Ocean has experienced this change leads the researchers to suggest that this “migration away from the tropics is a global phenomenon.” Emanuel adds that the global mechanisms that underlie the trend are a matter for additional research. –Cleveland Leader