The three devastating record-breaking hurricanes of recent weeks may only be a sample of things to come if climate change is unimpeded, an MIT scientist says.
Hurricane Harvey, which brought havoc to parts of the Texas coastline, produced more rainfall than any U.S. hurricane on record and is considered to be a one-in-2,000-years event. But given a changing climate, causing such storms to become much stronger and reach peak intensity further north, this probability could drop to one in 100 years. Hurricane Irma, with its record-breaking duration as a Category 5 storm, will go from being a one-in-800-years event in the area to a one-in-80-years event by the end of this century, says Kerry Emanuel, a professor of atmospheric science at MIT.
“Climate change, if unimpeded, will greatly increase the probability of extreme events,” he says.
Emanuel has long been considered one of the leading researchers on tropical storms, including hurricanes and cyclones. The MIT researcher recently gave a talk entitled “What do Hurricanes Harvey and Irma Portend?” looking at the recent string of hurricanes that have devastated the Caribbean and the U.S.
Over the last four decades, hurricanes and cyclones globally have caused an average of $700 billion in damages annually since 1971. At the same time, because of population growth and the development of oceanfront property, the global population exposed to hurricanes has tripled since this time.
Emanuel says that because of policies to federally provide flood insurance gives private insurers little motivation to study countermeasures, meaning hurricanes such as Harvey, Irma and Maria will be continuing to happen as more people get put in places where they are vulnerable to such devastating forces.
Predicting Storm Patterns
One difficulty in providing clear documentation on the increasing intensity of hurricanes is the sparsity of historical records. Prior to 1943, everything that is known about hurricanes is from anecdotal accounts including ships’ logs and news accounts from coastal cities.
Emanuel has devised ways of deducing the hurricane record over much longer periods using techniques such as taking cores from coastal lagoons to reveal periods when storm surges drove quantities of beach sand far inland and analyzing the annual rates of shipwrecks over a period of centuries.
At the same time, new technologies—such as a technique for deriving wind speed information from the radio signals from GPS navigational satellites—are starting to provide unprecedented degrees of detail of the internal dynamics of hurricanes. This may help researchers continue to refine models and allow for more accurate forecasting of hurricanes. However, while tracking hurricanes has improved, the ability to predict the strength of coming storms is not yet as good, MIT says
Emanuel says his calculations of the physics behind the formation and growth of hurricanes indicate that the strength of these storms will continue to increase as the climate warms but that there are inherent limits to the growth. At some point the maximum size of such storms will begin to level off but these limits are still a ways off. In the near term, U.S. rainfall events as intense as hurricane Harvey have an already increased likelihood of about 6 percent annually and by 2090 could be as much as 18 percent, this is way up from the likelihood of 1 percent in the 1990s.