Mississippi River
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Global Warming
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Global Warming: Effect on Hurricanes
Written by YeSeul Kim, Erika Granger, Katie Puckett, Cankutan Hasar, and Leif Francel


Effects of Global Warming

Hurricanes are affected by a wide range of factors, however the two most important factors in determining the potential intensity of a hurricane are sea surface temperature (SST) and the temperature at the storm top.  The equation for maximum wind velocity is as follows (Emanuel, 1999):


Graph 2: The part of the equation that is circled in red is the part that we are concerned about.  It means that climate temperature affects potential hurricane intensity through the difference between absolute SST and absolute temperature at the storm top (upper troposphere to lower stratosphere) divided by the latter.  Therefore if climate change causes SST to rise faster than atmospheric temperature, potential wind velocities should increase, and, therefore, potential hurricane intensity should increase as well.  This discrepancy between the rate of change of SST and the rate of change of atmospheric temperature (in the vicinity of the height of the storm top) has been observed in a careful analysis by Kerry Emanuel.  This is corroborated by the Board of Atmospheric Sciences and Climate (2000). As hurricanes reach higher intensities, the time it takes for them to build up to those higher intensities and then to dissipate will have increased from that of lower intensity hurricanes (Emmanuel, 2005).


Whether or not a changing climate is affecting or will affect the frequency of hurricanes is extremely controversial at the moment.  While it is important to know whether the frequency of hurricanes will increase or not (the more hurricanes there are, the more there are that could potentially make landfall), there isn’t enough data available to predict whether or not there is a trend in hurricane frequency.  Even if there is a trend, there is not enough data to link it (or not link it) to global warming (Trenberth, 2005).