Scientific and Technological Issues Has the intensity of tropical cyclones increased due to global warming?ScientificRecords of hurricane activity can be judged by two factors-maximum wind speed -duration of hurricanes. The energy released by the average hurricane seems to have increased by around 70% in the past 30 years-corresponding to about a 15% increase in the maximum wind speed and a 60% increase in storm lifetime.TechnologicalReliable records of wind speeds in hurricanes go back only to around 1950, when aircraft reconnaissance of hurricanes beganSince about 1980, there are wind estimates for all hurricanes globally, based on satellite images,% but these are not as good as aircraft measurements.However, means of estimating the central surface pressure in hurricanes have remainedfairly constant with time. In practice, central pressure is well correlated with maximum wind speed How can we assert upswing in last 50 is caused by global warming?Can not say for sure, but can say that the change in hurricane energy consumption follows very closely the change in tropical sea surface temperature.-temperature falls, the energy consumption falls, -temperature rises, the energy consumption risesThe record of tropical ocean temperature is less prone to error and goes back 150 years or so.Geochemical methods have been developed to infer sea surface temperature from corals and from the shells.Can be used to estimate sea surface temperature for the past several thousand years. Records strongly suggest that the 0.5 degree centigrade (1 degree Fahrenheit) warming of the tropical oceans we have seen in the past 50 years is unprecedented forperhaps as long as a few thousand years. Scientists who work on these records therefore believe that the recent increase is
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