STATISTICAL EVIDENCE LINKS EXCEPTIONAL 1995 ATLANTIC HURRICANE SEASONTO RECORD SEA WARMING

Tropical cyclones rank above earthquakes as the major geophysical caus e of loss of life and property (Bryant, 1991; Houghton, 1994). In the United States alone, the damage bill from mainland landfalling hurrica nes over the last 50 years averages $2.0 billion per year (Hebert et a l., 1996). Years with high numbers of hurricanes provide new insight o n the environmental factors influencing interannual variability; hence the interest in the exceptional 1995 Atlantic season which saw 11 hur ricanes and a total of 19 tropical storms, double the 50-year average. While most environmental factors in 1995 were favourable for tropical cyclone development, we show that a factor not fully explored before, the sea surface temperature (SST) was the most significant. For the 1 0 degrees-20 degrees N, 20 degrees-60 degrees W region where 93% of th e anomalous 1995 hurricanes developed, similar to 45 year statistical regressions show that SST is the dominating influence, independent of all known other factors, behind the interannual variance in Atlantic h urricance numbers. With this SST experiencing record warm levels in 19 95, 0.66 degrees C above the 1946-1995 mean, these regressions indicat e that sea warming explains 61+/-34% of the anomalous hurricane activi ty in 1995 to 95% confidence.