Twice as many Atlantic hurricanes formed each year from 1995 to 2005, on average, than formed during parallel years a century ago finds a new statistical analysis of hurricanes and tropical storms in the north Atlantic. The researchers conclude that warmer sea surface temperatures and altered wind patterns associated with global climate change are responsible for the increase.
The study, by Greg Holland of the National Center for Atmospheric Research, NCAR, and Peter Webster of Georgia Institute of Technology, is published online today by the Royal Society of London.
For the 2007 Atlantic hurricane season, NOAA scientists predict 13 to 17 named storms, with seven to 10 becoming hurricanes, of which three to five could become major hurricanes of Category 3 strength or higher. An average Atlantic hurricane season brings 11 named storms, with six becoming hurricanes, including two major hurricanes.
The changes in sea surface temperatures took place in the years before to the sharp increases in storm frequency, with an sea surface temperature rise of 0.7 degrees Fahrenheit leading up to 1930 and a similar rise leading up to 1995 and continuing even after.
The Holland and Webster study indicates that natural cycles are probably not the entire cause of the increase in hurricane numbers because the increase has happened across the last century rather than oscillating in tandem with a natural cycle.