In another sign of global warming's growing influence on weather patterns around the world, a team of climate scientists have found that the number of storms in the Atlantic has dramatically increased over the past century. They attribute this upswing — a doubling in the average number of yearly storms since 1905 — to a rise in sea surface temperatures in the Atlantic (0.7°C over the past century).
Greg Holland, a climate scientist of the US National Center for Atmospheric Research in Boulder, Colorado, and one the lead authors on the study with Georgia Institute of Technology's Peter Webster, identified three separate climate regimes in the last century: the first, extending from 1905 to 1930, had an average of 6 storms each year (4 of which were hurricanes); the second, from 1931 to 1994, had a higher average of 10 storms (5 of which were hurricanes); the third, from 1995 to 2005, had a record average of 15 annual storms (8 of which were hurricanes). Holland and his colleagues believe this average number could still rise further within this century.
"These numbers are a strong indication that climate change is a major factor in the increasing number of Atlantic hurricanes," said Holland. "We are of the strong and considered opinion that data errors alone cannot explain the sharp, high-amplitude transitions between the climatic regimes, each with an increase of around 50 percent in cyclone and hurricane numbers, and their close relationship with SSTs."
While the ratio of hurricanes to all Atlantic tropical cyclones has remained mostly unchanged over the last few decades — accounting for close to 55% of all cyclones — the ratio of major hurricanes (with maximum sustained winds of at least 110 mph) to weaker hurricanes and storms has risen significantly in recent years.
Though there remain some prominent detractors, notably Colorado State University's meteorologist William Gray, climate science is slowly but surely moving towards a new consensus in the hurricane-climate debate, with global warming being increasingly blamed for some of the unprecedented weather patterns we've witnessed over the last few years. Greg Holland, a former student of Gray's and once global warming skeptic, has evidently changed his views quite a bit since his graduate days.
Via ::Guardian Unlimited: Big rise in number of Atlantic storms blamed on global warming (blog), ::UCAR: Frequency of Atlantic Hurricanes Doubled Over Last Century; Climate Change Suspected (press release)