Hotter planet would mean regular 'Katrina' storms
Katrina-scale storm surges could become 10 times more frequent with just a two degree rise in global temperatures, a study has found.
Hurricane Katrina was officially the most destructive storm ever to strike the US.
An estimated 1,836 people lost their lives and millions more were left homeless by the cyclone which pounded New Orleans and other Gulf of Mexico communities in 2005.
Much of the devastation was caused by storm surges whipped up by the winds, which saw sea levels rise by between 24 and 28 feet along a 20-mile stretch of the Mississippi coast.
New research suggests that even moderate climate change is likely to make such extreme storm surges more common.
Since 1923, there has been a Katrina-magnitude storm surge roughly every 20 years. With less than half a degree Celsius of warming, this frequency could double, the study shows.
A 1C rise produces a three to four-fold rate increase and if temperatures rise by 2C – the "safe" limit set by experts – extreme storm surges become 10 times more common.
"This means there will be a Katrina magnitude storm surge every other year," said Danish climate scientist Dr Aslak Grinsted, who led the research reported in the journal 'Proceedings of the National Academy of Sciences'.
The study involved comparing historical storm surges with a range of different climate model predictions taking into account natural phenomena such as El Nino, which warms the eastern Pacific and affects global temperature.