Extreme hurricane storm surge events are going to become at least 10 times more common in the near future as a result of climate change, new research from the Niels Bohr Institute has found. Storm surge events on the scale of Hurricane Katrina will be expected to occur once every two years with a 2C rise in temperatures. If the temperature rises more than 2C the frequency will continue rising also. Hopefully by then people will not be building large developments in vulnerable coastal areas such as New Orleans.
The new research was done using a somewhat novel approach. Rather than using models based on regional sea temperatures, or on the differences between the regional sea temperatures and the average temperatures in the tropical oceans, the two most-used methods, a new approach was used.
“Instead of choosing between the two methods, I have chosen to use temperatures from all around the world and combine them into a single model,” states climate scientist Aslak Grinsted, from the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
The new approach “takes into account the individual statistical models and weights them according to how good they are at explaining past storm surges. In this way, he sees that the model reflects the known physical relationships, for example, how the El Niño phenomenon affects the formation of cyclones.”
During the past 90 years, a ‘Katrina’ magnitude storm surge occurred roughly every 20 years. But with rising temperatures, and it’s associated effects, that will increase significantly.
“We find that 0.4 degrees Celcius warming of the climate corresponds to a doubling of the frequency of extreme storm surges like the one following Hurricane Katrina. With the global warming we have had during the 20th century, we have already crossed the threshold where more than half of all ‘Katrinas’ are due to global warming,” says Aslak Grinsted.
“If the temperature rises an additional degree, the frequency will increase by 3-4 times and if the global climate becomes two degrees warmer, there will be about 10 times as many extreme storm surges. This means that there will be a ‘Katrina’ magnitude storm surge every other year,” says Aslak Grinsted.
Image Credit: Aslak Grinsted, Niels Bohr Institute