Louisiana: This Ain’t Normal!
Popular Science took on the question that is on most (science-accepting), people. Louisiana has been hot with at least 24 inches of water in 24 hours, with Watson, Louisiana topping out at 31 inches. The American Red Cross declared it the worst crisis since Hurricane Sandy.
The explanation is very simple for those of us who understand how climate change is changing the “normal” patterns of precipitation patterns. It’s pretty simple really – when it’s a warmer world, there is more evaporation and therefore water vapor in the atmosphere. So when it rains, it deluges.
From the Popular http://www.popsci.com/Science piece:
The record-breaking deluge was fueled in turn by a record-breaking amount of water vapor in the atmosphere above the southeastern Louisiana. The National Weather Service reported water vapor levels in the atmosphere so high they came close to breaking the Weather Service chart.
But for Louisiana had the double whammy as the article explains:
In the particular case of the Louisiana rains, global warming landed a double whammy. Not only was a warmer atmosphere ready to hold more water, the waters of the Gulf were able to evaporate more easily due to unusually warm seas, a long-term trend also driven by global warming. The storm system was fed by moist winds coming off the Gulf coast where sea surface temperatures were running hot, bumped up by global warming. In the days immediately before the storm, sea surface temperatures in the Gulf hovered near 90°F, 4-5°F above average.
So, you don’t have to be a climate scientist to recognize that warmer waters (like 90 degrees) is going t o evaporate quickly, and when it rains, it deluges.
It’s part of a larger regional feature of increased water vapor in the Unites States. NASA and NOAA have studied regional changes in precipitation. In general, we are getting wetter. The jet streams have changed, and have created some “ridiculously ridges” that have cut off the natural precipitation in California (like at least a 1,200 year drought). But here is the map of our new normal precipitation.
So we have a new normal. We will see more extreme precipitation events like in Louisiana. The question is: are we prepared for it?