photo: Natalie Maynor via flickr
By then end of this century, somewhere between 3,800-5,200 square miles of coastal land around New Orleans are likely to be submerged as global sea level rise outpaces the rate of sediment deposited by the Mississippi river, an area much larger than previously predicted. That's the word coming from researchers Michael Blum and Harry Roberts, writing in the journal Nature Geoscience (subscription req'd):The researchers say that retaining existing delta surface area would require 18-24 billion tons of sediment deposition, something made critically more difficult because the sediment load of the Mississippi has been reduced by 50% due to dam construction in the Mississippi River basin.
They conclude that "significant drowning is inevitable" and that land areas now below 1 meter in elevation will become open water or marsh.
What to Save and What Not to Save
All of which means that we really ought to be talking about whether we ought to be considering moving development away from the coastline, and not spending the effort to save that which looks increasingly likely we'll have to consign to the sea.
The Guardian quotes Blum as saying,
I think every geologist that has worked on this problem realizes the future does not look very bright unless we come up with some innovative ways to get that sediment in the right spot. For managers and people who are squarely in the restoration business, this is going to force them to make some very hard decisions about which areas to save and which areas you can't save.
Global Sea Level Rise
Sea Level Rise Best Case Scenario: 50cm Rise, 10% of World Population Hit
Sea Lever Rise Predictions Too Low, No Abrupt Release of Methane: US Climate Change Science Program
See For Yourself: Interactive Sea Level Rise Explorer