Rising sea level to submerge Louisiana coastline by 2100, study warns

Suzanne Goldenburg in the Guardian (UK): A vast swath of the coastal lands around New Orleans will be underwater by the dawn of the next century because the rate of sediment deposit in the Mississippi delta can not keep up with rising sea levels, according to a study published today. Between 10,000 and 13,500 square kilometres of coastal lands will drown due to rising sea levels and subsidence by 2100, a far greater loss than previous estimates.

For New Orleans, and other low-lying areas of Louisiana whose vulnerability was exposed by hurricane Katrina, the findings could bring some hard choices about how to defend the coast against the future sea level rises that will be produced by climate change. They also revive the debate about the long-term sustainability of New Orleans and other low-lying areas.

Scientists say New Orleans and the barrier islands to the south will be severely affected by climate change by the end of this century, with sea level rise and growing intensity of hurricanes. Much of the land mass of the barrier island chain sheltering New Orleans was lost in the 2005 storm.

But the extent of the land that will be lost is far greater than earlier forecasts suggest, said Dr Michael Blum and Prof Harry Roberts, the authors of the study. "When you look at the numbers you come to the conclusion that the resources are just not there to restore all the coast, and that is one of the major points of this paper," said Roberts, a professor emeritus of marine geology at Louisiana State University.

Blum, who was formerly at Louisiana State University, now works at Exxon. "I think every geologist that has worked on this problem realises the future does not look very bright unless we can come up with some innovative ways to get that sediment in the right spot," said Roberts. "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."….

An 1866 painting of a Louisian bayou by Joseph Rusling Meeker