Mississippi Delta marshes in a state of irreversible collapse, Tulane study shows

Given the present-day rate of global sea-level rise, remaining marshes in the Mississippi Delta are likely to drown, according to a new Tulane University study. A key finding of the study, published in Science Advances is that coastal marshes experience tipping points, where a small increase in the rate of sea-level rise leads to widespread submergence.

The loss of 2,000 square miles (5,000 km2) of wetlands in coastal Louisiana over the past century is well documented, but it has been more challenging to predict the fate of the remaining 6,000 square miles (15,000 km2) of marshland. The study used hundreds of sediment cores collected since the early 1990s to examine how marshes responded to a range of rates of sea-level rise during the past 8,500 years.

“Previous investigations have suggested that marshes can keep up with rates of sea-level rise as high as half an inch per year (10 mm/yr), but those studies were based on observations over very short time windows, typically a few decades or less.”

The researchers found that in the Mississippi Delta most marshes drown in a few centuries once the rate of sea-level rise exceeds about one-tenth of an inch per year (3 mm/yr). When the rate exceeds a quarter of an inch per year (7.5 mm/yr), drowning occurs in about half a century.

Read the full article from Tulane University here.