Is this ‘age of the delta’ coming to an end? Scientists worry about recent rapid losses

THE LAND NEAR the mouth of the Mississippi River is barely land at all. Muddy water forks into a labyrinth of pathways through a seemingly endless expanse of electric-green marsh grass, below skies thick with birds. Shrimp and crabs wriggle in the water below, and oak and cypress sprout from wet soils on higher grounds. Stretching for more than a hundred miles along the coast of Louisiana, this is one of the world’s largest, and most famous, river deltas.

Similar landforms — flat and wet and rich with wildlife — have built up wherever rivers dump their mud and sand into shallow oceans. There are thousands of such deltas across the world, ranging in size from just a few acres to, in the case of the Mississippi River’s, thousands of square miles. Many of these places, including the marshes in Louisiana, are now disappearing, often quite rapidly.