The future of the brown pelican
Raccoon Island, a barrier isle an hour's boat ride off the coast of Louisiana, is one of the few remaining refuges for the iconic brown pelicans. A dozen years ago, there were 15 low-lying islands with nesting colonies of Louisiana's state bird. But today, just six islands in the state harbor brown pelican nests — the rest have disappeared under water from subsidence and rising seas from climate change. "We are ground zero for looking at the effects of sea level rise because the coast is sinking at the same time, sea levels are going up," said Paul Leberg of University of Louisiana at Lafayette: The vanishing islands threaten one of the last century's most celebrated conservation success stories — the decades-long effort to bring the pelicans back from the edge of extinction driven by the pesticide DDT. "We're seeing signs like we saw back then, but we're not responding to them like we should," said Jimmy Nelson at the University of Louisiana at Lafayette. The same forces swallowing up coastal islands are also causing southern Louisiana's saltwater marshes to disappear faster than anywhere else in the country. Scientists estimate Louisiana loses one football field worth of ground every 60 to 90 minutes. Protecting what's left depends on continuous human intervention. Today one side of Raccoon Island is ringed by six man-made breakwaters that divert tides. Erosion is a natural process, and over the course of thousands of years, most barrier islands rise and fall. Unlike volcanic islands, there is no bedrock here, only layers of silt washed down the Mississippi Delta. But sea rise and increased storm frequency and intensity with climate change accelerate the pace. And the islands have been starved of new Mississippi sediment because the river's course has been controlled since the 1940s by levees to prevent flooding and aid shipping. Every few years, government agencies work to restore and maintain some barrier islands. The money comes from a legal settlement after the 2010 Deepwater Horizon oil spill. But it won't last forever — and many sinking islands aren't restored at all.
