From the northern reaches of the Atlantic seaboard to the Mississippi Delta region of the Gulf of Mexico coast, erosion is in the news this summer. In late June, an unusual summer northeaster took a big bite out of Cape Cod's sandy beaches. The storm narrowed several popular stretches of beach to just a few yards wide, destroyed the nesting sites of endangered piping plovers, and signed the death warrants for several old beachfront houses. This report in the Boston Globe describes the storm and its effects (" Stormy week gnaws at Outer Cape beaches," by Peter Schworm), while this story (with photos) details the plight of five cottages, or "camps," in the town of Chatham, Massachusetts (" In Chatham, an austere utopia yields to a relentless tide," by Brian MacQarrie). Of twelve original cottages still left on the Chatham shore, five had to be demolished after the storm undermined the fragile land supporting their foundations. But this summer's Cape Cod erosion — just one more episode in a continuing shrinkage of the Cape's seaward edge — pales in comparison to the future in store for coastal Louisiana, according to a recent paper by two Louisiana State University researchers in the journal Nature Geosciences (" Drowning of the Mississippi Delta due to insufficient sediment supply and global sea-level rise," by Michael D. Blum and Harry H. Roberts). The New York Times covers the story (" Dams Are Thwarting Louisiana Marsh Restoration, Study Says," by Cornelia Dean), as does The Christian Science Monitor (" Will much of New Orleans be underwater by 2100?" by Peter N. Spotts). In the usual course of natural events, explain Blum (LSU Department of Geology and Geophysics) and Roberts (LSU Department of Oceanography and Coastal Sciences), river deltas like the mighty Mississippi's outflow plain are replenished by sediment washed from the mainland by rain, and borne down the river to be deposited at the river's mouth. But with man's intervention, half or more of the usual sediment load the river would naturally carry is now trapped and detained upstream, falling out as silt in reservoirs behind artificial dams. In short, there's just not enough mud coming down the Big Muddy to rebuild the swampy land around the Big Easy. "Sustaining existing delta surface area would require 18–24 billion tons of sediment, which is significantly more than can be drawn from the Mississippi River in its current state," report Blum and Roberts. And even if all the upstream dams were breached and the silt allowed to flow, it wouldn't be enough, they say — because sea levels in the Gulf of Mexico are expected to rise. "We conclude that significant drowning is inevitable, even if sediment loads are restored, because sea level is now rising at least three times faster than during delta-plain construction," the scientists write. Over the course of the coming century, saving the Mississippi Delta in its current state, including New Orleans and surrounding Parishes, is out of the question, Blum and Roberts write. By 2100, the paper predicts, sea levels will be 2.6 to 3.9 feet higher than today. The best that can be hoped for, the scientists say, is to salvage part of what currently exists — and that can only happen if selected levees upstream of New Orleans are breached, to allow the river to carry its load of mud into existing bayous where the silt will be trapped and retained, rather than washed far out to sea and dumped in deep water. For video coverage of the Louisiana coastal wetlands situation, check out this YouTube video from Assignment:Earth. Diverting the Mississippi to build wetlands and solid ground, researchers Blum and Roberts acknowledge, is more than just a civil engineering problem. Reports the New Orleans Times-Picayune, "The problems with major diversions would be both political and cultural, Roberts warned, as each diversion would protect only a limited number of communities and would disrupt traditional commercial and recreational fishing." The Times-Picayune article is here (" LSU researchers: coastal restoration projects doomed to fail," by Mark Schleifstein). New Orleans' tenuous future has not stopped some people from moving back to the city, however. A U.S. Census report released last month indicates that the city's population grew by just over 8% last year (by far the fastest growth rate of any city in the nation), as the total number of inhabitants jumped by 24,000. However, the 8% rebound fell far short of making up for the exodus caused by 2005's Hurricane Katrina: New Orleans still remains 35% short of its year 2000 census count. The Times-Picayune covers the report here (" New Orleans is the fastest-growing big city; population increases 8.2 percent in year," by Michelle Krupa). But the short run, at least, inhabitants of the imperiled Delta region haven't given up on the idea of restoring their protective wetlands. In late June, Louisiana Governor Bobby Jindal cheered the release of $368 million in Federal funds to pay for coastal wetland restoration, according to local news station WWLT (" Massive investment in coastal restoration spurs hope," by Susan Edwards). Officials are aware of the Nature Geosciences paper and its implications, but in the words of Windell Curole, director of the South Lafourche Levee District, "Maybe, hopefully, things will be better than what we think, but if we stand around and do nothing then you know we have nothing but bad times in front of us."