Next Global-Warming Victim: Centuries-Old Shipwrecks

At the bottom of the Baltic Sea, history sits largely intact. Because shipworms don't care for these cold, low-salt waters, shipwrecks can endure for centuries without great decay. The Vasa, a famous Swedish warship that sank in Stockholm harbor in 1628, was in terrific condition when engineers raised it from the depths more than 300 years later. But, scientists now warn, those conditions could be coming to an end due to global warming.