PUBLIC MARKS with tags america & doom

It's the fabled Gulf Stream. Traveled by whalers and sailors for centuries but never accurately charted until it aroused the curiosity of none other than Benjamin Franklin, the current has emerged in the last decade as a focal point for scientists studying global climate change. The concerns about the state of the ocean today run so deep that an unprecedented international effort is underway from the Straits of Florida to Greenland to track changes in the North Atlantic. And the Gulf Stream is a narrow but critical piece of the larger system: It moves warm surface water from the tropics toward the North Pole and pumps cold water back toward the equator in a deep-sea current -- a mechanism scientists have come to call the North Atlantic ``conveyor belt.'' Scientists believe if the Gulf Stream were to slow or take a more southerly route, the change could disrupt the system and the world's weather. Over time -- how much time is a key uncertainty in the theory -- the North Atlantic could cool, turning Europe and eastern North America colder as the rest of the world heated up.