So it is not surprising that while the inure than a dozen major global climate models in use around the world tend to agree on the broadest phenomena, they differ wildly when it comes to regional effects. And, says Robert Cess, a climate modeler at the State University of New York at Stony Brook, "The smaller the scale, the bigger the disagreement."
That makes it extremely hard to get national and local governments to take action. Says Stephen Leatherman, director of the Laboratory for Coastal Research at the University of Maryland, "Unless you can put something down on paper and show the effects on actual locations— even actual buildings—then it's just pie in the sky."
There are, however, some consequences of a warming Earth that will be universal. Perhaps the most obvious is a rise in sea level. "If we went all out to slow the warming trend, we might stall sea level rise at three to six feet," says Robert Buddemeier of Lawrence Livermore National Laboratory, who is studying the impact of sea- level rise on coral reefs, "But that's the very best you could hope for." And a six- foot rise, Buddemeier predicts, would be devastating.
It would, for one thing, render almost all low coral islands uninhabitable. "Eventually," Buddemeier says, "a lot of this real estate is going to go underwater," For places like the Marshall Islands in the Pacific, the Maldives off the west coast of India, and some Caribbean nations, this could mean nothing less than national extinction. "You're really looking at a potential refugee problem of unprecedented dimensions," says Buddemeier. "In the past, people have run away from famine or oppression. But they've never been physically displaced from a country because a large part of it has disappeared."
Coastal regions of continents or larger islands will also be in harm's way, particularly towns or cities built on barrier islands and the fertile flat plains that typically surround river deltas. Bangladesh, dominated by the Ganges-Brahmaputra-Meghna Delta, is the classic case, says Buddemeier. "It's massively populated, achingly poor, and something like a sixth of the country is going to go away."
Egypt will be in similar trouble, according to a study by economist James Broadus and several colleagues at Woods Hole Oceanographic Institution. Like the Ganges-Brahmaputra-Meghna, the soft sediments of the Nile Delta are subsiding. Given even an intermediate scenario for sea-level rise by the year 2050, Egypt could lose 15 percent of its arable land, land that currently houses 14 percent of its population and produces 14 percent of its gross domestic product.
One mitigating factor for some coastal nations that are still developing, such as Belize and Indonesia, is that they generally have committed fewer resources to the coastline than their developed counterparts—Australia, for example, or the United States, with such vulnerable cities as Galveston and Miami. "Developed countries have billions invested in a very precarious, no-win situation," Buddemeier says. "The less developed countries will have an easier time adapting."
