coastal cities, with their massive buildings, complex infrastructures, and road networks, compress the underlying and surrounding land surfaces. The sea level rises as a result, and seawater moves inland. Fifty-four percent of sea level rise around Norfolk, Virginia, is due to sinking land. Intense development and highrise construction are causing large segments of Miami-Dade County in southern Florida to sink by as much as 2 inches annually.

5. The warm Gulf Stream compounds sea level problems in Florida and large portions of the U.S. east coast. The Stream flows northward of Florida's east coast, a giant "conveyor belt" that is affected by melting

Tuktoyaktuk, Northwest Territories, Canada

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A Concrete Solution

Rising sea levels are threatening not only dense population centers but also small, remote communities, close to or below sea level. Arctic peoples along the northern coastlines of the United States and Canada face serious risks. Their ancestors moved constantly, using temporary summer camps. Today, these transitory encampments are occupied year-round, many of them on low barrier islands. Once protected by permafrost and sea ice, they are now at risk from wave damage during storms and aggressively climbing sea levels.

Tuktoyaktuk is an Inuvialuit village on the Arctic Ocean in Canada's Northwest Territories. For generations, it has been a base for beluga whale and caribou hunting. Shrinking ice (by about 8 percent per year since the 1960s) and rising sea levels have increased the threat of storm surges. With the permafrost melting, the community is endangered. The inhabitants are moving buildings from vulnerable spots to safer ground and considering building up the island; one solution involves stacking concrete slabs on the beach.