Climate change may be a back-burner issue in Washington,.but for some experts, worrying about long-term changes in the earth's climate is a career. Last week 170 of those experts met in Fort Lauderdale, Florida, for a conference about rising sea levels. Under discussion: The vulnerability of their low-lying location to long-term encroachment by ocean waters.

Members of the Association of Climate Change Officers "talked about the challenging future faced by South Florida, where rising seas will lead to more frequent floods, threats to drinking water, and the heavy financial burden of building sea walls, protecting well fields, and improving drainage systems," reports the Sun Sentinel (" Sea level rise in South Florida: expect floods, sea wall woes," by David Fleshler).

Sea level has risen 9 inches in the past century along the Florida coast; planners anticipate another 9 to 24 inches of rise by 2060. That's enough to affect inland residents, not just the coastal towns, Broward County director of natural resource planning and management Jennifer Jurado said: "Water will push up through storm drains connected to the ocean. And as sea levels rise, salt water will continue encroaching on South Florida's underground aquifer, threatening to knock out wells used for drinking water, a process that is well underway."

In New York, mayor Michael Bloomberg has unveiled an ambitious — and expensive — plan to harden the city against the power of future storms that whose tides and waves will come on top of a long-term trend toward higher sea level. But the sort of dikes, dunes, and barriers Bloomberg envisions would likely be ineffective in Florida, as National Geographic reports (" New York's Sea-Level Plan: Will It Play in Miami?" by Tim Folger).

"Miami rests on a foundation of highly porous limestone," National Geographic points out. "Seawater would flow unimpeded beneath any levee or storm surge barrier." And with its high-value built environment, the city tops a list compiled a few years ago by the Organisation for Economic Co-operation and Development (OECD), an international group of developed nations, of cities with assets at risk from rising seas.

The problem is global, National Geographic notes: The OECD report says "40 million people and $3 trillion in assets are already vulnerable to coastal flooding in cities around the world. By 2070, the OECD paper said, those numbers could rise to 150 million people and $35 trillion — and that's assuming a sea-level rise of just 20 inches."

In Miami, as in other cities around the planet, trouble is at the doorstep. "It's already contaminating Florida's underground water supply, and it regularly erupts from Miami's sewers during 'king tides,' when the sun and moon exert their most powerful tidal pull on Earth," National Geographic reports. "The problem is only going to get worse: By the century's end large parts of Florida may be underwater."

An overview in the Economist of London observes that Florida is hardly unique, even among U.S. locations (" Coastal cities and climate change: You're going to get wet"). "Houston, the centre of America's petrochemical industry, and Norfolk, Virginia, home to its largest naval base, could also be in trouble," notes the magazine. "So could some of the barrier islands along the Atlantic coast, such as North Carolina's Outer Banks, and traditional Atlantic maritime regions such as Maryland's Eastern Shore. These two areas, like South Florida, have seen sharp rises in population and development."

Responses vary, from Mayor Bloomberg's ambitious activism to the avoidance response of the North Carolina legislature, which passed a resolution outlawing "scenarios of accelerated sea-level rise unless such rates are ... consistent with historic trends" (a strategy the Economist compares to "ordering meteorologists to predict the weather not by looking at the radar image of a hurricane barrelling towards the coast, but by consulting the Farmer's Almanac"). It's a contrast with the official stance in Florida, where "four of the southernmost counties — which include the state's three most-populous ones, accounting for more than a quarter of its total population — have formed the Southeast Florida Regional Climate Change Compact," the Economist reports. "These counties share data, work together on legislation and seek funding in concert."

But in the view of some experts, even the most proactive coastal armoring or elevating projects won't be enough to fend off the inevitable — especially in the nation's most vulnerable coastal areas. Said Duke professor Orrin Pilkey, co-author of the book The Rising Seas, to National Geographic: "The can-do attitude won't work on the Mississippi delta. What we should be planning on is how to get out of there gracefully."