(Bloomberg View) -- If the latest projections about thepace and scope of sea-level rise are even close to accurate, thenget ready for a fight — not starting in decades, but right now— over which communities get saved, and who pays for it.

Detailed online mapping tools, including the National Oceanicand Atmospheric Administration's Sea Level Rise map and thenonprofit ClimateCentral's Surging Seas project, can tell us which states wouldbe hit the hardest by the effects of melting Antarctic glaciers andother environmental changes.

States in most danger are among the poorest

Two things jump out. First, thanks to the vagaries of topography aswell as tidal and development patterns, the social and financialburdens that the coastal states will have to bear are wildlyunequal from one to the next. Second, the states in the most dangerare generally among the country's poorest.

There are different ways of measuring risk. Start with the mostobvious: How much land would each state lose if sea levels rose bysix feet, the amount projected by 2100 in a recent paper? Theclearest takeaway is the disproportionate vulnerability ofLouisiana, and to a lesser degree Florida and Delaware.

But just as interesting is that even assuming a sea-level riseof six feet, most coastal states would lose less than 1% of theirland. Among the 24 coastal states plus the District of Columbia,only five would face a loss of 5% or more.

Competition for federal assistance

Of course, what's of greater worry for policy makers is what's onthat land.

For most coastal states, a six-foot rise in sea levels would beeconomically challenging but not catastrophic. It's far differentfor a handful of states, most of them in the Southeast, most ofthem poor. Of the seven with more than 10% of their property value at risk fromthat magnitude of sea rise, all but New Jersey are in the bottomhalf of the national per-capita income distribution.

So why does it matter how the hazards of rising sea levels varybetween states? The ones that are most affected will demand federalassistance — for sea walls, levees, more resilient roads andbridges, and, if all else fails, money to rebuild fartherinland.

Those projects are enormously expensive. After HurricaneKatrina, the U.S. Army Corps of Engineers spent $14 billionrebuilding the levees that guard New Orleans. In southeasternVirginia, the Hampton RoadsPlanning District Commission estimated that coping with threefeet of sea-level rise would cost between $12 billion and $87billion.

Political and technical constraints

Finding that kind of federal money for a handful of communities isone thing. But as requests for help increase, the constraints onproviding it will be political as much as technical. Money spent onthe needs of coastal states struggling with rising sea levels ismoney the federal government can't spend on Social Security,highways, education or anything else.

It's not hard to imagine those coastal states making commoncause in arguing that the federal government has a responsibilityto help. South Carolina, Louisiana and Alabama may oppose a strongfederal government when it comes to social programs. They may feelotherwise when the activity in question is saving their cities andtowns.

Inland states will probably view the federal government'sobligations differently. And so sea-level rise has the potential toaugment, in new and unpredictable ways, the schisms that alreadyshape U.S. politics: urban versus rural; red versus blue; wetversus dry.

What happens to the Republican Party, for example, if thecoastal Deep South becomes the leading advocate for big governmentand a carbon tax? And how much will the vast majority of voters— who face much less risk of losing their homes,even a century from now — be willing to offer those whodo?

This column does not necessarily reflect the opinion of theeditorial board or Bloomberg LP and its owners.

Copyright 2018 Bloomberg. All rightsreserved. This material may not be published, broadcast, rewritten,or redistributed.