A new study (pdf) says there is no need to worry about whether 414 U.S. cities will lose at least 50% of their populated area to rising seas from climate change in the future. Their fate is already sealed. The only questions are how many cities will join them (could be as high as 1,544) and when.

How much sea rise we experience depends on how much carbon we spew into the atmosphere. We have already done enough to guarantee serious problems for a lot of cities, including New York, Miami and, of course, New Orleans.

California’s Sacramento, Stockton, Hayward, Elk Grove, Richmond, Oxnard, Long Beach and Huntington Beach are among the doomed cities cited in the study published this week in the Proceedings of the National Academy of Sciences. The research team, led by Climate Central in conjunction with Anders Levermann of the Potsdam Institute of Climate Impact Research, predicted various dismal scenarios that added cities to the list and calculated levels of devastation depending on what temperature we cook the planet.

The eight California cities are among 44 cities with populations above 100,000 that are locked in to having at least 25% of their populated areas eventually underwater under certain conditions. They are part of a baseline scenario that assumes the “unstable” West Antarctic Ice Sheet (WAIS) doesn’t collapse and force ocean levels higher, which many scientists think is inevitable. Only Stockton, Sacramento and Huntington Beach make a list of 25 cities that would lose at least 50% and no California cities are projected to lose 100%.

The list of cities doesn’t change much if WAIS crumbles into the sea, but the locked-in doomsday is greatly accelerated. Stockton is already locked in to a 25% loss if nothing changes, and if things don’t improve by 2045, they would lock in to a 50% loss. If WAIS crumbles, Stockton would immediately be locked in to a 50% loss.

Sacramento is in a little better shape than Stockton. The capital would lock in in 2050 to a 25% loss under baseline conditions and no improvement in emissions. Sacramento would lock in to a 50% loss in 2075. If WAIS collapses, the capital would immediately lock in to a 25% loss and a 50% loss in 2030.

Some portion of each city survives under all the scenarios.

Michael Oppenheimer, a Princeton University climate researcher, told the Washington Post: “The potential magnitude of sea-level rise is staggering. In the short term, it risks serious disruption of life along the coast while in the long term, it could lead to obliteration of a large and priceless amount of our cultural heritage, worldwide.”

If the world does nothing about reducing carbon emissions, the study projects 26 million U.S. homes might end up under water. More than 1,500 municipalities could have half their residents inundated.

The report is far more confident about its predictions of eventual devastation than it is about the timetable. It could take a millennium for some of the cities to go down, but some could go down before the end of the century.  

The researchers created a number of scenarios involving carbon emissions and temperatures, but added a new wrinkle to calculations of rising oceans. If WAIS collapses, as many scientists think is inevitable, ocean levels will rise significantly.

They sought to measure when municipalities would be locked into an underwater fate, not predict when they would go under. Mitigating circumstances could forestall the inevitable for awhile.  

The researchers used their data to create interactive maps that can provide hours of entertainment. “You can watch threats unfold nationwide or for individual states, and track the potential fate of each municipality,” according to Climate Central.   

–Ken Broder

To Learn More:

It's Too Late to Save over 400 U.S. Cities from Rising Seas, Scientists Say (by Reynard Loki, AlterNet)

Want to Know How Sea Level Rise Will Impact Your Hometown? There’s a Map for That (by Natasha Geiling, ThinkProgress)

This Is How Rising Seas Will Reshape the Face of the United States (by Chris Mooney, Washington Post)

Sea Level Rise Will Swallow Miami, New Orleans: Study (by Kerry Sheridan, Agence France Presse)

Miami and New Orleans Among 400 U.S. Cities said to Be Doomed by Rising Sea Levels (by Noel Brinkerhoff, AllGov)

“Mapping Choices Launched to Visualize Carbon Choices (Climate Central)

Carbon Choices Determine US Cities Committed to Futures Below Sea Level (by Benjamin H. Strauss, Scott Kulp and Anders Levermann, Proceedings of the National Academy of Sciences)