Report: Global Warming Doubles Extreme Coastal Flood Risk Across U.S., Seas Projected to Rise a Foot by 2050

Rising Sea Levels Threaten Millions by Boosting Storm Surges

This map shows the odds of floods at least as high as historic once-a-century levels, occurring by 2030, based on Climate Central research. The two bars extending from each study point contrast odds estimates incorporating past and projected sea level rise from global warming (red bars), and odds estimates not incorporating this rise (blue bars). Global average sea level has increased more than eight inches since 1880, and the rise is accelerating. Most or all of the rise can be attributed to global warming, which warms and expands global oceans, and causes glaciers and ice sheets to decay.

A Climate Central repost, study here, interactive map here

Sea level rise due to global warming has already doubled the annual risk of coastal flooding of historic proportions across widespread areas of the United States, according to a new report from Climate Central. By 2030, many locations are likely to see storm surges combining with sea level rise to raise waters at least 4 feet above the local high-tide line. Nearly 5 million U.S. residents live in 2.6 million homes on land below this level. More than 6 million people live on land below 5 feet; by 2050, the study projects that widespread areas will experience coastal floods exceeding this higher level.

Titled “Surging Seas,” the report is the first to analyze how sea level rise caused by global warming is compounding the risk from storm surges throughout the coastal contiguous U.S. It is also first to generate local and national estimates of the land, housing and population in vulnerable low-lying areas, and associate this information with flood risk timelines. The Surging Seas website includes a searchable, interactive online map that zooms down to neighborhood level, and shows risk zones and statistics for 3,000 coastal towns, cities, counties and states affected up to 10 feet above the high tide line.

In 285 municipalities, more than half the population lives below the 4-foot mark. One hundred and six of these places are in Florida, 65 are in Louisiana, and ten or more are in New York (13), New Jersey (22), Maryland(14), Virginia (10) and North Carolina (22). In 676 towns and cities spread across every coastal state in the lower 48 except Maine and Pennsylvania, more than 10% of the population lives below the 4-foot mark.

Tidal gauge records show that the sea has already risen 8 inches globally during the last century, and projections point to a steep acceleration. “Sea level rise is not some distant problem that we can just let our children deal with. The risks are imminent and serious,” said report lead author Dr. Ben Strauss of Climate Central. “Just a small amount of sea level rise, including what we may well see within the next 20 years, can turn yesterday’s manageable flood into tomorrow’s potential disaster. Global warming is already making coastal floods more common and damaging.

In addition to the Surging Seas report and website, Climate Central is releasing fact sheets laying out the risks for each coastal state. Staff scientists (Ben Strauss, Claudia Tebaldi, Remik Ziemlinski) have also authored two peer-reviewed studies being published March 15th in the scientific journal Environmental Research Letters, with co-authors at the University of Arizona (Jeremy Weiss, Jonathan Overpeck) and the National Oceanic and Atmospheric Administration (Chris Zervas).  In addition to hosting the map tool, the national reportstate fact sheets, and the peer-reviewed papers, the website,, includes downloadable data for all the cities, counties and states studied; embeddable widgetsrepublishable graphics; and links to dozens of local, state and national planning documents for coping with rising seas.

The website also shows how the threat from climate change-driven sea level rise and storm surge is expected to increase over time at 55 tidal gauges around the U.S. and near most major coastal cities. At the majority of these gauges, floods high enough to formerly be called worse than once-a-century events have more than doubled in likelihood.

Land, housing and population vulnerability estimates are based on 2010 Census data and on land elevations relative to potential water levels, and do not take into account potential protections.  However, properties behind walls or levees may suffer enhanced damage when defenses are overtopped, or during rainstorms, because the same structures that normally keep waters out can keep floodwaters in once they arrive.

“Escalating floods from sea level rise will affect millions of people, and threaten countless billions of dollars of damage to buildings and infrastructure,” Strauss said. “To preserve our coastal towns, cities and treasures, the nation needs to confront greenhouse gas pollution today, while also preparing to address sea level rise that can no longer be avoided.

— Climate Central is a non-profit research and journalism organization providing authoritative and up-to-date information to help the public and policymakers make sound decisions about climate and energy.

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18 Responses to Report: Global Warming Doubles Extreme Coastal Flood Risk Across U.S., Seas Projected to Rise a Foot by 2050

  1. Leif says:

    Another factor that is seldom acknowledge is that stronger storms, (also predicted from climatic disruption), have lower low pressure centers which have a “soda straw” effect on water levels. Last years “Frankenstorm” here in the PNW raised the predicted high tides in the area almost two feet above normal. For days on end. Why, oh why, are “We the People” left holding the bag here as Corpro/People Profit from the Pollution of the COMMONS? Corpro/People must be taught to play nice with others.

  2. Facts don’t win arguments with those who are emotionally attached to something other than facts. As Asimov wrote:

    “Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that ‘my ignorance is just as good as your knowledge.’”

  3. Doug Bostrom says:

    Joe, would you mind updating this post for the benefit of the New York Times and its readers?

    In an otherwise excellent article, NYT accidentally implies that Myron Ebell is a climate researcher:

    The handful of climate researchers who question the scientific consensus about global warming do not deny that the ocean is rising. But they often assert that the rise is a result of natural climate variability, they dispute that the pace is likely to accelerate, and they say that society will be able to adjust to a continuing slow rise.

    Myron Ebell, a climate change skeptic at the Competitive Enterprise Institute, a Washington research group, said that “as a society, we could waste a fair amount of money on preparing for sea level rise if we put our faith in models that have no forecasting ability.”

    Myron Ebell:

  4. Joe Romm says:

    I’m doing a separate post on that.

  5. Gingerbaker says:

    “Seas Projected to Rise a Foot by 2050”

    What is the baseline for that one foot rise – 1880?

  6. Peter says:

    A 1 foot rise in sea level will leave most beaches in New England with water and no sand. Imagine a hot day in 2040- over 100 degrees with stifling humidly- yet the beaches are gone- replaced by a sea wall- another nice future we bequeath our children.

  7. Mark Shapiro says:

    Thanks in advance, Joe. It would take me a week to calm down enough to channel my anger into an effective response (what I SHOULD have said was . . . ).

    I suggest humor. Of course, then it might take two weeks.

  8. QDP says:

    We are not being realistically factual here.
    James Hansen’s older ’05 predictions are much more dire, since there are cumulative effects in sea level rise that are NOT factored in on a global level to recent scientific approaches and calcs. (sun cycles, dust particulates, even recent GLORY mission (failure) extrapolations)
    Second, there are tipping points all across these rather bleak calculation algorithms which bring in much more accelerated timelines, from solar energy to pH balance and from Argos observed salinity- to polar current movements to methane/ozone observations and other contributors.
    What’s the worst that could happen? needs address NOW.
    There are logarithmic factor interpolations which place the timeline for much shorter. try 36 cm rise by 2036…

  9. QDP says:

    I’d guess from 2009 data GB, LOL!!

  10. QDP says:

    Exactly my fears too. We are disregarding one of the main tenets of very complex, interactive systems: All subcomponents contribute to the biosphere conditions on a cumulative basis, like the cascading effect some catastrophes bring along.
    Aren’t we supposed to be in a low 11 yr. sun cycle period right now?…. that is, shouldn’t things be much much COOLER?

  11. QDP says:

    of course we can adjust, and certainly will, but that isn’t really the point, is it?
    we all can do something now, to mitigate such sea level rise consequences, yet we are still arguing, not DOING. GCD is about the impact on global financial conditions, which we are ill-equipped to address, and changes that affect humanity on a level that gets logarithmically much more costly to reverse with every passing decade.
    See recent TEDtalks

  12. Robert In New Orleans says:

    I think future rate of sea level rise is a big unknown unknown. It seams from my prospective that the consequences of climate change are occuring much faster than were anticipated from predictions just made a few years ago.

    Thus said, what if the sea level were to rise two feet or more by 2050?

  13. Paul Magnus says:

    No it’s not really. We have ballpark range and we know that there is a high risk of ice collapse especially in west Antarctic.

  14. Paul Magnus says:

    As coastlines are encroached, will we see more GHGs from the swaps that form? Another feedback?

  15. Paul Magnus says:

    An inland flood costs and counting…

    First Nations flood evacuation costs reach $40M

  16. Robert In New Orleans says:

    Paul, I was just commenting about the difference between really fast and rising to my knees right now fast.

  17. Solar Jim says:

    Oil and money: not only will our mortgages be underwater via Wall Street fraud and bailouts but our homes and infrastructure will be underwater literally from fossil fraud.

    Maybe we should rethink this concept of matter (like petroleum fluids) as “energy resource.” What, and stop igniting what we dig up? Then we wouldn’t be fossil fools like we are. Brought to you by Gold Man Sacks, and perfectly arranged by Disaster Capitalism.