Nearly 670 coastal areas in America could face monthly bouts of flooding by the end of this century, including more than 60 percent of communities along the East and Gulf coasts, according to a study released Wednesday by the Union of Concerned Scientists.
The analysis, published in the peer-reviewed journal Elementa, is the first to examine the threat of chronic flooding to the entire coastline of the lower 48 states. The term is used for areas where 10 percent of a community’s land is flooded at least 26 times per year, or an average of once every other week.
The report looks at three possible scenarios in the coming decades as the world works to tackle the growing threat of climate change. The “low scenario” assumes a steep decline in carbon emissions in line with the landmark Paris climate agreement, which seeks to limit global temperature increases to less than 2 degrees Celsius. The “intermediate scenario” has emissions peaking at mid-century, which would result in around 4 feet of sea level rise. And the “high scenario” assumes emissions will rise through 2100, which would spur rapid ice melt around the globe and lead to at least 6.5 feet of sea level rise.
In the middle scenario, about 170 communities would be affected by chronic flooding in less than 20 years. By 2060 that number would rise to 270, and by 2100 it would be at 490, affecting coastal communities around America. The high scenario would only make things worse in many more places, leading to the 670 figure mentioned above.
UCS released an interactive map showing the expected effects of each scenario. (The map may take a few seconds to load.)
The threats described in the study are already being felt in dozens of communities around the country, according to Erika Spanger-Siegfried, an author of the report and a senior analyst in the Climate and Energy Program at UCS.
“Some 90 communities, mostly in Louisiana and Maryland where the land is also sinking, are already facing chronic inundation from sea level rise,” Spanger-Siegfried said in a statement. “As global temperature increases sea level rise, several hundred coastal communities are looking at the same kind of chronic flooding around the middle of the century ― from beach vacation destinations like the Jersey Shore and the Gulf Coast of Florida to larger cities, including Boston, Galveston, Savannah and Fort Lauderdale. By late century, four of the five boroughs of New York City would be chronically inundated.”
Meanwhile, under President Donald Trump, the U.S. has taken steps to increase its reliance on fossil fuels and withdraw from its international climate commitments. The White House has announced a rollback of many of the previous administration’s climate policies, and Trump said last month that he would formally remove America from the Paris Agreement, which seeks to avoid the worst effects of climate change.
Sea level rise is directly linked to climate change, with the planet’s ice sheets melting at unprecedented rates due to our warming world. Surging waters threaten millions of Americans, dozens of the world’s biggest cities and an untold number of coastal assets.
Almost every other nation on the planet has vowed to dramatically reduce emissions in an effort to mitigate the threat, and every leader of the G-20 group except Trump pledged to move forward on climate change last week with or without the U.S. (although the country is the world’s second largest carbon emitter).
UCS’ report mirrors another released earlier this year by the National Oceanic and Atmospheric Administration on the final day of President Barack Obama’s presidency. That study found sea levels could rise by more than 8 feet by the end of the century ― one of the highest federal estimates ever, and more than a foot and a half higher than the UCS estimate ― if emissions are not curbed and the planet sees an “extreme” level of climate change.
An analysis by the group Climate Central found that millions of Americans in some of the country’s most populous cities would be affected under NOAA’s worst scenario, which would bring tides 2 feet higher than those seen during Hurricane Sandy to parts of New York City.
One of Trump’s flagship properties, the Mar-a-Lago club in Palm Beach, Florida, could very well be mostly underwater by 2100 due to climate change-induced sea level rise.
The president may not see sea level rise as a threat, however. In June, he told the mayor of Virginia’s Tangier Island “not to worry about” the phenomenon, according to the mayor.
UCS mentions several strategies to curb the effects of sea level rise in its report, but the study’s authors say the country has “a clear choice” ahead:
At this crossroads, reducing global warming emissions must be a national priority. The United States can still make deep cuts in heat-trapping emissions, thereby contributing to global efforts to limit climate change. We are at a turning point where we can still avoid some of the most serious human consequences and losses that our coasts ― and indeed coastal communities around the world ― face this century. We have time to respond. We must use it wisely.
Rachel Cleetus, the lead economist and climate police manager at UCS, said the best way to sidestep catastrophe would be to abide by the terms of the Paris accord. This is something the president seems unlikely to do, although other U.S. politicians have stepped up in his stead.
“Meeting the long term goals of the Paris Agreement would offer coastal communities facing chronic flooding their best chance to limit the harms of sea level rise,” Cleetus said in a statement. “Despite President Trump’s attempts to undermine near-term federal action on climate change, other countries as well as U.S. states, cities, businesses and citizens are showing firm resolve to fulfill the promise of Paris. They understand that if we fail to limit warming, we’re committing a great many people to a future of flooding and inundation, and the hard choices and significant costs that come with it.”
CORRECTION: An earlier version of this article misstated that Tangier Island was part of Maryland. It is part of Virginia.
This article originally appeared on HuffPost.