Sea levels along United States coastlines will rise as much as one foot by 2050, according to a new report led by the National Oceanic and Atmospheric Administration (NOAA). Given how quickly the planet is warming due to human-caused climate change, scientists anticipate water will rise two feet by the end of the century.
“The United States is expected to experience as much sea level rise in the next 30 years as we saw over the span of the last century,” says Rick Spinrad, the NOAA administrator, at a news conference announcing the findings. “What we’re reporting out is historic.”
The report presents an alarming scenario for the roughly 127 million Americans that live in coastal counties. Flooding is expected to become more frequent and more damaging, and storm surges more intense. Sea level rise will also damage sensitive wetland ecosystems and increase erosion. By 2050, scientists expect moderate flooding to occur near coasts, on average, more than ten times as often as it does today.
“We’re unfortunately headed for a flood regime shift,” William Sweet, an oceanographer at NOAA tells Sarah Kaplan and Brady Dennis of the Washington Post. “There will be water in the streets unless action is taken in more and more communities.”
There are two primary causes of global sea-level rise: thermal expansion caused by warming waters and increased melting of land-based ice like glaciers and ice sheets.
The work in the report builds on a similar 2017 study of sea level rise but offers more precise estimations thanks to improved computer modeling and information on ice melt, Henry Fountain reports for the New York Times. In their analysis, scientists pulled information from tidal gauges and satellite images, and considered the latest predictions from the United Nations report on climate change. Their work revealed that sea level along the coastlines is projected to rise, on average, 10 to 12 inches in the next 30 years and up to two feet by 2100. The East and Gulf coasts are expected to see water rise the fastest due to land subsidence and compacting sediments, according to the report. The study gives decade-by-decade projections for sea level rise for all U.S. states and territories over the next 100 years.
Because of the amount of planet-warming greenhouse gasses humans have already emitted by fossil fuels, some future sea level rise is unavoidable. The ocean has taken the brunt of carbon emissions, absorbing and storing more than 90 percent of the excess heat added linked to greenhouse gas emissions.
Despite the damage that’s already been done, scientists behind the report say curbing greenhouse gas emissions could still reduce the severity of sea level rise projections for 2100, according to CNN’s Rachel Ramirez. But if emissions aren’t cut, coastal communities could see an extra foot and a half to five feet more to sea levels by the end of the century, for a total of up to seven feet, the analysis concluded.
"This report is a wake-up call for the US, but it's a wake-up call with a silver lining," said Spinrad at the news conference. "It provides us with information needed to act now to best position ourselves for the future."