Report: U.S. will see 1 foot of sea level rise by 2050 because of climate change

Thanks to climate change, sea levels along the coastline of the United States will rise between 10 and 12 inches by 2050, a new interagency U.S. government report concludes.

The report, released Tuesday and written by researchers at NASA, the National Oceanic and Atmospheric Administration (NOAA) and other federal agencies, examines the impact of rising global temperatures and melting sea ice on the U.S. sea level and concludes that a certain amount of sea level rise has already been assured.

"Sea level rise driven by global climate change is a clear and present risk to the United States today and for the coming decades and centuries," the report states. "Sea levels will continue to rise due to the ocean’s sustained response to the warming that has already occurred — even if climate change mitigation succeeds in limiting surface air temperatures in the coming decades."

The cause of climate change is no longer a matter of serious scientific dispute. It is a consequence of mankind's burning of fossil fuels, the byproduct of which, greenhouse gases, trap the sun's radiation in the Earth's atmosphere, leading to warmer average temperatures. Higher temperatures are not only causing glaciers and the polar ice caps to melt, but also resulting in a process known as thermal expansion, by which the atoms in water expand, further exacerbating sea level rise.

"Global mean sea level ... rise is a direct effect of climate change, resulting from a combination of thermal expansion of warming ocean waters and the addition of water mass into the ocean, largely associated with the loss of ice from glaciers and ice sheets," the report states.

NOAA has long tracked rising sea levels. Since 1880, the oceans have risen by between 8 and 9 inches, but that rate of rise has increased in the past two decades, resulting in a 300 to 900 percent increase in high-tide flooding in the U.S. over the last 50 years. The rate will keep accelerating, the report finds.

"The trends in minor/disruptive HTF [high tide flooding] have grown from about 5 days in 2000 to 10-15 days in New York City and Norfolk, Virginia, in 2020; in Miami, Florida, and Charleston, South Carolina, annual frequencies have grown from 0-2 days to about 5-10 days over the same period," the report states. "These increases will continue, further accelerate, and spread to more locations over the next couple of decades."

A line of cars waits in line on a flooded section of a South Carolina road.
Cars wait to pass a flooded section of road in Georgetown, S.C., in 2015. (Randall Hill/Reuters)

In fact, the report concludes, "relative sea level along the contiguous U.S. coastline is expected to rise on average as much over the next 30 years as it has over the last 100 years."

By 2100, NASA predicts, climate change will cause seas to rise by 2 to 6 feet, largely because of the melting of ice in Antarctica and Greenland, but those estimates could jump sharply in the event that portions of the Antarctic ice sheet, including the Thwaites Glacier, give way to sudden collapse.

A December study based on satellite imagery of the so-called doomsday glacier found it was on the verge of collapse.

“The eastern ice shelf is likely to shatter into hundreds of icebergs,” Oregon State University glaciologist Erin Pettit said of the findings. “Suddenly, the whole thing would collapse.”

While the report notes that the amount of sea level rise over the next 30 years due to thermal expansion and glacial and ice sheet melt is already locked in, it adds that dramatically curbing greenhouse gas emissions and limiting temperature rise would avert the catastrophic inundation of U.S. coastal regions.

"If global warming reaches 2°C, corresponding to a 50% chance that U.S. sea level as a whole will rise at least 0.7m by 2100 and 1.2m by 2150, major HTF by 2100 would occur more often than minor HTF occurs today in many coastal communities if risk-reduction action is not taken," the report states. "If global mean temperatures were to rise as high as about 3°-5°C, much larger amounts of sea level rise would become increasingly possible, as instabilities in ice-sheet dynamics would potentially come into play."

In other words, the world needs to do everything it can to keep temperatures from rising much further.

“This report supports previous studies and confirms what we have long known: Sea levels are continuing to rise at an alarming rate, endangering communities around the world," NASA Administrator Bill Nelson said in a statement about the latest report, adding that "urgent action is required to mitigate a climate crisis that is well underway."