New visualizations show worst-case scenario for sea levels by 2100

The U.S. Naval Academy, JFK Airport, the Jefferson Memorial and President Donald Trump's Mar-A-Lago estate all could be underwater by the year 2100.

That's the doomsday prediction of a worst-case scenario of sea levels rising out of control by the end of the century, according to the National Oceanic and Atmospheric Administration and Climate Central, a non-profit environmental research group.

NOAA's report in January included an extreme sea-level rise forecast of 10 to 12 feet of sea-level rise by 2100 around the U.S., compared to the previous estimate of about 8 feet.

Climate Central then created images that showed what such extreme water rises would look like.

In New York City, for instance, an average high tide would be 2 feet higher than Hurricane Sandy’s flood level, covering an area inhabited by more than 800,000 residents.

Florida would be the most affected state by total population, followed by New York, California, Virginia, and New Jersey. Hawaii and Louisiana would rank second and third by percentage of population affected, after Florida, also first in this category

“It’s a scenario that we hope never occurs,” said William Sweet, a NOAA oceanographer who coordinated production of the agency’s January report, “It’s probably very unlikely, but definitely possible.”

The seas have risen and fallen before. What's new is the enormity of coastal development that will need to be protected, moved or abandoned.

Sea level has risen nearly 8 inches worldwide since 1880 but, unlike water in a bathtub, it doesn't rise evenly. In the past 100 years, it has climbed about a foot or more in some U.S. cities because of ocean currents and land subsidence — 11 inches in New York and Boston, 12 in Charleston, 16 in Atlantic City, 18 in Norfolk and 25 in Galveston, Texas, according to NOAA.

Global warming blamed for record-breaking weather worldwide, scientists say

Here's why: As the Earth's temperature warms, so do the seas. Heat-trapping greenhouse gases such as carbon dioxide and methane cause more land ice (glaciers and ice sheets) to melt and water to expand. Warmer water simply takes up more room than cooler water.

Scientists say global warming will be the primary cause of future sea-level rise. Their greatest uncertainty is how quickly the massive West Antarctic ice sheet will melt.

The Antarctic ice sheet is the world’s largest reserve of frozen water, meaning its collapse would contribute more to the rise of the seas than the melting of glaciers elsewhere or the collapse of Greenland’s ice sheet, Climate Central said.

Because it’s so large, Antarctica’s ice sheet is relatively stable, although it’s already melting under the effects of rising temperatures. Scientists are trying to figure out how stable it really is, according to Climate Central.

The Fifth Assessment Report from the United Nations' Intergovernmental Panel on Climate Change, the gold-standard for climate change science that was released in 2013, said that the most likely amount of global sea level rise would be about 1 foot to slightly more than 3 feet by 2100.