Rising Seas Could Displace Millions, Triggering Global Migration Crisis, Study Warns

Sea level rise will force millions of people to flee coastal regions, even at just 1.5 degrees Celsius of global heating, according to a new study. The authors of the study warn that even current warming levels could lead to multiple feet of sea level rise by the end of the century, posing dire consequences for coast-dwellers.

The study, published in the journal Communications Earth and Environment, suggests that even at 1.2 degrees C above the pre-industrial average—our current average level of warming—could lead to catastrophic sea level rise and mass migration.

If current trends persist, “You’re going to see massive land migration on scales that we’ve never witnessed since modern civilization,” Jonathan Bamber, study co-author and glaciologist at the University of Bristol, told CNN.

Seas will rise due to the rapid loss of ice sheets from Greenland and Antarctica, which has quadrupled since the 1990s and is now the biggest source of sea level rise.

In the study, a team of scientists from the U.K. and the U.S. used evidence from warm periods up to 3 million years ago, recent trends in ice loss, and climate models to predict future ice sheet change under several climate scenarios.

Looking back, they found that about 15,000 years ago, at the end of the last Ice Age, the rate of sea level rise was 10-fold greater than it is today. The last time carbon dioxide levels in the atmosphere were as high as today, about 3 million years ago, the sea level was 33 to 66 feet (10 to 20 meters) above where it is now.

Multiple meters of sea level rise are in our future even if we rapidly and drastically cut back on fossil fuels to hit the Paris Agreement goal of 1.5 degrees C of warming above the pre-industrial average, the authors found. That target, which was thought to be the best way to prevent the worst impacts of climate change, has almost slipped away. Alarmingly, the new study finds that 1.2 degrees C would generate several meters of sea level rise.

The safe limit, the authors found, is likely below 1 degree C. The researchers said that more research is needed to determine the actual tipping point.

We’re currently on track for up to 2.9 degrees Celsius of global heating, at which point it’s pretty much a certainty that ice sheets in Greenland and west Antarctica will completely collapse. The melting of those ice sheets would cause 40 feet (12 meters) of sea level rise. Currently, one billion people live within 32 feet of sea level and around 230 million people live within 3 feet of sea level.

“People need to be aware that sea level rise is likely to accelerate to rates that are very difficult to adapt to—rates of one centimeter per year are not out of the question within the lifetime of our young people,” Chris Stokes, a climate scientist at Durham University and lead author of the study, said in a statement.

The average global temperature hit 1.5 degrees C for the first time last year, although it hasn’t quite hit the 1.5 degrees C average yet. There’s still time to do something about all of this, though. The authors urge immediate, urgent climate action to slow the worst impacts of sea level rise—every inch counts.

“We are not necessarily saying that all is lost at 1.5 degrees C, but we are saying that every fraction of a degree really matters for the ice sheets—and the sooner we can halt the warming the better, because this makes it far easier to return to safer levels further down the line,” Stokes said in a statement.