Rising Seas Could Force Millions to Relocate, Sparking Global Migration Woes
Even a global temperature increase of just 1.5°C could drive millions from coastal areas, a new study warns. The researchers say that sea levels may rise by several feet before century’s end—even at today’s warming of 1.2°C—putting coastal communities worldwide at grave risk. The findings, published in Communications Earth & Environment, suggest that catastrophic sea level rise and mass migration could occur well below previously assumed climate thresholds.
“We’re likely to witness large-scale migration unlike anything seen in modern history,” said Jonathan Bamber, study co-author and a glaciologist at the University of Bristol, in an interview with CNN.
The main driver of this projected rise is the accelerating loss of ice from Greenland and Antarctica, which has quadrupled since the 1990s and now represents the biggest contributor to global sea level rise. To forecast future changes, scientists from the U.K. and U.S. examined past warm periods dating back 3 million years, recent ice loss data, and climate modeling under different warming scenarios.
Historically, about 15,000 years ago—during the end of the last Ice Age—sea levels rose at a pace ten times faster than today. And when CO₂ levels last matched current concentrations, roughly 3 million years ago, global sea levels were between 10 and 20 meters (33 to 66 feet) higher than now.
Even if humanity rapidly cuts emissions to meet the Paris Agreement goal of limiting warming to 1.5°C, multiple meters of sea level rise still appear likely, the study finds. That target, once considered the threshold to avoid the most severe impacts, is already slipping out of reach. Alarmingly, the researchers conclude that today’s 1.2°C of warming may already commit the planet to several meters of sea level rise, suggesting the actual “safe” threshold is likely under 1°C. Determining that tipping point will require more detailed research.
Currently, we are on course for as much as 2.9°C of global warming. At that level, scientists say it’s almost certain that the Greenland and West Antarctic ice sheets will disintegrate entirely—causing sea levels to rise by up to 12 meters (around 40 feet). At present, about one billion people live within 10 meters (32 feet) of sea level, and roughly 230 million reside within just 1 meter (3 feet).
“Sea level rise is expected to speed up to levels that will be extremely hard to adapt to—rates of one centimeter per year could become the norm during the lifetimes of today’s youth,” said Chris Stokes, lead author and climate scientist at Durham University.
Last year marked the first time global temperatures briefly touched 1.5°C, though the long-term average hasn’t reached that point yet. Still, the authors emphasize that it’s not too late to act. Immediate and ambitious climate action could help minimize the damage—every inch of sea level rise avoided makes a difference.
“We’re not saying everything is lost at 1.5°C,” Stokes noted. “But every fraction of a degree is crucial for the future of the ice sheets. The sooner we stop warming, the better our chances of returning to safer levels later on.”
