The Antarctic Ocean Today Looks a Lot Like It Did 14,000 Years Ago—When Sea Levels Suddenly Rose 13 Feet
The currents surrounding Antarctica appear to be reverting to an old pattern—14,000 years old—and that doesn’t bode well for the future.
We could be in for an abrupt 10-foot to 13-foot rise in global sea levels if history repeats itself. Research published in the Nature Communications Journal this week showed today’s water temperatures around the Antarctic are closely mimicking those of 14,000 years ago—the last time the earth warmed out of an ice age.
Using ice sheet and climate models to re-create Antarctica’s historic ice levels, the team, led by scientists from Victoria University of Wellington in New Zealand, found that when ocean temperatures become layered, or stratified, with warmer waters below colder water. When that happens, the ice sheet melts faster than when water temperatures are more evenly mixed.
“At the surface the water is getting colder and less salty, with more extensive sea ice occurring in some areas,” said Nick Golledge, a senior research fellow at Victoria’s Antarctic Research Center. “But the deeper ocean is warming and is already accelerating the decline of glaciers such as Pine Island and Totten.”
Study coauthor Matthew England said that land-based ice on the continent continues to melt, adding massive amounts of freshwater to the ocean surface.
That excess of cold freshwater on the surface has contributed to increases in the amount of sea ice around Antarctica, which has expanded farther this season than ever before.
“It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet,” England said in a statement.
What does it mean for sea levels?
The last time similar layering of Antarctic Ocean temperatures occurred, the ensuing melt-off brought a 10- to 13-foot increase in global sea levels.
If that were to occur today, about 10 percent of the world’s population would be underwater. Golledge said declines in the Pine Island Glacier—about two-thirds the size of the United Kingdom—could be just the start.
Pine Island Glacier is in West Antarctica; recent studies have shown that the region as a whole is contributing about one-third of one millimeter per year to sea level rise.
While that may not seem like much, climate change is taking out huge chunks of glacier ice worldwide, with about 300 billion tons lost between Antarctica and Greenland annually. The melting process could accelerate in years to come.
“The big question is whether the ice sheet will react to these changing ocean conditions as rapidly as it did 14,000 years ago,” said Golledge. “With 10 percent of the world’s population, or 700 million people, living less than 10 meters above present sea level, an additional three meters of sea level rise from the Antarctic alone will have a profound impact on us all.”