Glaciers and ice sheets in western Antarctica are melting, there's nothing we can do to stop it, and the result will be a 10-foot rise in sea level within the next century or two. That's according to new reports by NASA scientists scheduled for publication in scientific journals this week, reported in advance by, well, almost every press agency on the planet.
The apparently inevitable loss of Western Antarctica's glaciers is being caused by an upwelling of relatively warm water in the Southern Ocean, driven by more intense winds around the polar continent.
There's enough water currently locked up in those glaciers that when they melt, they'll raise sea levels around the world by around 10 feet, on top of additional rise from other sources. That amount of sea level rise would change the face of California, devastating wildlife and making much of the state's vital infrastructure useless.
Sea level rise from the loss of West Antarctic glaciers is expected to proceed slowly at first, then gain steam in the early years of the next century, according to the forthcoming paper in Science by Ian Joughin, a glaciologist at the University of Washington, and colleagues.
Joughin told the New York Times that even if the melting slows, it's too late to stabilize the West Antarctic ice sheet. That ice will keep flowing into the ocean, raising sea level for at least the next 200 years.
What does this bad news mean for us here in California? Though California's relatively steep coast means much of the state will be spared direct inundation from a ten-foot rise in sea level, California would lose some of its most expensive real estate to the waves. Western San Diego would become an archipelago. The sea would penetrate well inland near Costa Mesa, Long Beach, Oxnard and Salinas. And urban northern California would be especially hard hit, with probably trillions of dollars in bayfront properties submerged.
Seas that much higher will likely eradicate what's left of one of California's most endangered wildlife habitats, coastal salt marshes and estuaries, as much as 90 percent which has already been lost. Given time, salt marshes may reestablish themselves above what had been farm fields and city streets, but that recovery is unlikely to come in time for the wildlife that depends on our present-day wetlands.
The biggest change wrought on California by a 10-foot rise in sea level will be the creation of a huge inland sea running 70 miles from downtown Sacramento to the northern outskirts of Tracy. That will displace hundreds of thousands of people, including everyone living in the western half of Stockton.
It will also sever a vital connection in the state's expensive infrastructure which we use to move water from Northern California to the farms and cities in the south: the Sacramento Delta, whose canals will be rendered unusable under several feet of saltwater.
That will mean far less water for Southern California cities and heavier demand on the Owens Valley and Colorado River aqueducts, which do not use the Delta as a ground-level connection point. It will mean an even worse forecast for those Central Valley farmers whose lands remain above water: they'll have to make do on the water in their own local rivers, which may well be less as a warming world reduces Sierra Nevada snowmelt.
And that's just the direct damage from the sea level rise itself, ignoring the effects of storm surges and upstream flooding. Aside from the expected damage even to well-elevated properties atop coastal bluffs that will soon be undercut by storms, a bad but not unusual 20-foot storm surge in the Sea of Cortez on top of a 10-foot rise in sea level could mean a catastrophic flood in Southern California that would almost certainly claim thousands of lives.
"This is really happening," said NASA polar ice researcher Thomas P. Wagner to the New York Times. "There's nothing to stop it now."
Penn State climatologist Richard B. Alley, who was not involved in the research being published this week, reminded the Times that West Antarctica's glaciers are just one contributor to sea level rise. "The heat-trapping gases could destabilize other parts of Antarctica as well as the Greenland ice sheet, causing enough sea-level rise that many of the world's coastal cities would eventually have to be abandoned," the paper noted.