File this under "Welp, this is worse than we thought." A study published in Nature Geoscience finds that warm seawater is likely getting under an East Antarctica glacier and melting it from below. If the glacier's ice shelf melts, runway melting could cause another 11 feet of sea-level rise -- that's on top of previous estimates.
Scientists have traditionally worried about the West Antarctica ice sheet, a low-lying region especially prone to runaway melting. Last year, two major studies concluded the West Antarctica ice sheet had started a slow-motion collapse, and there's nothing we can really do about it. Its melting will cause in estimated 3m rise in sea levels over the next few centuries.
This new study of the Totten Glacier in East Antarctica just adds more bad news and even more sea-level rise. After several research flights over the area, researchers were able to map out the depth of the seafloor below. Chris Mooney at the Washington Post explains what they found:
The result was the discovery of two undersea troughs or valleys beneath the ice shelf -- regions where the seafloor slopes downward, allowing a greater depth of water beneath the floating ice. These cavities or subsea valleys, the researchers suggest, may explain the glacier's retreat -- they could allow warmer deep waters to get underneath the ice shelf, accelerating its melting.
Once warm seawater erodes the ice shelf that separates glacier and ocean, seawater can pour into the low-lying area behind it, accelerating its melting, too. That's where the 3.35m additional sea level rise estimates come in.
All this goes to show how sea level rise can sneak up on us. The researchers were only able to detect the hidden troughs under the ice shelf after several flights with instruments measuring variations in Earth's gravity. Other surprises may lurk under the ice, too. Estimates are estimates, and they can be wrong in both directions, but in this particular case, it's looking like future generations are even more screwed than we once thought. [Nature Geoscience, Washington Post]
Picture: AP Photo/Natacha Pisarenko