McClintock: Discovery of Warm Water Under Glacier Bodes Ill for Sea Level Rise

Thwaites Glacier. (Source: NASA/OIB/Jeremy Harbeck)

News of warmer water under a huge western Antarctic glacier should catch the attention of folks along coastal Alabama, a UAB polar scientist said this week.

Last week scientists announced that sea water under the Florida-sized Thwaites Glacier is 3.6 degrees Fahrenheit warmer than expected. That’s a finding that UAB polar scientist James B. McClintock expects will push expected sea level rise toward the upper range of the 0.9 to 3.6 feet predicted last year by the United Nations International Panel on Climate Change.

“This is something we care about in Alabama, because it’s going to increase the calculations for sea level rise on the Gulf Coast. It’s going to be important to you if you’re living in especially low-lying areas like Bayou la Batre or the western side of Dauphin Island, for example,” McClintock said.

McClintock, a UAB Endowed University Professor of Polar and Marine Biology, speaks frequently about climate change. He is scheduled to deliver talks on Thursday to the Cahaba River Society annual meeting and on Saturday to a community dialogue of the Citizens’ Climate Education-Birmingham. Since 1989, he has led 15 research expeditions to Antarctica. For the past year, McClintock has served as a spokesperson on the changing climate for the Alabama chapter of The Nature Conservancy.

The researcher, author and explorer said the warming water under the Thwaites Glacier is due to rising atmospheric temperatures. The increase in air temperature is transferred to the world’s oceans. The Thwaites Glacier is on the western portion of the continent, where the Antarctic circumpolar current becomes shallower, and this may be playing a role in warming the deep underside of the glacier.

Melting ice from glaciers accounts for about half of the sea level rise that threatens the world’s coasts, while the other half comes from expansion of the oceans’ water molecules as temperatures rise, McClintock said.

The Thwaites Glacier acts as a kind of cork, or barrier, to keep the ice sheet on top of the western portion of the continent, slowing its flow toward the sea, he said.

“If you pull out the cork, the anticipated rate of movement of the ice off of the continent and into the ocean is accelerated. The news that water is warming underneath is a big deal,” he warned.

Scientists drilled more than 2,000 feet through the Thwaites Glacier to measure the water temperature at the grounding line, where it begins extending out into the sea from land. Their expedition was part of the International Thwaites Glacier Collaboration.

McClintock said the Thwaites Glacier finding surprised polar scientists, who expected to discover underlying temperatures at about 29 degrees F; salt in seawater lowers its freezing point. While he doesn’t think the entire glacier will melt by the end of this century, if it continues to disappear from increasing temperatures under it, as well as from the warming of the atmosphere, “scientists estimate the resultant overall effect on sea level could be up in the three-foot range,” he said.

And don’t forget, he said, while Thwaites may be the largest and most important glacier in Antarctica, it’s not the only one there. “Its faster melting rate is an indication of what other glaciers are also experiencing as the deep Antarctic circumpolar current is warming,” he said.