Air temperatures, on the one hand, are moderated by circulation—both the rising and sinking of air masses into the atmosphere, and the horizontal movement of winds across the landscape. Moisture also regulates how much heat can be stored in the air. “The value of the air temperature measurement, as opposed to land surface temperature, is that it is what the human body, a building, or an ecosystem are feeling,” says Stuart Gaffin, a climate researcher at Columbia University and NASA’s Goddard Institute for Space Studies. “Air temperatures largely dictate our thermal comfort level.”
On the other hand, land skin temperatures reflect the pure heating of a parcel of ground by radiation from the sun, the atmosphere, and other heat flows. Therefore, the hottest LSTs are likely to occur where the skies are clear, the soil is dry, and the winds are light. The final ingredient is the composition of the land surface. It should absorb most light and reflect little—that is, have a low albedo—and it should not conduct heat very well. Rocky deserts offer the perfect combination.
“This is not the first part of East Antarctica that’s likely to show a multi-meter response to climate change,” said Alan Aitken, the new study’s lead author and a researcher with the University of Western Australia in Perth. “But it might be the biggest in the end, because it’s continually unstable as you go towards the interior of the continent.”
The research — which found that Totten Glacier, and the ice system of which it is part, has retreated many times in the past and contains several key zones of instability — was conducted in collaboration with a team of international scientists from the United States, Australia, New Zealand and the United Kingdom. A press statement about the study from the U.S. group, based at the University of Texas at Austin, described the study as showing that “vast regions of the Totten Glacier in East Antarctica are fundamentally unstable.”
Indeed, the Totten Glacier watch has been ramping up lately: Scientists have already documented that warm ocean waters can reach the glacier’s base and that the enormous ice shelf that currently stabilizes it, extending over the top of the ocean, is melting from below. The glacier is thinning quickly, and its grounding line, where the ice shelf descends and meets the seafloor, has retreated inland three kilometers between 1996 and 2013 in some areas.
Finally, recent research has suggested that Totten can only lose a tiny 4.2 percent of its remaining ice shelf before the structure starts losing the ability to brace the larger glacier, holding it in place. It all points to a region of enormous vulnerability, and one that is already undergoing change.