Rising atmospheric carbon dioxide actually cools part of Antarctica

NASA

Rising atmospheric carbon dioxide actually cools part of Antarctica

In a world where most regions are warming because of increasing concentrations of atmospheric carbon dioxide (CO2), central Antarctica has been cooling slightly in recent years. Greenhouse gases such as CO2 typically trap heat radiated back toward space from the planet’s surface, but large swaths of the East Antarctic Ice Sheet (the broad pink mass on the right side of the image) are, on average, actually colder than the upper layers of the atmosphere for much of the year—the only place on Earth where that’s true. When the team looked at the overall balance between the radiation upward from the surface of the ice sheet and the radiation both upward and downward from the upper levels of the atmosphere across all infrared wavelengths over the course of a year, they found that in central Antarctica the surface and lower atmosphere, against expectation, actually lose more energy to space if the air contains greenhouse gases, the researchers report online and in a forthcoming Geophysical Research Letters. And adding more CO2 to the atmosphere in the short-term triggered even more energy loss from the surface and lower atmosphere there, the team’s climate simulations suggest. The topsy-turvy temperature trend stems, in part, from the region’s high elevation; much of the surface of the ice sheet smothering East Antarctica lies above an elevation of 3000 meters, so it is much colder than it would be at lower altitudes. Moreover, that region often experiences what meteorologists call a temperature inversion, where temperatures in the lowest levels of the atmosphere are cooler than those higher up. For the lower-altitude fringes of the icy continent, and for the rest of the world (even Siberia and Greenland), the greenhouse effect still works as expected.