Climate: Heat-trapping CO2 also makes ice more brittle

New MIT research suggests carbon dioxide has direct impact on glaciers and ice caps

Cracks in the ice on Dillon Reservoir, Dec. 25, 2012. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — Have you ever poured a can of warm coke into a glass full of ice cubes and listened to the cubes crack?

Something similar might be going on in the atmosphere, as MIT researchers have shown that direct exposure to carbon dioxide makes ice caps and glaciers more susceptible to cracking.

The study is the first to show this kind of a direct impact from increasing atmospheric CO2, which as a heat-trapping greenhouse gas is directly responsible for much of the increase in global temperatures during recent decades.

The MIT study used a series of atomistic-level computer simulations to investigate the role of CO2 molecules in ice fracturing, finding that CO2 exposure causes ice to break more easily by directly affecting the hydrogen bonds between water molecules in ice crystals — because the added CO2 competes with the water molecules in the crystals.

Ice strength is also decreased by material defects induced by CO2 bubbles, according to researchers Professor Markus Buehler and Zhao Qin.

“If ice caps and glaciers were to continue to crack and break into pieces, their surface area that is exposed to air would be significantly increased, which could lead to accelerated melting and much reduced coverage area on the Earth,” said Buehler. “The consequences of these changes remain to be explored by the experts, but they might contribute to changes of the global climate,” he added.

Ice caps and glaciers cover seven per cent of the Earth—more than Europe and North America combined—and are responsible for reflecting 80 percent of the Sun’s light rays that enter our atmosphere and maintain the Earth’s temperature. They are also a natural carbon sink, capturing a large amount of CO2.

The study showed that CO2 molecules first adhere to the crack boundary of ice by forming a bond with the hydrogen atoms and then migrate through the ice in a flipping motion along the crack boundary towards the crack tip, where they accumulate and attack the water molecules by trying to bond to them. This leaves broken bonds behind and increases the brittleness of the ice on a macroscopic scale.

The research was published Oct, 11 in the Institute of Physics Journal of Physics D: Applied Physics.


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