CO2 can crack ice

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Atomic-level simulation studies by materials science researchers Markus Buehler and Zhao Qin at the Massachusetts Institute of Technology (MIT) suggest that increased concentrations of carbon dioxide (CO2) in the atmosphere can cause ice to become more brittle, not unlike the breaking up or cracking of materials due to corrosion.

Though the work dealt with nanocrystals, their finding could have implications for much larger ice formations such as glaciers and ice caps. The result suggests that beyond the effects of global warming, the chemical composition of the atmosphere can have a direct critical effect on the movement or melting of large volumes of ice in glacial and other massive icy structures. CO2 can play the role of a corroding agent and lead to destabilisation of the structure.

According to the scientists, as in other materials, the fracture process in bulk ice such as glaciers gets initiated by single cracks propagating in ice crystals by breaking the hydrogen bonds between water molecules. These cracks will eventually grow and break down the entire glacier by propagating and branching over large distances, points out Buehler.

Simulations by Buehler and Qin showed that ice with 2 per cent CO2 was less strong and 38 per cent less tough than pure ice. In the simulations, CO2 molecules were found to attach themselves to the crack surface and move towards the crack tip, breaking the bonds between water molecules as they moved.