We've all heard by now about how elevated levels of carbon dioxide (CO2) in the atmosphere are causing global temperatures to rise, which is melting more of the polar ice caps and causing glaciers to crack. Now, a new study from the Massachusetts Institute of Technology (MIT) says that's not the only way that carbon dioxide is harmful to the ice.
This study, lead by Professor Markus Buehler, with MIT's Laboratory for Atomistic and Molecular Mechanics, states the CO2 molecule itself causes ice to lose considerable strength by weakening the molecular bonds in the water molecules that make up the ice, making it much easier for the ice to crack and break apart.
Researchers showed this by running computer simulations of the interaction with carbon dioxide molecules with water molecules arranged in a lattice, as they would be when frozen as ice. Their simulations showed that the carbon dioxide molecules weakened the bonds between the hydrogen and oxygen atoms in the water, allowing the carbon dioxide to bond to the hydrogen instead. The carbon dioxide then migrated inward from the edge of the crack, towards the tip of the crack, by passing from one water molecule to the next. This weakening of the bonds in the water molecule significantly weakened the structure of the ice and made it far more easy for it to further crack and break apart.
The results of the paper — titled Carbon dioxide enhances fragility of ice crystals (free to read if you create an account) and published today in Journal of Physics D: Applied Physics — have not undergone any physical testing yet, but as the paper states in its conclusions: "Our theoretical model quantitatively accounts for the effect of carbon dioxide on the surface energy and fracture toughness of ice."
It is the hope of Buehler, his students and co-author Zhao Qin that their model will inspire others to design experiments to test these findings.