October 11, 2012
Researchers Show Glaciers Are Cracking In The Presence Of Carbon Dioxide
Alan McStravick for redOrbit.com — Your Universe Online
Our glaciers and ice caps are experiencing a little chemistry-based “good cop, bad cop” and it looks like the bad cop is going to make them crack under pressure.
There is little doubt in the scientific community about the excessive presence at startling levels of carbon dioxide (CO2) in our atmosphere and the effect it is having on our increasing global temperatures and our melting ice caps and glaciers.
Researchers from the Massachusetts Institute of Technology (MIT) wanted to explore the relationship between CO2 and our global refrigerator on a molecular level. Their study, printed today in the Institute of Physics (IOP) Publishing´s Journal of Physics D: Applied Physics, has shown that CO2 molecules may be having a much more direct impact on the ice caps and glaciers than was previously believed.
Specific to the cracking, and breaking up of glaciers and the ice cap, the team learned that the material strength and fracture toughness of ice are severely decreased under increasing concentrations of the CO2 molecule. These higher levels of CO2 make ice caps and glaciers more vulnerable to cracking and splitting into pieces. They believe their results help to explain how the huge crack that had been seen in the Pine Island Glacier in Antarctica eventually gave way, creating a new glacier that is roughly the size of Berlin.
With overall coverage that dwarfs Europe and North America combined, our ice caps and glaciers cover 7 percent of the Globe. They are instrumental in the reflection of 80 percent of the Sun´s light rays that enter our atmosphere, helping to maintain the Earth´s temperature. Unfortunately, they are a natural carbon sink that captures a large amount of CO2.
"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. The consequences of these changes remain to be explored by the experts, but they might contribute to changes of the global climate," said lead author of the study Professor Markus Buehler.
Professor Buehler, working with his student and co-author, Zhao Qin, employed a series of atomistic-level computer simulations in order to analyze the dynamics of molecules so as to investigate the role of CO2 molecules in ice fracturing. Their results showed CO2 exposure does, in fact, cause ice to break more easily.
What Buehler and Qin found was the decreased ice strength is not due to material defects in the ice caused simply by CO2 presence, but instead by the fact that the strength of the hydrogen bonds are, themselves, weakened under the increasing concentrations of CO2. Hydrogen bonds are the chemical bonds between water molecules in an ice crystal. The CO2 actually competes with the water molecules connected in the ice crystal.
They were able to show how the CO2 molecules will first adhere to a crack boundary in the ice by forming a bond with the hydrogen atoms. That bond will then travel through the ice, in a flipping motion, along the crack boundary until it reaches the crack tip.
Once the CO2 molecules accumulate at the crack tip they begin a constant barrage on the water molecules in their attempt to bond with them. This process leaves a trail of broken bonds in its wake all the while increasing the brittleness of the ice on a macroscopic scale. And that´s how a bad cop gets his perp to crack. Case closed.