How Carbon Saved Earth from Becoming a Big Snowball
Image courtesy of dsearis
With all the sobering talk of rising greenhouse gas emissions and ocean acidification, it seems hard sometimes to recall that "greenhouse" and "carbon dioxide" weren't always so firmly wedded to the issue of global warming. Indeed, were it not for the greenhouse effect - through which carbon dioxide and other GHGs capture and trap the sun's heat in the atmosphere - life would not have flourished on Earth as it has.
New geological data has shown that Earth came perilously close to being permanently plunged into subfreezing conditions several hundred million years ago - a shift in the planet's climate that was only averted through the presence of carbon. This has lent credence to the so-called the "snowball Earth hypothesis," which alleges that the planet required millions of years to fully recover from such freezes - and that it did so with the help of atmospheric carbon dioxide originating from volcanic eruptions.The University of Toronto team, led by W. Richard Peltier, discovered that carbonates in the sea bottom helped prevent the freezing conditions from overtaking the entire planet - creating a "slushball Earth". Diminishing global temperatures facilitated the oceans' uptake of oxygen; the excess gas then reacted with carbonates, releasing carbon dioxide back to the atmosphere - spurring a bounceback in global temperatures.
This helped stabilize climactic conditions - preventing the planet from entering a permanent frozen phase. According to Alan Jay Kaufman, a geologist at the University of Maryland, it is these feedback systems that should theoretically prevent the planet from undergoing a period of disproportionate global warming. However, because this stabilization process normally takes place over several thousand years, Kaufman notes it will likely have no impact during our lifespans.
Via ::ScienceNOW: Did Carbon Save Earth From a Deep Freeze? (news website)