By Celsias Team
Posted on Sept. 3, 2010. Listed in:
While the focus of climate change has often been on ‘above surface’ activities such as burning oil, gas and coal, a new study by researchers at the University of California, Davis, examines the role the ocean plays in firstly sequestering carbon and then releasing it into the atmosphere.
To understand this process, the researches harked back to activity in the ice age by examining the chemical composition of the shells of tiny plankton fossils.
The scenario from these examinations works like this: Marine phytoplankton remove carbon dioxide from the ocean surface, grow, die and sink down into the ocean’s interior, where they are broken down into carbon dioxide by the ocean’s microbial community. The mechanism, also referred to as a “biological pump.”
Warm upper water layers form a cap on the cold, deep waters — and the carbon dioxide — somewhat akin to a bottle cap that holds the fizz in a carbonated drink. Deepwater currents move the dissolved carbon dioxide around the planet. Thousands of years pass; glaciers grow, then start to melt.
Eventually, these "old" carbon-rich waters well up to the surface and release their carbon dioxide — which of course contributes to climate change — back into the atmosphere.
While experts agree on the process, the one point of divergence in opinion is on where and how quickly the release occurs at the end of an ice age.
According to the study’s co-author Howard Spero, a UC Davis geology professor, and his colleagues, the foraminifera carbon-14 data from the study suggests that the carbon-dioxide release that preceded the current warm period on Earth was more of a big fizz than a slow leak. It lasted about 6,000 years and took place largely in the icy Southern Ocean (the waters south of 60 degrees south latitude that encircle Antarctica).
"We now understand that the Southern Ocean was the fundamental release valve that controlled the flow of carbon dioxide from the ocean to the atmosphere at the end of the last ice age. The resulting atmospheric increase in this greenhouse gas ultimately led to the warm, comfortable climate that human civilization has enjoyed for the past 10,000 years," Spero concludes.
Image: Flickr - missmariejasmine
