CO2 and Where it Hid in the Last Ice Age
Climate theory has it that as atmospheric CO2 concentrations go up it gets warmer and vice versa. So where does it goes when it is not in the atmosphere? Much of the CO2 was hidden in the ocean, which explains its low atmosphere concentration during the last Ice Age 20,000 years ago, a group of researchers have just said. Climate researchers from the Universities of Bern (Switzerland) and Grenoble (France) and the Alfred Wegener Institute for Polar and Marine Research (Germany) found this close connection between CO2 and temperature has existed over the past 800,000 years.
"We have now been able to identify processes in the ocean which are connected to the observed rise in CO2," said Jochen Schmitt, from Oeschger Centre for Climate Change Research, University of Bern, who led the study, the journal Science reported.
There are only a few places where the CO2 can hide. One is the ocean, Another would be as biomass or in geologic formations such as in limestone. A variation of the ocean storage space is whether the CO2 goes into the deep ocean or into the upper ocean.
According to Schmitt, during the Ice Age more and more CO2 accumulated in the deep ocean, causing the concentration of atmospheric CO2 to drop, said a university statement.
Only at the end of the Ice Age was this stored CO2 transported back to the sea surface through changing ocean circulation and thus emitted back into the atmosphere, the researchers wrote.
A new method for isotope measurements has now made it possible for the first time "to reliably decode the fingerprint of the CO2 preserved in the ice," explained Schmitt.
Oceans are at present CO2 sinks, and represent the largest active carbon sink on Earth, absorbing more than a quarter of the carbon dioxide that humans put into the air. On longer timescales they may be both sources and sinks - during ice ages CO2 levels decrease to ~180 ppmv, and much of this is believed to be stored in the oceans. A small fraction of the organic carbon transported by the biological pump to the seafloor is buried in anoxic conditions under sediments and ultimately forms fossil fuels such as oil and natural gas.
For further information: http://www.sciencemag.org/content/early/2012/03/28/science.1217161