Carbon cycling in the terrestrial biosphere was much smaller during last ice age than in today’s cl…

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http://www.bristol.ac.uk/news/2011/8055.html

Carbon cycling in the terrestrial biosphere was much smaller during last ice age than in today’s climate

Press release issued 20 November 2011

A reconstruction of plants’ productivity and the amount of carbon stored in the ocean and terrestrial biosphere at the last ice age is published today in Nature Geoscience. The research by an international team of scientists greatly increases our understanding of natural carbon cycle dynamics.

Atmospheric carbon dioxide (CO2) is one of the most important greenhouse gases and the increase of its abundance in the atmosphere by fossil fuel burning is the main cause of future global warming. In past times, during the transition between an ice age and a warm period, atmospheric CO2 concentrations changed by some 100 parts per million (ppm) – from an ice age value of 180 ppm to about 280 ppm during warm periods.

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From these results, the authors conclude that the cycling of carbon in the terrestrial biosphere – that is, the time between uptake by photosynthesis and release by decomposition of dead plant material – must have been much smaller than in the current, warmer climate. Furthermore there must have been a much larger size of non-decomposable carbon on land during the Last Glacial Maximum (the period in the Earth’s history when ice sheets were at their maximum extension, between 26,500 and 19,000 years ago).

The authors suggest that this inert carbon should have been buried in the permanently frozen soils and large amounts of peat of the northern tundra regions.

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http://dx.doi.org/10.1038/ngeo1324