Ah, here's the original article:
Science 16 June 2006:
Vol. 312. no. 5780, pp. 1612 - 1613
Permafrost and the Global Carbon BudgetSergey A. Zimov1, Edward A. G. Schuur2, F. Stuart Chapin III3
The carbon content of Earth's atmosphere has increased from ~360 gigatons (Gt)--mainly as CO2--during the last glacial maximum to ~560 Gt during preindustrial times and ~730 Gt today. These changes reflect redistributions among the main global carbon reservoirs. The largest such reservoir is the ocean (40,000 Gt, of which 2500 Gt is organic carbon), followed by soils (1500 Gt) and vegetation (650 Gt). There is also a large geological reservoir, from which ~6.5 Gt of carbon are released annually to the atmosphere by burning fossil fuels.
Permafrost (permanently frozen ground) is an additional large carbon reservoir that is rarely incorporated into analyses of changes in global carbon reservoirs. Here we illustrate the importance of permafrost carbon in the global carbon budget by describing the past and potential future dynamics of frozen loess (windblown dust, termed yedoma in Siberia) that was deposited during the glacial age, covering more than 1 million km2 of the north plains of Siberia and Central Alaska to an average depth of ~25 m.
The frozen yedoma represents relict soils of the mammoth steppe-tundra ecosystem that occupied this territory during glacial times (1). ...we estimate the carbon reservoir in frozen yedoma to be ~500 Gt (2). Another ~400 Gt of carbon are contained in nonyedoma permafrost (excluding peatlands) (3), and 50 to 70 Gt reside in the peatbogs of western Siberia (4). These preliminary estimates indicate that permafrost is a large carbon reservoir, intermediate in size between those of vegetation and soils....
In response to climate warming, permafrost sediments have already begun to thaw (6), with extreme projections that almost all yedoma will thaw by the end of the 21st century (7).
In other extinct megafauna news, disgraced stem-cell researcher Hwang Woo-suk apparently was fraudulently channeling research money into an attempt to clone a mammoth.