Glacial Epoch Permafrost Carbon Pools and Fluxes: An approach combining new modeling and terrain-based reconstructions to improve knowledge of future changes


Project leader


Funding source

Swedish Research Council - Vetenskapsrådet (VR)


Project Details

Start date: 01/02/2013
End date: 31/12/2016
Funding: 2366000 SEK


Description

Glacial Epoch Permafrost Carbon Pools and Fluxes: An approach combining new modelling and terrain-based reconstructions to improve knowledge of future changes Gas bubbles trapped in the long ice cores drilled on Antarctica have shown that there has been a consistent rapid increase of about 100 ppmv CO2 in the atmosphere following the repeated glacial to interglacial transitions during the last half to one million years of Earth history. The colder and drier climate during glacial periods implied that vegetation on land was less productive and wetland extent more constrained than during warmer interglacial periods. That means that, as an average on a global scale, less carbon was sequestered by land vegetation and peat deposits in glacial compared with interglacial times. So, where did this carbon go and how to explain the reduction in atmospheric CO2 concentrations during glacial times ? Traditionally, these differences have been explained by the fact that the colder ocean during glacial times could absorb more CO2 from the atmosphere, which was subsequently released when global climate became warmer. Quite recently, particularly Russian scientists have emphasized the potential role of soil carbon stored in permafrost (ground that remains frozen over the years) as an important sink of atmospheric CO2. Recent new estimates of the present-day carbon pools in the permafrost region have drastically increased, in part because of large stocks present in the so-called yedoma deposits which are presently found mostly in northeastern Siberia. These are deposits formed during the cold and dry conditions of glacial times in a Mammoth tundra-steppe environment. These were actually quite rich soils due to the continuous fertilization by the large mammals that grazed these areas. The organic material (50% of which is carbon) was subsequently preserved by the permafrost, which largely inhibits any microbial decomposition. We know from fossil records that this Mammoth tundra-steppe environment was much more extensive during glacial times, in the non-glaciated parts of both Eurasia and North-America, and so it can be hypothesized that the permafrost carbon pool was larger than at present adding a terrestrial sink to the proposed ocean sink. The permafrost carbon pool during glacial times has, however, never been quantified in any degree of detail. That is exactly what this project aims to do by using both fossil evidence and modelling approaches to reconstruct the extent and type of permafrost landscapes and their carbon sink potential during the coldest period of the last glacial period (the Last Glacial Maximum). This will provide much better data for improved modelling of the climate system by assessing what happens to the large permafrost carbon pool as climate warms. In that way, if we better understand past transitions in the coupled climate-carbon system, we will also be able to reduce uncertainties about future global warming caused by man-made fossil fuel emissions and deforestation.

Last updated on 2017-24-03 at 12:16