METHANE AND CARBON DIOXIDE FLUX CHANGES DURING OXYGEN ISOTOPE STAGE 3 IN THE NORTHWEST EUROPEAN LOWLANDS

During Oxygen Isotope Stage 3 the northwest European lowlands were situated within the periglacial zone, and marshy alluvial plains were an important part of the landscape. Sedimentation rate generally has been high in the river valleys, and the resulting fluvial deposits usually contain abundant peaty and humic silt beds. The rapid climatic fluctuations during O.I. Stage 3 may have had a strong influence on the carbon cycle of these extensive wetlands.

Sequestration of carbon dioxide in peat did not vary strongly with climate change. There is no clear evidence of large scale changes in vegetation. Also the sedimentary record does not show clear fluctuations of the amount of carbon stored in the deposits, e.g. by intensification of organic matter deposition during interstadials.

However, methane fluxes from wetlands are highly sensitive to temperature. Climate model output of the Stage 3 climate, derived from the "Stage 3 project" has been used as input to a wetland carbon flux model (PEATLAND). This resulted in differences between 'interstadial' and 'stadial' methane flux up to 50% in extreme cases. These differences are largely due to the differences in temperature, in combination with slightly higher primary productivity. The periglacial wetland ecosystems of northwest Europe and similar regions in Eurasia contributed to the atmospheric methane variations of the last glacial, and their methane fluxes may have reacted rapidly to temperature change.