The Potential Role of Peatland Dynamics in Ice-Age Initiation

Physical and chemical coupling of peatland vegetation, soils and landforms, and atmosphere creates feedbacks which may be important in ice-age initiation. A box diffusion CO₂ exchange model shows that a transient forcing of 500 Gt C (the amount proposed to have accumulated in peatlands during the last interglacial-glacial transition) over 5000 yr results in a lowering of atmospheric CO₂ by about 40 ppm. Proxy data indicate that a decrease in atmospheric CO₂ may have occurred over the last 5000 yr up to preindustrial times, and the amount is similar to that calculated from Holocene peatland expansion (∼22 ppm). These results suggest that models should consider the role of peat-lands in ice-age initiation.