The potential peatland extent and carbon sink in Sweden, as related to the Peatland / Ice Age Hypothesis

Peatlands cover approximately 65,600 km2 (16 %) of the Swedish land area. The available areas suitable for peatland expansion are far from occupied after ca. 12,000 years of the present interglacial. We estimate the potential extent of peatland in Sweden, based on slope properties of possible areas excluding lakes and glaciofluvial deposits. We assume no human presence or anthropic effects, so the calculation is speculative. It may have been relevant for previous interglacials.We calculate the potential final area of peatlands in three scenarios where they cover all available land with different maximum slope angles (1 3 o) using a Digital Elevation Model (DEM). The three scenarios yield potential peatland areas of 95,663 km2 (21 % of total available area), 168,287 km2 (38 %) and 222,141 km2 (50 %). The relative increases from the present 65,600 km2 are 46, 157 and 239 % respectively.The slope scenarios give CO2 uptake rates of 8.9 10.8, 18.1 22.4 and 24.6 30.5 Mt yr 1. Under global warming conditions with isotherms moved northwards and to higher altitudes, following an increase of raised bog area, the CO2 uptake rates might increase to 12.2 13.8, 24.4 27.7 and 33.5 37.9 Mt yr 1; i.e. up to 4.3 4.9 vpb of atmospheric CO2. If we make the speculative extrapolation from Sweden to all high latitude peatlands, and assume that all suitable areas with slope angle ≤ 3 ° become occupied, the global peatland CO2 sink might approach 3.7 Gt yr 1 (about 2 vpm yr 1) and potentially cause a net radiative cooling approaching 5 W m 2.