Quantifying land-surface albedo feedback using Dansgaard-Oeschger events

Land-surface shortwave albedo is an important quantity in the energy budget of the Earth. Remotely sensed snow cover, maximum tree height and maximum fractional absorbed photosynthetically active radiation (fAPAR) explain 87% of the variation in present-day annual mean land surface albedo (weighted by the seasonal cycle of shortwave radiation) in a generalized linear model. We can therefore apply this model during Dansgaard-Oeschger (D-O) warming events during the last glacial period. We have already used these repeated, rapid (50–200 year), near-global climate-change events to provide new quantifications of Earth system feedbacks involving atmospheric CO₂, CH₄ and N₂O. We now reconstruct maximum tree height and maximum fAPAR based on a new global compilation of pollen data covering the relevant time interval, combined with snow cover changes during simulated D-O events, in order to reconstruct global changes in radiative forcing due to changes in vegetation and snow cover – and thereby quantify the global land-surface albedo feedback.