Multimodel Future Projections of the Regional Vegetation‐Climate System Over East Asia: Comparison Between Two Ensemble Approaches
Weiguang Liu, Guiling Wang, Miao Yu, Haishan Chen, Yelin Jiang
Abstract
Abstract This study compares two ensemble methods, pseudo global warming (PGW) and multimodel ensemble (MME) mean in evaluating future vegetation‐climate changes and feedback over East Asia using a regional model driven with boundary conditions derived from historical and RCP8.5 runs of four global models. Over most of the domain, MME and PGW produce similar future climate changes, except for two regions: over Northeast Asia, MME projects less winter warming and less increase of summer precipitation than PGW, and over North China Plain, MME projects greater increase of summer precipitation than PGW. Both PGW and MME project greater leaf area index (LAI) and expansion of tree coverage at the expense of grass over most of the domain due to elevated CO 2 concentration and climate change. However, over Northeast China, PGW and three ensemble members project an increase of temperate trees at the expense of boreal trees or grass and a decrease of LAI, and one ensemble member projects a loss of forest to grassland. Both PGW and MME identify two hotspots of vegetation‐temperature feedback, including the Northeast China where the projected loss of boreal evergreen forest causes a significant winter cooling (which offsets a major portion of greenhouse gas‐induced warming) and the Tibetan Plateau where the projected LAI increase and vegetation expansion lead to a significant winter warming through reduced albedo. The vegetation feedback impact on precipitation is similar between the two approaches, including a significant wet signal in a belt between 30°N and 40°N during winter and over the Tibetan Plateau during summer.