Future Biome Projections in Alaska and East Russia

Abstract:

We projected Arctic biomes across a region including Alaska and Eastern Russia using the BIOME4 biogeochemical and biogeography vegetation model. BIOME4, which produces an equilibrium vegetation distribution under a given climate condition, was forced by CMIP5/PMIP3 climate data considered in IPCC AR5. We are exploring vegetation and permafrost distributions during the last 21,000 years and future projections (2100 C.E.) to gain an understanding of the effects of climate shifts on this complex subsystem. When forced with the baseline climatology, compiled from the University of Delaware temperature and precipitation climatology and ERA-40 sunshine data, our biome simulations were generally consistent with current vegetation observations in the study region. The biomes in this region are mostly evergreen and deciduous taiga capped by shrub and graminoid tundras to the north. The more noticeable differences were the tree line simulated north of the Brooks Range in Alaska and evergreen taiga in southwest Alaska where we know these biomes do not exist today.

The projected changes in climate conditions in the region under a RCP8.5 climate scenario (significant warming upwards of 10°C by some models, an increase in precipitation by as much as 40%, and carbon dioxide concentration reaching approximately 940 ppm) drive shifts in Arctic biomes. The tree line shifts northward while shrub tundra and graminoid tundra regions decrease significantly. An intrusion of cool mixed, deciduous, and conifer forests above 60° north, especially in southwest Alaska, were marked and were not modeled for present day. Across eastern Russia, deciduous taiga begins to overtake evergreen taiga, except along the coastal regions where evergreen taiga remains the favored biome. The implications of vegetation shifts in the Arctic are vast and include effects on snow cover, soil properties, permafrost distribution, and albedo, not to mention impacts on local fauna and people of the Artic.