Consequences of changes in vegetation and snow cover for climate feedbacks in Alaska and northwest Canada

• Published in: Environmental Research Letters
• Main Authors: E S Euskirchen, A P Bennett, A L Breen, H Genet, M A Lindgren, T A Kurkowski, A D McGuire, T S Rupp
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2016
• Subjects: atmospheric heating; snow cover duration; shrubification; treeline advance; boreal forest fire; tundra fire; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999; Arctic; Canada; Pacific; albedo; permafrost; Tundra; Alaska
• Online Access: https://doi.org/10.1088/1748-9326/11/10/105003; https://doaj.org/article/8e776b24dedc4ae2b161ed72108de98e

Changes in vegetation and snow cover may lead to feedbacks to climate through changes in surface albedo and energy fluxes between the land and atmosphere. In addition to these biogeophysical feedbacks, biogeochemical feedbacks associated with changes in carbon (C) storage in the vegetation and soils may also influence climate. Here, using a transient biogeographic model (ALFRESCO) and an ecosystem model (DOS-TEM), we quantified the biogeophysical feedbacks due to changes in vegetation and snow cover across continuous permafrost to non-permafrost ecosystems in Alaska and northwest Canada. We also computed the changes in carbon storage in this region to provide a general assessment of the direction of the biogeochemical feedback. We considered four ecoregions, or Landscape Conservations Cooperatives (LCCs; including the Arctic, North Pacific, Western Alaska, and Northwest Boreal). We examined the 90 year period from 2010 to 2099 using one future emission scenario (A1B), under outputs from two general circulation models (MPI-ECHAM5 and CCCMA-CGCM3.1). We found that changes in snow cover duration, including both the timing of snowmelt in the spring and snow return in the fall, provided the dominant positive biogeophysical feedback to climate across all LCCs, and was greater for the ECHAM (+3.1 W m ^−2 decade ^−1 regionally) compared to the CCCMA (+1.3 W m ^−2 decade ^−1 regionally) scenario due to an increase in loss of snow cover in the ECHAM scenario. The greatest overall negative feedback to climate from changes in vegetation cover was due to fire in spruce forests in the Northwest Boreal LCC and fire in shrub tundra in the Western LCC (−0.2 to −0.3 W m ^−2 decade ^−1 ). With the larger positive feedbacks associated with reductions in snow cover compared to the smaller negative feedbacks associated with shifts in vegetation, the feedback to climate warming was positive (total feedback of +2.7 W m ^−2 decade regionally in the ECHAM scenario compared to +0.76 W m ^−2 decade regionally in the CCCMA scenario). ...