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 CCCMACGCM3.1).
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). Overall, increases in C storage in the vegetation and soils across the study region would act
as a negative feedback to climate. By exploring these feedbacks to climate, we can reach a more
integrated understanding of the manner in which climate change may impact interactions between
high-latitude ecosystems and the global climate system.
