Potential net effects of climate change on High Arctic Peary caribou: Lessons from a spatially explicit simulation model

It is anticipated that climate change will have a major impact on High Arctic ecosystems. Peary caribou (Rangifer tarandus pearyi) is a caribou subspecies endemic to the Canadian High Arctic. In the past four decades, population dynamics of Peary caribou have been subject to several population die-offs due to unfavorable winter weather with ice coating on the ground or thicker-than-usual snow cover. There is general consensus that such disturbance years may increase in frequency and severity as a result of climate change. However, there is also evidence that available forage may increase due to a longer and warmer growing season. In this study we assess the net effects of climate change with a spatially explicit simulation model calibrated with data from the Bathurst Island complex (BIC) in the Canadian High Arctic. In particular, we ask under which climate change scenarios populations depart from the current conditions and either suffer or benefit from changes in the climate. The model incorporates movement of caribou groups and annual primary productivity over 100 years. Based on the model we suggest that Peary caribou may experience significantly lower population die-offs during disturbance years if biomass increases by 50% as projected within the next 100 years and if the currently estimated proportion of inaccessible caribou forage during such disturbance events does not change with climate change. However, if forage inaccessibility in poor winters increases by more than 30% over the next 100 years, caribou may experience negative net effects of climate change. This is the first comprehensive modeling study on this species and therefore of particular importance for wildlife management and local Inuit who rely on caribou as part of their culture, identity, and diet.