Can arctic mammals adapt to global warming?

Global warming is dramatically changing arctic marine ecosystems. As global temperatures increase, glaciers are melting and sea levels are rising. These environmental changes threaten arctic mammals, such as polar bears, who rely on sea ice for resting, walking, stalking, and nursing. With the rapid decline in the amount and thickness of arctic ice, polar bears, along with other arctic mammals, must adapt or perish. In their article, Moore et al. predict how effectively arctic mammals will adapt to the rapid environmental changes by comparing levels of “resiliency”. They examined 11 different species that rely on arctic ecosystems and based their predictions on simple parameters such as population size, behaviour, and health.

The researchers categorized the 11 species they examined into two groups; winners and losers. The ‘winners’ included cetaceans, such as the bowhead whale, beluga, and grey whale, that migrate to arctic waters seasonally. From recent observations, it appears that the ‘winners’ group is increasing in population size, calf count, and body condition. By contrast, the ‘losers’ are mammals that rely on sea ice like polar bears, walruses and ringed seals. The researchers observed that this group have to swim farther to feed and are becoming isolated from major populations.

Following initial characterization of these groups of mammals, the researchers next studied resiliency to the changing environment. Greater resilience is associated with larger populations that display behavior flexibility (including diet) and are relatively resistant to disease. Resiliency was ranked on a five-point scale; one being very resilient and five being susceptible. On this scale, bowhead whales scored at one, whereas polar bears scored at four. The overall goal of this research was to provide a data-driven assessment of mammal resiliency to climate change in the arctic, which could inform public policy.