Credit: Viacheslav Misiurin
The progressive decline in Arctic sea ice will allow for greater opportunities for industrial development, commerce, and recreation. Increases in human activities in the Arctic are likely to result in environmental risks to polar bears, including fragmentation of and displacement from critical habitats, exposures to oil, and increased likelihood of human-polar bear conflict. Understanding and mitigating these risks will be a challenge in the coming decade.
The global demand for oil and natural gas is expected to grow by about 27% and 38%, respectively, over the next two decades. Geologically-based assessments suggest that the area north of the Arctic Circle may contain 13% of the world’s undiscovered oil and 30% of the world’s undiscovered gas, much of which is believed to occur in areas occupied by polar bears. Oil and gas development poses a wide range of threats to polar bears, from exposure to oil from accidental spills to displacement from maternity dens.
An oil spill in sea ice habitat will likely result in the accumulation of oil in leads and between ice floes, features favored by polar bears and their main prey (ringed and bearded seals). Polar bears could be exposed to oil from ingesting oiled seals or by swimming through fouled water. Studies have shown that polar bear fur is capable of absorbing large quantities of oil. Following exposure, polar bears groom themselves and risk ingesting sufficient oil to result in kidney failure, digestive system disorder, and brain damage that ultimately results in death. Other effects include loss of insulation from fur, focal hair loss, and skin and eye irritations.
The full extent of minor and chronic exposures of polar bears to oil is unclear. The general consensus is that a polar bear population exposed to an oil spill could suffer mortality sufficient to reduce the population, with the magnitude of the reduction dependent upon the time of year, sea ice conditions, and the area and volume of the spill. Given the relatively low population growth rates of polar bears, a population affected by an oil spill may take many years to recover.
Another concern from oil and gas development relates to exploration methods such as seismic surveys. Studies suggest that polar bears are sensitive to disturbance at maternity den sites. Industrial activities in the Arctic typically reach peak intensities in the winter, which spans the time bears are entering and eventually exiting maternity dens. Disturbances from sounds and vibrations could occur when a pregnant female is selecting a den site and during the winter-spring after the cubs are born. If exploration or development occurred sufficiently close to a den, the mother may abandon the den prematurely or abandon her offspring. It is thought that with careful planning and control of exploration activities, the risk of disturbing denning bears can be reduced.
Additional effects associated with industrial development include increased ship traffic, pollution from chemical compounds used in drilling operations, and noise. The responses of polar bears to these effects are mostly unknown. Ice-breaking vessels may have negative impacts on the breeding habitat of ringed seals but these effects are likely to be fairly localized. Trans-Arctic shipping volume is projected to increase as sea ice cover continues to decline, and the increased shipping activity may pose a strike risk to polar bears traversing open water. Polar bears may be poisoned by ingesting chemical compounds found at industrial sites, though such incidents appear to be rare. Noise associated with industrial operations may cause polar bears to displace from resting habitats; alternatively, polar bears may become habituated to human-related noises.
Last, as polar bears spend more time on land and human activities in the Arctic increase, so does the risk of human-bear interactions. Polar bears are often attracted by the smells and sounds associated with human developments. This attraction to developments can increase the number of bears killed in an area. In some areas, polar bear monitors and patrols have proven effective in reducing the likelihood of human-polar bear interactions escalating into conflict.