Citing a recent study by the government of Nunavut in Canada, conservative media are claiming that the number of polar bears is "increasing." The takeaway, according to these media outlets, is that concerns about the fate of polar bears in a warming world are overblown. But polar bear scientist Steven Amstrup says these commentators are mistaken.
The polar bears located west of the Hudson Bay are one of 19 polar bear subpopulations, and one of 8 subpopulations that are thought to be shrinking, according to a comprehensive review conducted in 2009. (One population was found to be increasing, three are stable, and there isn't enough data to assess the other seven). Amstrup and others previously analyzed bears captured from 1984-2004 and found that the West Hudson Bay population declined from 1,194 in 1987 to 935 in 2004.
But a new survey by the government of Nunavut, a largely Inuit territory in Northern Canada, puts the population size as of last August at 1,013, according to a widely circulated article in Canada's Globe and Mail. This new estimate is derived from a plausible range of 717 to 1,430 bears and, importantly, comes from an aerial survey, unlike the previous studies which involved capturing and recapturing bears.
Amstrup said media outlets claiming the aerial survey shows an increasing population are mistaking a single point estimate for a trend. "The population size is just a number. It is a valuable number to have, but from the standpoint of population welfare, it is the trend in numbers that is critical," he wrote in an email. Because previous estimates used a different methodology, and covered a different geographic area, they cannot be easily compared to the latest figures, contrary to the media narrative. When the aerial survey is repeated in later years, it will then be able to tell us more about how the population size is changing. In the meantime, the Canadian government is expected to release its latest capture-recapture data next month.
Population estimates are used to determine how many polar bears can be killed each year. Hunting polar bears is a significant source of income among the Inuit, who have been skeptical of dire predictions of popopulation decline.
Amstrup emphasizes that "in the bigger picture, whether any one population is currently declining, stable or increasing is beside the point," adding, "it is criticial to remember that our concern about polar bears is focused on the future." The scientists who spend their lives studying polar bears have been unable to envision how the population numbers can withstand the long-term decline of the sea ice.
More detailed responses from Amstrup below:
As many faith leaders have recognized, climate change presents a massive ethical challenge since those least responsible for global warming are among the most vulnerable to its consequences, including water scarcity, climate-sensitive diseases, and sea level rise. Yet in response to the recent international climate talks, conservative media outlets are mocking developing countries for seeking adaptation assistance, saying they just want to "cash in" on "climate gold."