Tool to save polar bear dens is more miss than hit
In the debate over the possibility of oil drilling in the Arctic National Wildlife Refuge in Alaska, polar bears play an important, if silent, role.
At issue is whether oil development, especially seismic testing to find oil reserves that would be conducted long before any drilling occurred, can be undertaken without harming the animals, which have been hit hard by climate change.
A new study casts doubt on the effectiveness of what is considered a state-of-theart tool to help industry avoid injuring or disturbing polar bears by detecting their dens in the snow. Over more than a decade on the North Slope of Alaska, the study found, oil companies located fewer than half of the known dens of maternal bears and their infant cubs using airborne instruments called forward-looking infrared, or FLIR, cameras.
“We wanted to make sure that we throw up a cautionary flag,” said Tom Smith, a wildlife ecologist at Brigham Young University and the lead author of the study, which was published last week in the journal PLOS One. The oil industry
“needs to acknowledge that even with the best conditions, you’re going to miss bears, added Smith, who is also a scientific adviser to Polar Bears International, a conservation group that provided some of the funding for the study.
Pregnant polar bears dig dens in the snow late in the year and emerge with their cubs the following spring. Undetected dens could be disturbed or even crushed during a seismic survey, in which large trucks traverse the land in a grid pattern, accompanied by movable supply depots and camps for workers.
On the North Slope of Alaska, where oil drilling has been conducted since the 1970s, seismic surveys are only allowed in winter when there is enough snow to protect the delicate Arctic tundra.
FLIR cameras, which are carried by airplanes or helicopters, can detect heat under the snow. But Smith said weather conditions have to be just right — not much wind and little moisture — for the cameras to get good readings.
Other factors, like too much snow cover, can also cause the cameras to miss dens. “If the snow overlying a den is more than a meter thick, FLIR is not going to see it,” Smith said.
Detection is likely to become more difficult as the Arctic continues to warm under climate change, as warmer air contains more heat-scattering moisture, he said.
Using industry reports of FLIR surveys from 2004 to 2016 and comparing them with on-the-ground documentation of dens across the North Slope, the researchers found that only 45 percent of the 33 dens were located by FLIR cameras. The surveys also produced a number of false positives, because sources like exposed soil and rocks or even discarded steel drums can radiate heat that might be interpreted as signs of a den.
The Arctic refuge is an important denning area for the Southern Beaufort Sea subpopulation of polar bears, one of the most threatened in the world. Reduction in sea ice coverage, a result of rapid warming in the Arctic, has led to a sharp decline in the population, as it has become more difficult for the bears to reach seals and other food at sea.
The potential harm to the bear population has become a major issue amid the Trump administration’s efforts to allow oil drilling in the Arctic refuge, an area the size of South Carolina that is largely untouched by human activities.
A tax bill passed by Congress in 2017 allowed the Interior Department to develop plans for oil development in a part of the refuge along its northern coast called the 1002 Area. The administration had hoped to begin selling leases last year, despite opposition from Democratic lawmakers, threats of legal action by environmental groups and uncertainty about how much oil underlies the area. A New York Times investigation uncovered evidence that the only oil well ever allowed in the refuge, one that was drilled in the mid 1980s to look for signs of oil reserves, had disappointing results.
Lease sales were never conducted and the administration’s plan remains stalled. An environmentalimpact statement, required before sales can be held, has been prepared by the Interior Department but no final decision has been made.
If a seismic survey does take place in the refuge, another paper, by Interior Department scientists, has suggested ways it could reduce disturbances to polar bears.
The study, published in December in The Journal of Wildlife Management, used computer simulations of survey designs that varied in where and when the seismic trucks rolled, to avoid known denning areas or survey them only after bears have emerged, usually in early March. It found that a survey design with the most specific restrictions on locations and times reduced the number of dens disturbed by more than 90 percent compared with a survey with no restrictions.