Massive declines in population of polar bears at the poles have been predicted by the first ever systematic assessment of ice declines at Arctic and Antarctic.
The study by US Fish and Wildlife Service in Anchorage, Alaska projected three population scenarios till 2050, and all of them were bad news for the snow-white carnivores. The findings are startling as they predict that by 2050 an estimated 26,000 polar bears will be wiped out from the poles over the course of three generation.
The assessment sits in line with previous studies that have predicted a similar decline including a recent review that was carried out by the International Union for the Conservation of Nature (IUCN). IUCN has already classified Ursus maritimus – the sea-faring polar bear – as “vulnerable”, or at high risk of extinction in the wild. While the review by IUCN predicted a decline, the latest study published in Royal Society’s Biology Letters is the most comprehensive to date.
For their study, scientists combined 35 years of satellite data on Arctic sea ice with all known shifts in 19 distinct polar bears groupings scattered across four ecological zones in the Arctic. With survival of polar bears depending a lot on sea ice, there is a strong association on the survival of these animals and the level of sea ice cover. With decline in sea ice levels, which they normally use as floating platforms to hunt seals, polar bears find it increasingly difficult to find food.
Researchers projected three population scenarios by 2050, but neither of these scenarios show any positives for the polar bears. The first assumed a proportional decline in sea ice and polar bears. While there have been year-on-year variation in sea ice extent, the overall trend shows a decline with the ten lowest Arctic ice extents over the satellite record have all occurred since 2007. This week, the US National Snow and Ice Data Center reported that sea ice extent in October and November was the lowest ever registered for both months.
With increasing temperatures across the globe, global warming is taking a toll on sea ice extent and this will most likely have an impact on the survival of polar bears. On current trends, the Arctic could see its first ice-free summers sometime in the 2030s, say climate scientists.
In the second and third scenarios, the same sea ice projections were matched with available data about changes in specific polar bear populations spanning at least a decade, in small areas in one case, and across the four larger “eco-zones” in the second.
Averaging all three scenarios, the probability that polar bear numbers would drop by a third in 35 to 41 years is more than 70 per cent, the study concluded.
Unfortunately, polar bears face other threats besides a habitat radically altered by the release of heat-trapping greenhouse gases.