Sea ice is drifting further north so polar bears travel further to hunt.
The huge glacial ice sheets in Greenland and Antarctica are reacting more slowly to the warming atmosphere and oceans but scientists are watching them closely as they will heavily influence sea level rise if there's significant melting. You'd work up quite an appetite - and get hungrier the more distance you'd cover. But he added, "I think it confirms all the reasons to be concerned about polar bears from a conservation perspective are intact".
This is where there's still a lot of work to be done, the WWF said.
"Just to break even they have to capture at least one seal every five to 10 days - and that's just to break even", said study co-author George Durner, a USGS research zoologist.
By tracking nine female bears in the Beaufort Sea region off the coast of Alaska last April, the researchers found that the bears' metabolic rates-that is, the amount of energy their bodies require to function-were about 60 percent higher than scientists had previously assumed.
According to a study by the University of Colorado, the extent of sea ice across the Arctic is decreasing at a rate of 14% per decade.
The metabolic rates Pagano and his fellow researchers observed were, on average, 50 percent higher than previous studies predicted.
Arctic sea ice is getting thinner every year, and there have been significant losses in the overall area covered by ice, according to the latest data. Their most recent population estimate indicates the polar bear population has declined by about 40 percent over the past decade.More news: Haas leads by two at Phoenix Open
Polar bears are the iconic animals of climate change. The researcher's team mentioned that, this time polar bears are sending a message to humans what they are doing to the world and how their activity is destroying wildlife. That bear turned out to probably have been ill. New research has established the physiological factors that make the Arctic's top predator so vulnerable to changes in the sea ice. This assumption was found not to be true. Five populations are thought to be stable and there's not enough known about the others to judge. And yet they are uniquely vulnerable in their nearly total reliance on one prey species.
Scientists were given an insight into the bears' weight problems by fitting nine females with satellite collars fixed with video cameras over the past three springs in Alaska's Prudhoe Bay.
"That [number] tells us a lot about modelling into the future what's going to happen with the bears".
Over the course of the study, four of the nine seals did not reach that calorie level and lost a combined mass of 20 kilograms (44 pounds), which "reinforced the starvation lifestyle the polar bears have", Pagano said.
Moreover, climate change appears to be having dramatic effects on the Arctic sea-ice, forcing polar bears to move greater distances as they hunt, and making it harder for them to catch prey. They fitted the bears with collars carrying Global Positioning System trackers, accelerometers and video cameras. As a leader in conservation, the work of San Diego Zoo Global includes on-site wildlife conservation efforts (representing both plants and animals) at the San Diego Zoo, San Diego Zoo Safari Park, and San Diego Zoo Institute for Conservation Research, as well as worldwide field programs on six continents. They also used metabolic tracers that helped them determine how much energy the bears were expending.
"An increasing proportion of bears are unable to meet their energy demands", the authors concluded.
"In a population, there are always individuals who cope better or worse with any changes".
Polar bears rely nearly exclusively on a calorie-loaded diet of seals. This is the time when bears give birth pups.