Climate change-induced sea ice melt is causing the starving deaths of polar bears, according to renowned bear expert, Dr. Ian Stirling. Over the last year, warming temperatures have reduced the amount of Arctic sea ice to record lows. A lack of sea ice means a lack of seals, and, for polar bears, no access to their food source.

2012 saw the lowest amount of sea ice ever recorded, The Guardian reports. Because polar bears feed almost exclusively on seals, which live on sea ice, bears are having to travel extreme distances in an attempt to reach food.

In a Guardian report released Tuesday, Dr. Stirling references a 16-year-old bear found dead in Svalbard, Norway. “From his lying position in death, the bear appears to simply have starved and died where he dropped,” Stirling said. “He had no external suggestion of any remaining fat, having been reduced to little more than skin and bone.”

The bear in question had been captured and studied in previous years, so that scientists knew his health status and normal range. When his body was discovered in northern Svalbard in July, researchers knew that he was searching for food far beyond his normal range when he died of starvation.

The Norwegian Meteorological Institute told The Guardian that the sea ice break up around Svalbard happened both early and very quickly this year. “Most of the fjords and inter-island channels in Svalbard did not freeze normally last winter and so many potential areas known to that bear for hunting seals in spring do not appear to have been as productive as in a normal winter,” Stirling stated in the report.

In March, the Journal of Animal Ecology released a report on the effect of melting sea ice on polar bears in Canada. A team of researchers studied the migration patterns of the bears and found that they were arriving on land earlier and leaving later, threatening their access to food.

“Polar bears hunt their main food source, seals, primarily while on sea ice. Changes in the ice are driving the bears to spend more time on land, where they have to go longer without eating and rely on fat reserves to tide them over,” LiveScience reports.

Researchers at the University of Alberta, Canada, conducted research by putting tracking collars on 109 female polar bears – the males cannot wear collars because their necks are larger than their heads – and taking measurements from blood samples and fat biopsies, which hold clues to the bears’ nutrition and diet.

“When we look at the migration patterns of the collared bears, it appears as though bears in recent years are arriving on shore earlier in the summer and leaving later in the autumn,” study leader Seth Cherry told LiveScience. “These are precisely the kind of changes one would expect to see as a result of a warming climate.”

The University of Alberta team found that not only the distribution of sea ice, but how fast the ice melts and forms affects the bears’ migration. While the bears are on land, they are fasting. This makes pregnant females even more vulnerable, as they must stay on land to give birth to their cubs and nurse them during November and December, the time when other bears typically resume hunting.

Alisha is a writer and researcher with Ring of Fire. Follow her on Twitter @childoftheearth.