FILE - Polar bear sow and cub newly emerged from their den in springtime on March 24, 2009 along the Arctic Coast of Alaska. LOS ANGELES - A July 20 research report highlights that high greenhouse gas emissions are contributing to the potential extinction of polar bears by the year 2100.Published in the Nature Climate Change journal, an abstract for “Fasting season length sets temporal limits for global polar bear persistence” describes how the animals are being impacted by global warming and declines in sea ice — something that polar bears require to capture seals, a main food source for the species.The researchers said, as of yet, it had not been possible to forecast when different subpopulations of polar bears would decline because data.