Polar Bear Seal Diet Has Higher Contaminant Load: Impact of Global Warming 21 Sep 2013 Polar bears have to contend with a lot of threats. Now, they may have to deal with just one more. Over the past 30 years, polar bears have increasingly exchanged ring seal with harp seal and hooded seal in their diets. Scientists have now discovered that this change has exposed polar bears to far more contaminants, which may impact their health. The polar bear is a species that's being drastically impacted by changing rising temperatures. Its habitat is shrinking and food sources are moving to adapt to the shifting climate. Because of this, polar bears have also had to adapt, though their populations are continuing to decline.