<P> Polar bears are turning to alternate food sources because Arctic sea ice melts earlier and freezes later each year . As a result, they have less time to hunt their historically preferred prey of seal pups, and must spend more time on land and hunt other animals . As a result, the diet is less nutritional, which leads to reduced body size and reproduction, thus indicating population decline in polar bears . </P> <P> Melting Arctic ice caps are likely to increase traffic through the Arctic Ocean . An early study by James Hansen and colleagues suggested that warming of 5 to 10 ° C, which they expected as the range of Arctic temperature change corresponding to doubled CO concentrations, could open the Northwest Passage. A 2016 study concludes that Arctic warming and sea ice decline will lead to "remarkable shifts in trade flows between Asia and Europe, diversion of trade within Europe, heavy shipping traffic in the Arctic and a substantial drop in Suez traffic . Projected shifts in trade also imply substantial pressure on an already threatened Arctic ecosystem ." In August 2017, the first ship traversed the Northern Sea Route without the use of ice - breakers . Also in 2017, the Finnish icebreaker MSV Nordica, set a record for the earliest crossing of the Northwest Passage . According to the New York Times, this forebodes more shipping through the Arctic, as the sea ice melts and makes shipping easier . A 2016 report by the Copenhagen Business School found that large - scale trans - Arctic shipping will become economically viable by 2040 . </P>

During what time of the year is the arctic sea ice extent normally at its lowest