If humans don’t reverse global warming and stop the loss of sea ice, it’s unlikely polar bears will continue as a species.That’s the blunt assessment in the U.S. Fish and Wildlife Service’s draft recovery plan for polar bears filed Thursday. The agency listed the animals as threatened in 2008.Greenhouse gas emissions contribute to global warming, which is reducing the amount of summer sea ice in the Arctic. Polar bears use sea ice for feeding, mating and giving birth.The plan says the first and foremost action for polar bear recovery is to stop Arctic warming. It says accomplishing that will require global action.The estimated worldwide population of polar bears is about 20,000 to 25,000. The only U.S. state with the iconic animals is Alaska, and government scientists say those bears could be among the first to see global warming’s ill effects.