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In Hudson Bay,the ice breaks up three weeks earlier in the spring now than it did 20 years ago.Polar bears in Hudson Bay fast⑤ during the summer,waiting for ice to form in the fall to hunt.Every year,the summer gets longer,and the bears get skinnier⑥.Over the past 25 years,the average weight of the female bears has dropped 68 kg.This loss affects their ability to reproduce,and already the number of births has dropped by 15 percent.Unless the bears can learn to survive these climate changes,these giants of the ice may one day disappear.