Sault Star: U.S. scientists say critical Arctic sea ice has made a tenuous partial recovery this winter, following last summer’s record melt. But that is an illusion – like a Hollywood movie set – says scientist Walter Meier of the National Snow and Ice Data Center in Washington. The ice is very thin and vulnerable to heavy melting again this summer. Overall, Arctic sea ice has shrunk precipitously in the past decade and scientists blame global warming caused by humans. Last …