The cold winter and spring have caused a record amount of ice to remain on the Great Lakes, wreaking havoc with shipping and wildlife, according to data from Environment Canada, a government agency. “It’s been a very tough ice season on shipping,” especially in the upper Lakes, says George Leshkevich, a scientist with the Great Lakes Environmental Research Laboratory of the National Oceanic and Atmospheric Administration.  He added that the unusual ice cover “has had societal, economic and ecological impacts.” As of Wednesday, ice covered 33.9% of the Great Lakes, the largest ice cover so late in the season since accurate measurements from satellites began in the late 1970s. Usually by this time, all but about 2% of the Great Lakes are free of ice. More