Dramatic changes in the freezing and thawing of arctic lakes have created a regional winter season 24 days shorter than a half century ago, scientists say. Climate change has also dramatically affected the thickness of lake ice at the coldest point in the season, a study led by the University of Waterloo in Ontario, Canada, found; in 2011, arctic lake ice was almost 15 inches thinner than it was in 1950. The study of more than 400 lakes of the North Slope of Alaska, sponsored by the European Space Agency, is the first time researchers have been able to document the magnitude of lake-ice changes in the region over such a long period of time, the university reported Monday. The research team used satellite radar imagery from ESA to determine the extent of freezing of lakes in the region. "At the end of the analysis, when looking at trend analysis results, we were stunned to observe such a dramatic ice decline during a period of only 20 years," Waterloo researcher Cristina Surdu said. Lakes lakes in the region froze almost six days later and broke up about 18 days earlier in the winter of 2011 compared to the winter of 1950, the researchers said. That could have an impact on people living in the region, Surdu said. "The changes in ice and the shortened winter affect Northern communities that depend on ice roads to transport goods," she said