evidence: A new analysis, using global climate models, predicts that most of the Arctic Ocean could become ice-free during summer by 2050. This new forecast, which used continuous and consistent satellite observations generated via ESA’s Climate Change Initiative, suggests that the future of the Arctic’s sea-ice cover critically depends on future carbon dioxide emissions. Each year, Arctic sea ice goes through a seasonal cycle, growing in area and thickness through the cooler winter months before shrinking back again as temperatures rise in the spring and summer, with the minima occurring usually in September. [...] Project coordinator, Dirk Notz from the University of Hamburg, comments, "We are very surprised by these findings. Even if we reduce emissions substantially, keeping global warming levels below 2°C, Arctic sea ice will nevertheless disappear occasionally in summers before 2050."