Climate Central: In a sign of how swiftly and extensively climate change is reshaping the Arctic environment, a new study has found that the region's mighty boreal forests -- stands of mighty spruce, fir, and larch trees that serve as the gateway to the Arctic Circle -- have been burning at an unprecedented rate during the past few decades. The study, published Monday in the Proceedings of the National Academy of Sciences, found that the boreal forests have not burned at today's high rates for at least the past 10,000...