Time Magazine: Spring came early to Walden Pond in 2012. Scientists -- both amateur and professional -- have kept records of flowering times for plants in Walden Pond, near the Massachusetts town of Concord, since Henry David Thoreau began doing it in 1852. The result is one of the best continuous datasets of nature in the U.S, which has made Thoreau`s retreat an excellent lab for testing the effects of manmade climate change on the environment. In a new paper published in the Proceedings of the National Academy...