Climate-change studies show leaf-out times of trees and shrubs at Walden Pond are an average of 18 days earlier than when Henry David Thoreau made his observations there in the 1850s.
Fuente : http://feeds.sciencedaily.com/~r/sciencedaily/~3/j...
Fuente : http://feeds.sciencedaily.com/~r/sciencedaily/~3/j...