A comparison of detailed notes taken by naturalist Henry David Thoreau with current weather and flower-blooming data has enabled scientists to document the earlier arrival of spring in eastern Massachusetts over 
the past 150 years. After studying Thoreau’s records and those of another local naturalist from more than a century ago, Boston University researchers found that the flowering date for 43 common species had moved up by an average of 10 days in the last 150 years. Those species that have not adapted to the changing climate are disappearing altogether, the study found. While 21 species of orchid grew wild in Thoreau’s hometown of Concord, Mass., during his time, today there are only six, said Richard Primack, a professor of biology at Boston University. According to scientists, the average temperature in Concord, a Boston suburb, has warmed by 4.3 degrees F since the 1860s. The report, which updates an earlier study to include data collected from 2008 to 2010, is published in the journal BioScience.
Henry David Thoreau