Nineteenth century philosopher Henry David Thoreau is best known for his essays on Walden Pond near Concord, Massachusetts. But during his time there, Thoreau also created what one scientist calls a gold mine for climate change researchers.

Page from Thoreau book

Thoreau meticulously noted the flowering times of more than 300 plant species, and the leafing out times of 50 species of trees and shrubs.

Primack: “As soon as we saw these data from all of these very detailed tables that he produced, we knew that what we should be doing is to repeat these same observations.”

That’s Richard Primack of Boston University. His research shows that plants in Concord are now flowering – and trees leafing out – two weeks earlier on average than in Thoreau’s time.

The results are consistent with rising temperatures, and show the pervasive effects of climate change.

Primack: “It’s not something which is going to happen in coming decades. It’s not going to happen by the end of the century. It’s already happening now. The effects of climate change are all around us if you’re only willing to open your eyes and see it.”

'The effects of climate change are all around us if you're only willing to open your eyes.' Click To Tweet

It’s a realization that echoes Thoreau’s own words. He wrote, “We cannot see anything until we are possessed with the idea of it, take it into our heads – and then we can hardly see anything else.”

Reporting credit: Rosie Simon/ChavoBart Digital Media.
Photo: Original title page of Walden featuring a picture drawn by Thoreau’s sister Sophia.

Topics: Climate Science, Species & Ecosystems