Thoreau’s Journals Reveal Climate Change

Spring’s natural events are arriving one week earlier

Henry David Thoreau ventured into the woods near Concord, Mass., to “see if I could not learn what it had to teach me.” More than 150 years later, two Boston University scientists say, Thoreau’s meticulous environmental observations continue to instruct. 

Richard Primack, a College of Arts and Sciences professor of biology, and Abe Miller-Rushing (GRS’07), a doctoral student in biology, are using Thoreau’s notations of plant flowering cycles and bird migration patterns as a basis for research into the local effects of global climate change. 

Thoreau inspired amateur naturalists in and around Concord, many of whom have kept notes on several of the same species over the years. Those journals, along with musty herbarium specimens, old farmers’ diaries, and sepia-toned photographs, have provided Primack and Miller-Rushing with historical climate data they then compare with present-day observations from the field.

What have the two scientists found? On average, they say, “spring events” now begin one week earlier than they did in Thoreau’s time. Much of their research, which has been conducted over the past four years and which earned Primack a 2006 Guggenheim Fellowship, appears in the November 2006 issue of the American Journal of Botany. Primack and Miller-Rushing will also detail their findings in an upcoming book.

“We hear about the effects of global climate change on hurricane systems, the Gulf Stream, the melting of glaciers,” says Primack. “But a lot of this information seems very far away. We want to use Massachusetts, and Concord in particular, as a case study which demonstrates that global warming is happening, and it can’t be ignored.”

This story was first published on BU Today on November 14, 2006.

Chris Berdik can be reached at

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Thoreau’s Journals Reveal Climate Change