What Walden Pond Reveals About Global Warming

Click here to watch a slide show about conservation biologist Richard Primack, at work in Minute Man National Historical Park in Concord, Mass.

Evidence of climate change isn’t always as ominous, or as remote, as melting polar ice caps or rapidly rising sea temperatures. In fact, says conservation biologist Richard Primack, quiet but unmistakable signs of climate change can be seen every day, in every backyard, in towns across America. Primack, a College of Arts and Sciences professor of biology, is working on an award-winning research project to demonstrate the local effects of global climate change. He’s using Concord, Mass., as a living laboratory, and he has teamed up with no less a lab partner than Henry David Thoreau. His research will be the topic of the second lecture in the new Discoveries series, hosted by CAS and the CAS Alumni Association, on Thursday, April 17, at 7 p.m.

As a naturalist, Thoreau was compulsive — the perfect lab mate. He made daily entries in his journal about what he saw in the landscape around Walden Pond during the 1850s, recording bird migration patterns, flowering cycles of plants, and observations about wildlife and temperature. Primack and his collaborator, Abraham Miller-Rushing (GRS’07), are trying to do the same, making thrice-weekly visits to Concord with their field notebooks and taking careful note of when flowers are blooming and when birds are returning each migrating season. By comparing their data with that of Thoreau, Primack and Miller-Rushing are showing that global warming is already influencing the behavior of plants and wildlife in Boston and its environs.

“There is a lot of evidence that global climate change is starting to affect biological systems,” says Primack, who won a 2006 Guggenheim Fellowship to support his research. “A lot of it seems far away, or not immediately serious. What we’re showing is that in one area, one local town, you can see so much evidence of it.” By repeating Thoreau’s experiments and recording the difference in blooming times and in the seasonal appearance of birds, they’ve been able to showcase the effects of a warming climate: on average, they say, “spring events” now begin one week earlier than they did in Thoreau’s time.

“Flowering times are one of the most sensitive indicators of climate change,” Primack says, noting that earlier annual bloom times (and the earlier arrival of birds each spring) correlate to rising annual temperatures. As blooming patterns shift, other natural processes are affected as well, including pollination and seed dispersal, resulting in potentially dramatic changes to the ecosystem. Thanks to Thoreau’s meticulous record-keeping, Primack, Miller-Rushing, and their team of undergraduate research assistants can essentially go back in time, making comparisons and drawing conclusions about which plant species are most sensitive to climate change. They’re also taking note of overall changes in the abundance of wildflowers in the local landscape, wandering Thoreau’s old haunts at Walden Pond and exploring the meadows of the Minute Man National Historical Park. There, at the site of the beginning battle of the Revolutionary War, Concord’s North Bridge, unusual and historically significant wildflowers find the terrain conducive to growth, making the area “botanically extremely valuable,” Primack says.

His focus — like Thoreau’s before him — is keenly local. His research leaves little wiggle room for those who doubt the effects of a warming climate. “We’re working in a place people can relate to,” Primack says, “and using species that are familiar to people: apple trees, hummingbirds, ducks. It really brings home the message of global climate change.”

Richard Primack will speak on Thursday, April 17, at 7 p.m. in the School of Management auditorium, 595 Commonwealth Ave., followed by a light reception. The event costs $10 and is open to the public. Register online here.

Bari Walsh can be reached at bawalsh@bu.edu.