Tracking Climate Change with Citizen Science

On a rainy night in 1970, on her farm in southern Massachusetts, Mrs. Kathleen Anderson heard the first spring peeper calls and marked in her notebook, “March 27th.” She did the same each spring for the next 32 years, and in 2001, her notebook read: “Spring peeper, March 3rd.”

She wasn’t alone. Around the world, people in backyards and parks have been recording changes that scientists now regard as important data. Temperature models indicate an increase in global average temperature of about 1.3ºF in the twentieth century. Those figures are the result of complex analyses, but corroborating evidence—in the changing schedules of birds, frogs, insects, and plants—is adding up as well.

It wasn’t just Mrs. Anderson’s frogs that were starting their season early. When Mrs. Anderson shared her journal observations of birds, insects, amphibians, and plants with researchers at Boston University, her records helped them determine that 22 different species were arriving or becoming active earlier over the past few decades.

That’s why the Cornell Lab of Ornithology is part of Communicating Climate Change, a National Science Foundation-funded citizen-science project to help record local impacts of climate change.

To be certain that observed changes are related to global climate change and not a more local cause, scientists need observations from across continents and over long periods. It’s only through citizen science, in which people everywhere use standardized methods to observe natural events, that scientists can fill in these details on a scale large enough for global patterns to become evident.

Early citizen-science projects yield some great examples. Bird enthusiasts such as Vivian Pitzrick and Betsy Brooks joined the Nest Record Card Program and searched for bird nests each year. Their regular observations helped show that between 1959 and 1991, Tree Swallows began laying eggs on average 9 days earlier. The results appeared in the Proceedings of the Royal Society of London.

Citizen scientists notice more than just birds. An amphibian project found four frog species calling 10–13 days earlier now than in the beginning of the 1900s. Across Europe, amateur botanists have recorded 160 plant species leafing, blooming, and fruiting earlier. A study of caterpillars (in Population Ecology) suggests the climate zones monarchs survive in will shift northward in the next 50 years. Each story on its own is important. Together, they suggest largescale changes are taking place.

Like any good science, these observations suggest new questions: What other, more obscure natural events are changing? Are plant, insect, reptile, and bird events all changing timing together, or in different ways? Are species adapting to climate change, or being hurt by it?

And one more: How do things compare in your neighborhood? To find out, scientists need your help, in projects such as the Christmas Bird Count, Project BudBurst, and our own NestWatch and Project FeederWatch, among others. Even small efforts can be of huge importance—just ask those spring peepers whose resounding chorus inspired Mrs. Anderson.

Jennifer Shirk leads the Cornell Lab’s Citizen Science Toolkit project.

Originally published in the Winter 2011 issue of BirdScope.