© NAT AND CODY GANTZGrowing up on the Pacific coast, Tessa Hill developed a fascination with the sea and its wildlife. In the late ’90s, eager to see another part of the country—and another ocean—she moved to Eckerd College in Saint Petersburg, Florida, to study marine science. There, she became interested in the relationship between oceans and environmental change. “I wanted to learn more about the Earth’s climate system,” she says. “How it operated in the past, and how we might be modifying that system today.”
In 1999, Hill moved back west for a PhD at the University of California, Santa Barbara, where she worked with paleoceanographer James Kennett to document the contribution of ocean sources of methane to climate change throughout Earth’s history. “She’s very capable of choosing questions of major significance,” Kennett says of Hill, adding that on the methane project, “she just jumped right in.” During her dissertation work, Hill discovered that methane gas leaves a signature in the fossilized shells of Foraminifera—amoeboid protists found in marine sediments—that can be used to track changes in methane levels in the world’s oceans through time.1
Graduating in 2004, she moved to the University of California, Davis, to investigate more-current climate trends. “I was interested in asking questions about modern impacts ...
