Tam on STEAM

Growing up in Tacoma, Washington, Tessa Hill spent hours in and on the waters of Puget Sound. She loved boating, walking on the beach, and digging in the sand.

“I was interested in all the things that were living in the sand and living on the rocks and living in the water,” she recalled. “I think kids are born scientists, and I was no different.”

Today you can still find Hill prowling the seashore. But now, instead of digging in the sand, she’s checking sensors in the water. As an oceanographer, Hill monitors conditions along the California Coast. The goal is to find out how climate change is affecting living things in our oceans.

Hill is an associate professor in the Department of Earth and Planetary Sciences at the University of California, Davis, and at the Bodega Marine Laboratory. She also leads a program to strengthen climate-change instruction in K-12 classrooms. Hill's work recently earned her a Presidential Early Career Award, the highest government honor for young scientists and engineers.


Animals always fascinated Hill. As a girl, she kept dogs, cats, and chickens as pets. She attended science camps on marine mammals, and later she served as a counselor at those camps. In high school, she worked in a veterinary clinic. She dreamed of becoming a veterinarian—maybe one who took care of ocean animals.

Her role models were scientists who studied nature. She read books by ocean explorer Jacques Cousteau and conservationist Rachel Carson. “I wondered what it would be like to be them,” Hill said.

Her parents weren't scientists, but they nurtured her interest. “My parents encouraged me to ask questions about how the world worked,” Hill said. “They also had a big influence by telling me I could do anything I wanted. The sky was the limit.”


After high school, Hill headed east to Eckerd College, a small school in Florida with a strong marine science department. She worked in the lab of Dr. Gregg Brooks, a marine geologist who analyzed sediment cores to figure out how the oceans have changed over time. Soon Hill was hooked on the work. She even spent summers in the lab.

Her job was to examine microfossils—remains of tiny sea creatures—in the ocean sediment. The organisms included foraminifera, tiny protists that come in an array of shapes, from discs to spirals to stars. Foraminiferabuild chalky shells from the chemicals in seawater. When they die, their shells form thick sediments on the ocean floor. Hill analyzed their fossilized shells to find out how the chemistry of the ocean has changed through the eons.

Brooks introduced Hill to two top experts on marine microfossils—Pamela Hallock Muller of the University of South Florida and Franco Medioli of Dalhousie University in Halifax, Nova Scotia. Both became mentors to Hill, who earned a B.S. in marine science in 1999.

When it was time for graduate school, Hill headed back to the West Coast, to the University of California, Santa Barbara. She wanted to work with Jim Kennett, a leader in the field of using the geologic record and microfossils to track changes in the oceans.

In graduate school, Hill divided her time between the ocean and the lab. “I would spend a lot of time out on research cruises, but then I would spend a lot of time sifting through sediments and picking out tiny little fossils,” she said. “I loved both of them. I really enjoy fieldwork. But I am also happy to stay up late plotting new data.” She received her Ph.D. in marine science in 2004.


In her current work at UC Davis, Hill studies how marine environments are changing as the oceans become more acidic. This is happening because the oceans are absorbing excess carbon dioxide when we burn carbon-based fuels to power our cars, homes, and businesses. As the ocean's chemistry changes, some sea creatures are doing fine, but others are struggling.

(See OCEANS PAST, PRESENT, AND FUTURE for more on Tessa Hill's research)

Hill received the Presidential Early Career Award partly for her research on ocean acidification. But the honor also recognized her work to give K-12 teachers better tools for teaching about climate change.

Under a program dreamed up by Hill and supported by the National Science Foundation, she works with undergraduates at UC Davis who plan to become teachers. Hill and the undergraduates develop curriculum based on real scientific data about things like sea temperature and ice cover in the Arctic. Sixth-grade teachers then test the curriculum.

The five-year program is in its third year. “The exciting thing is that by the end, we will have a full set of curriculum, and we will make it publicly available on a website,” Hill said.

She hopes to inspire students to take a scientific approach to the problems we face. “One way you empower students is to hand them real scientific information,” she said. “We are trying to get people to think about the oceans and climate change at an early age and hopefully go home and talk to their parents about it.”


Hill says that when she was younger, she didn’t think much about a being a woman in a field traditionally dominated by men. In graduate school, though, she noticed that a lot of female students were leaving the field.

“There are some practical reasons—students look at the faculty and they don’t see diverse examples of who becomes a scientist,” she said. “We have to work hard at showing students of all ages that different kinds of people can be scientists.”

Another factor is the idea that a science career is all-consuming, she said. “People worry that there isn’t room for other things in your life.”

Hill is finding ways to balance her research with those other things. She is married to Brian Gaylord, a marine ecologist at UC Davis, and they have two children, ages 5 and 8. Hill and her husband share their family responsibilities equally.

Hill makes a point of being there when her children have a school play or other big event. “Sometimes that might mean working at night,” she said. “Being a university scientist is very amenable to that.”

There’s another upside to being both a scientist and a parent, she added: “We include our kids in a lot of our fieldwork on the California coast… They get some great benefits from our scientific life.”

After all, as Tessa Hill says, kids are born scientists. Her story shows how that natural love of science can blossom into an exciting and rewarding career.


As she investigates changes in ocean environments, Tessa Hill keeps her eye on the big picture. “I’m looking at the past and the present and what may happen in the future,” she said.

The oceans are undergoing a change that is directly linked to what is happening in our atmosphere. By burning carbon-based fuels, people have steadily added carbon dioxide to the air. That excess carbon dioxide doesn't just vanish into outer space. In the atmosphere, it traps heat and warms our climate. But this carbon dioxide also dissolves in the oceans, slowly making them more and more acidic.

In her research at UC Davis and the Bodega Marine Laboratory, Hill uses a combination of approaches to understand what this change means for the health of the oceans.

To unlock the secrets of past marine environments, she sails on research vessels to collect sediment cores from the ocean floor. Then she analyzes microfossils in the sediment. “We look at what sort of stories they can tell us about how climates have changed in the past and what that means,” she said.

To figure out what is happening now, Hill’s research team, the Bodega Ocean Acidification Research group (BOAR), uses sensors along the California coast to monitor ocean temperature and oxygen and carbon dioxide levels. Hill also looks at how higher acidity is affecting sea creatures—including those that are part of our food supply.

Many ocean creatures, from corals to clams, take in calcium and carbonate from seawater to make calcium carbonate for building their shells and skeletons. But when the ocean becomes more acidic, there is less carbonate available for shell-building.

Hill has formed a partnership with an oyster farming company, Hog Island Oyster Co., to study how this change affects oysters in Northern California's Tomales Bay. The goal is “to try to find out how we can plan for a future where the ocean chemistry has changed,” she said.


What will the oceans of the future look like? Hill and her colleagues have come up with an ingenious way to get a glimpse. They have built a lab setup where they can change the temperature and acidity of seawater in a series of tanks. The tanks hold a variety of sea creatures, from plankton to the larvae of oysters and mussels—most of them too small to see. “We can expose lab animals to conditions 100 years from now,” Hill explained.

What Hill and her colleagues are finding is that some animals thrive but others struggle. “Sea urchins don’t seem to be bothered by future conditions,” she said. “Oysters and mussels—things that make shells—don’t do as well.”

As the oceans grow more acidic, some shellfish are making smaller shells or thinner shells, Hill said. They are more vulnerable to predators and to different kinds of stress.

“What does that mean?” Hill continued. “What will we be able to harvest sustainably from the oceans? We're trying to provide that information to policy-makers so they can use science to mange the oceans for the future.”

That's why Hill joined with ocean scientists from Canada, Washington, Oregon, and California to form the West Coast Ocean Acidification and Hypoxia Science Panel. The group helps governments plan for the future of the changing oceans.


Hill said the most important step we can take to protect the oceans is to cut our use of carbon-based fuels. But while we are working on that central problem, there are other things we can do.

“We need to make it so we aren't stressing the oceans in other ways,” she said. For instance, we can create marine protected areas that are off limits for fishing or oil drilling. And we can stop pollution and trash from flowing into the oceans.

Hill noted that researchers also are studying environments that can capture some of the carbon in the ocean and the air. These include salt marshes, sea grasses, and mangrove forests. “If we protect these environments, we might be able to slow down the changes in the oceans,” she said.

“We need to tackle the big global problem of carbon emissions and climate change,” Hill added. “But there are things we can also do locally. We can protect these places along our coasts.”

Watch a video about Tessa Hill's partnership with oyster farmers: