As a child, University of Delaware alumna Susan Trumbore devoured books by author Gerald Durrell, a British naturalist and zookeeper who wrote about his life on the Greek island of Corfu. As a student at Newark High School she developed a love of earth science from her teacher Bill Harrison. But it was as a geology major at UD that Trumbore discovered her true calling—when she became fascinated with radiometric dating.

Radiometric dating is a process that uses the decay of radioactive materials to date materials. Trumbore, who earned her bachelor’s degree in geology at UD in 1981 and now directs the prestigious Max Planck Institute for Biogeochemistry in Jena, Germany, helped pioneer the use of carbon isotopes and radioactive tracers left behind in the atmosphere from nuclear weapons testing in the mid-20th century, as a means to track how carbon naturally moves between soil, air and the sea. Today, this important tool for measuring the Earth’s carbon cycle is considered indispensable to the study of climate change.

For this work, Trumbore was selected to receive the Franklin Institute’s 2018 Benjamin Franklin Medal in Earth and Environmental Science. More than 75 people gathered on UD’s Newark campus Wednesday, April 18, to honor Trumbore during a symposium titled “The Earth’s Carbon Cycle in the 21st Century.”

College of Earth, Ocean, and Environment Dean Estella Atekwana opened the symposium, telling attendees it seemed fitting to honor Trumbore in Newark, since “UD lit the spark that grew into the very consequential fire of Dr. Trumbore’s career.”

The UD event was among multiple events held in the region as part of the Franklin Institute Awards Week celebration, April 16–20. Since the Franklin Institute awards began in 1824, more than 2,000 scientists have been honored for their work. As a laureate, Trumbore joins an impressive list of awardees including Nikola Tesla, Thomas Edison, Marie Curie, Jacques Cousteau and Jane Goodall, to name a few.

Viewing the world through “radiocarbon glasses”

Throughout the symposium, sponsored by the College of Earth, Ocean, and Environment, the Delaware Environmental Institute, the Department of Geological Sciences and the Franklin Institute, scientists presented research on a variety of carbon-related work in the region and across the globe.

Trumbore started the discussion by recounting some memorable childhood, academic and career milestones—in carbon dioxide concentrations—as her father, Conrad Trumbore, professor emeritus in UD’s chemistry department, beamed from the audience. When Trumbore moved to Newark, Delaware, as a toddler in the late 1950s, for example, the concentration of carbon dioxide in the atmosphere was roughly 317 parts per million (ppm). But by 1991 when she joined the faculty at University of California, Irvine, the concentration had jumped to 356 ppm.

“In my lifetime, the amount of carbon dioxide [in the atmosphere] has changed as much as it did between glacial and interglacial periods where it took thousands of years for that to happen…The pace of change is fast right now on the Earth and it’s very hard to keep up. We’re all trying to balance this carbon budget, and it keeps changing and accelerating each year,” Trumbore said.

Trumbore has traveled the world to study various soils and their interaction with the environment. She has explored the Brazilian Amazon, conducted research in the South African savannahs, and she even was among the scientists charged with carbon-dating the Shroud of Turin, which some believe to bear the image of Jesus Christ.

Radiocarbon, she said, provides a common thread to put scientists’ individual work in context of the global carbon cycle as a whole, whether that work focuses on soils and plants, ocean acidification or better understanding what’s happening in coastal ecosystems or in the atmosphere.

“It’s the same chemistry, but because it’s radioactive it has a different time history within the atmosphere, so we can learn things we can’t learn by looking at carbon alone,” Trumbore said.

Julia Guimond, a doctoral student in the Department of Geological Sciences, has been exploring how plants and animals living in a marsh at the St. Jones Reserve near Dover—a component of the Delaware National Estuarine Research Reserve—affect water movement and chemical changes in the marsh. Salt marshes are considered valuable for their ability to store carbon dioxide from the atmosphere. Understanding how this stored carbon is affected by the physical movement of water during tidal cycles is important to predicting how these conditions might change with sea level rise and increased precipitation.

Guimond said it was “eye opening” to hear from researchers at the symposium who are attacking similar problems across different disciplines. She was especially intrigued by UD postdoctoral researcher Janet Reimer’s discussion of UD research exploring how the coastal ocean carbon cycle is responding to additional carbon and nutrient inputs from land and ocean acidification in the deep ocean, and how this might overlap with her own work.

“Coastal ecosystems are so tightly interconnected that changes in intertidal ecosystems, such as the salt marshes that we study, may impact what is happening miles away in the coastal ocean,” said Guimond. 

The same is true globally, and solutions to mitigate climate change will require greater collaboration, the researchers said. Margaret Torn, senior advisor in the Climate and Ecosystem Sciences Division at Lawrence Berkeley National Laboratory, pointed to her work on the Deep Decarbonization Pathways project as a positive step in this direction. The project is a collaborative effort involving more than 15 countries, including the United States, focused on identifying practical ways to deeply reduce greenhouse gas emissions. Torn said that fostering a low-carbon economy will require aggressive energy efficiency; a focus on clean energy sources such as solar, wind and nuclear; and reduced use of fossil fuels such as coal or gas. And though it will not be easy, it is doable.

“Perhaps there is another student here today who will help us take on the next challenge in addressing climate change,” Dean Atekwana mused, “because she had the engagement of talented faculty, the resources of a tier-one research institution and the example of scientists like Dr. Trumbore to inspire and guide her.”