Keeping Time

You’re probably familiar with how growth rings in trees capture the passage of time on land, but what catalogs the history of our oceans? For marine scientists, it’s growth bands within coral skeletons. These rings chronicle a coral’s age, and the skeleton’s chemistry functions as an environmental journal, logging evidence of unusual temperature events and other oceanic conditions occurring over the coral’s lifespan.

Neda Mobasher is intimately familiar with the hidden histories corals can reveal. Peering through her diving mask, she collects coral samples from remote islands off the coast of Ecuador and due south of Hawaii, locations separated by nearly 5,000 miles of Pacific Ocean. Once back at Florida State University, she’ll analyze the samples’ chemical fingerprints to reconstruct thousands of years of climate history. 

“As corals take in seawater, the water’s environmental properties become part of their skeletal chemistry, which we then extract from both sub-fossil and living corals,” said Mobasher, a first-year doctoral student in chemical oceanography. “Because these corals record sea-surface temperature variability at monthly resolution, we can use them to reconstruct changes in the El Niño-Southern Oscillation over time.”

Mobasher uses coral samples from the Galápagos Islands and Kiritimati, also known as Christmas Island, to reconstruct the El Niño-Southern Oscillation, or ENSO, a recurring climate pattern in the tropical Pacific. ENSO’s warm phase is called El Niño and the cold phase La Niña. This pattern of oceanic warming and cooling directly influences global weather. In the southern U.S., El Niño typically brings colder, rainier conditions and fewer Atlantic hurricanes: La Niña’s impacts are opposite.

Research suggests human activity has contributed to ENSO’s intensification since the mid-20th century, but it’s difficult to pinpoint how and to what extent because precise ocean-atmosphere measurements only date back to the satellite era’s start in the mid-1960s. Mobasher’s work helps fill millennia-sized gaps in sea-surface temperature estimates from the tropical Pacific Ocean to guide future predictions, ultimately supporting accurate natural disaster forecasting and climate projections.

“Reliable data only goes back so far, but corals are one of the highest-resolution archives for reconstructing oceanic conditions and historical changes in climate prior to the instrumental era,” Mobasher said. “This not only helps us understand our environment’s response to changes that occurred hundreds to thousands of years in the past, but it also enables us to make inferences for how Earth will handle present and future conditions.”

Mobasher came to FSU as a master’s student in 2022 to conduct research in the Tropical Paleo-Dynamics Group under the mentorship of Alyssa Atwood, associate professor in the Department of Earth, Ocean, and Atmospheric Science, after earning her bachelor’s in environmental science and geoscience at the University of Wisconsin-Green Bay. In 2024, Mobasher earned a National Science Foundation Graduate Research Fellowship to support her graduate work, and she’s continuing to conduct her doctoral research under Atwood.

“Neda’s master’s research provided important insight into the limitations of a new tool used in coral-based temperature reconstructions,” Atwood said. “Her work shows that a particular technique that works well in many tropical regions performs poorly when applied to the Galápagos Islands, a unique region of the eastern tropical Pacific critical for understanding ENSO. Rigorous tests like Neda has performed are necessary to develop accurate reconstructions of past climate change.”

Mobasher uses a wide variety of tools and techniques, including radiocarbon dating and scanning electron microscopy, to generate the coral records used to create a well-rounded picture of ENSO’s history. She also uses facilities in the NSF-funded, FSU-headquartered National High Magnetic Field Laboratory and the FSU Department of Chemistry and Biochemistry and leverages her work’s collaborative nature to forge multi-institutional partnerships.

“For radiocarbon dating, I travel to the University of California, Irvine, for its accelerator mass spectrometer, which is probably the size of a residential two-car garage,” Mobasher said. “I’ve also done uranium-thorium dating at the University of Minnesota Twin Cities, and the travel is a wonderful way to connect with senior scientists and peers. I wouldn’t have the privilege of running all these different kinds of tests, both at home and away, if it weren’t for Dr. Atwood.”

Atwood’s guidance has inspired Mobasher to pay it forward. She presently mentors three undergraduates annually as part of FSU’s Undergraduate Research Opportunity Program and is one of only two FSU students to earn a 2026 Graduate Student Undergraduate Research Mentor Award.

“Building research projects with undergrads and seeing them grow has been an influential part of my FSU journey, and it’s made me want to focus on teaching after defending my dissertation,” Mobasher said. “Chemical oceanography is such a broad, critical field, and I want to be part of training the next generation of scientists making valuable contributions to our understanding of how Earth functions.” 

Kendall Cooper is a two-time FSU alumna who earned a master's degree in media and communication studies with a certification in project management in 2025 and a bachelor’s degree in media and communication studies with a double major in editing, writing and media in 2023.