Caltech Researcher to Explain How Ocean ‘Snowfall’ Shapes the Climate at Free Seaside Talk

Somewhere between the sunlit surface of the ocean and the dark floor thousands of feet below, a quiet snowfall is always underway. Not ice crystals, but clumps of dead algae, bacterial mucus, and organic debris — marine snow, the ocean’s slow-motion conveyor belt for carbon.

On Tuesday, a Caltech researcher studying how that process works will explain it to anyone willing to walk down a staircase to a seaside lab in Corona del Mar.

Dieter Baumgartner, a postdoctoral fellow in geobiology in Caltech’s Division of Geological and Planetary Sciences in Pasadena, will present “The Marine Snowball Event—How Encounters Shape Carbon Export” on July 21 at Kerckhoff Marine Laboratory as part of Science Tuesdays, a free weekly summer series of public talks, hands-on activities, and tours now in its second year, according to the Caltech events calendar. The talk runs from 4:30 p.m. to 6:00 p.m. Admission is free and all ages are welcome.

Baumgartner earned his doctorate at ETH Zürich in Switzerland, where he studied bacterial physiology in the lab of Prof. Roman Stocker. At Caltech, he is developing a new model system to study the biophysical mechanisms behind marine snow formation, according to his research website. His work sits at the intersection of microbiology, biophysics, and fluid flow — fields that together are reshaping how scientists understand the ocean’s role in cycling carbon.

The research has practical significance. The ocean’s biological carbon pump — the process by which marine snow and other sinking particles carry carbon from the surface to the deep — is a major factor in regulating atmospheric carbon dioxide levels. Baumgartner’s talk will address how encounters among particles and organisms during that sinking journey shape the amount of carbon the ocean ultimately sequesters, according to the event listing.

Baumgartner has co-authored research published in Nature Communications, Nature Microbiology, the Proceedings of the National Academy of Sciences, and Physical Review Letters, according to his publications page.

Science Tuesdays launched in 2025 and returned this summer for a second season, according to a report by Pasadena Now. The series runs every Tuesday through the summer, with a different speaker each week followed by an activity. The lab also offers tours upon request, and visitors are welcome to walk through the facility on their own, according to the Kerckhoff Marine Laboratory website.

Kerckhoff Marine Laboratory, operated by Caltech since 1929, sits at the edge of China Cove in the Corona del Mar section of Newport Beach. The facility is one of the oldest marine laboratories on the West Coast. Victoria Orphan, the James Irvine Professor of Environmental Science and Geobiology at Caltech, directs the lab. Stephen Ranson manages day-to-day operations, according to the KML website.

Science Tuesdays: “The Marine Snowball Event—How Encounters Shape Carbon Export” takes place Tuesday, July 21, 2026, from 4:30 p.m. to 6:00 p.m. at Kerckhoff Marine Laboratory, 101 Dahlia Avenue, Corona del Mar. Admission is free and open to all ages; RSVPs are available through Eventbrite at https://www.eventbrite.com/e/science-tuesdays-at-kml-tickets-1395407705009. There is no parking at the lab; visitors should park along Ocean Boulevard and walk down the staircase to China Cove, then turn right and continue to the facility. For more information, call 949-675-2159 or visit kml.caltech.edu.

The next Science Tuesday, on July 28: Madison Dunitz, a graduate student in geobiology at Caltech, presenting “Geo-Engineering with Microbes,” according to the Caltech events calendar. Separately, the lab hosts a Saturday evening “Science & Sunsets” event on July 25 featuring Dr. Shana Goffredi, chair of the Biology Department at Occidental College, speaking on deep-sea animal microbiomes.