UW’s Clementz Co-Writes Paper Connecting Volcanic Eruptions, Global Cooling

Mark Clementz, a professor in the University of Wyoming Department of Geology and Geophysics, and colleagues have produced a compelling study that shows that an increase in volcanic activity in the Andes in the Late Miocene Epoch likely resulted in a cooling of the Earth between 5.4 million and 7 million years ago.

The volcanic activity produced a biological boom in the Southern Ocean, which led to a drawdown of atmospheric carbon dioxide that resulted in global cooling, Clementz and co-authors concluded. Their findings are in a new article, titled “Andean volcanism, ocean fertilization, marine ecosystem turnover, and global cooling in the Late Miocene,” published this week in the journal Nature Communications Earth and Environment.

The Late Miocene, Clementz says, “represents a pivotal transition in Earth’s climate system, marking the shift toward the modern climatic regime and the establishment of many of today’s floral and faunal assemblages. Identifying the mechanisms that drove this transition is critical, particularly for understanding how Earth systems may respond to ongoing and future climate change.”

The research was funded by the National Science Foundation and involves an international collaboration among Clementz; Barbara Carrapa, Priscilla Martinez and Kaustubh Thirumalai, all from the University of Arizona; Nicolás Cosentino, Universidad de Buenos Aires; Pedro DiNezio, University of Colorado-Boulder; Pam Vervoort, University of Birmingham; Jordan Abell, Lehigh University; Dominik Hülse, University of Bremen; and Carolina Gutstein, from Universidad Santo Tomás.

By combining multi-proxy data from field and laboratory research with multiple computer modeling simulations using known and extrapolated data, the study shows a potential link between sustained, large-scale volcanism in the Altiplano-Puna volcanic complex, the largest active silicic magma system on Earth, and global climatic and ecological change.

Volcanic ash is known to contain important nutrients, including phosphorus, iron and silicon. A significant increase in volcanic activity in the Andes peaking between 4 million and 8 million years ago, therefore, likely delivered a significant pulse of nutrients -- especially iron -- to the Southern Ocean.

This increase in nutrients, in turn, would have stimulated an increase in diversity and abundance of marine life -- notably microscopic, single-celled algae called diatoms, which are not only one of the largest producers of chlorophyll in the world, pulling carbon dioxide from the atmosphere, but also essential to ocean food chains.

This corresponds to available fossil records, which show big changes in marine vertebrate populations during this period. Cetaceans, the order of marine mammals to which whales belong, went through significant evolutionary shifts, including the development of larger bodies, greater diversification and long-distance migratory behaviors.

Whales sink to the ocean floor when they die, sequestering carbon. But they also produce large volumes of carbon-rich feces, which may have been responsible for producing toxic algal blooms that killed off other marine life on a mass scale, greatly increasing the carbon stored in the ocean. This, together with the photosynthetic activity of diatoms and other concurrent events, would have contributed significantly to a drawdown of atmospheric carbon dioxide. And, indeed, models confirm that carbon dioxide levels in the atmosphere fell by about 10-15 parts per million, subsequent to these events preserved in the geological record, resulting in global cooling within the warmer climate of the Miocene.

“This work improves our understanding of how natural processes can regulate Earth’s climate, which is directly relevant to anticipating future climate change and its impacts on society,” Clementz says. “By identifying links between volcanism, ocean productivity and carbon dioxide drawdown, it provides insight into mechanisms that can influence global climate over long time scales.”

Clementz hopes his research will help inform science-based decision-making related to natural resources, climate resilience and environmental change. He is excited that this study positions Wyoming at the forefront of both cutting-edge Earth system science and, through its extensive fossil record from earlier periods, situates Wyoming’s paleontological resources in a broader, global context of ecosystem change through time.

The full article is available here: www.nature.com/articles/s43247-026-03457-4. To learn more about the history of the ideas behind the research on Carrapa’s blog, go to https://communities.springernature.com/posts/andean-volcanism-ocean-fertilization-marine-ecosystem-turnover-and-global-cooling-in-the-late-miocene-eb21fc68-b275-4df4-9f34-8b03d417a375.