The Link Between Whales In The Andes & Climate Change

Construction work in Chile’s Atacama Desert uncovered an extraordinary fossil site known as Cerro Ballena, or “Whale Hill,” containing over 40 well-preserved marine mammal fossils dating back 6 to 9 million years. These remains include whales, porpoises, and other marine species that perished rapidly within a confined area. The discovery has provided a unique window into the late Miocene epoch, a period marked by significant climatic and geological shifts, particularly the rise of the Andes mountains. Researchers from the University of Arizona have linked the mass die-off at Cerro Ballena to intense volcanic activity in the Andes during the late Miocene. Volcanic eruptions released vast quantities of ash rich in nutrients like iron, phosphorus, and silicon into the Southern Ocean. This nutrient influx triggered explosive growth of diatoms—microscopic algae that form the base of many marine food webs—leading to both an increase in whale size due to abundant food and the occurrence of toxic algal blooms that proved fatal to many marine mammals in the region. The study highlights a complex interplay between volcanism, ocean ecosystems, and global climate. While volcanoes are typically associated with warming due to carbon dioxide emissions, the nutrient-rich ash stimulated carbon sequestration by diatoms, which absorbed large amounts of CO2 from the atmosphere. This process contributed to a global cooling trend during the late Miocene, demonstrating an underappreciated mechanism by which volcanic activity can influence climate beyond direct greenhouse gas emissions. Barbara Carrapa, lead author and geosciences professor at the University of Arizona, emphasised the importance of this multidisciplinary research, which combined climate modelling, geochemistry, paleobiology, and geological data. The findings suggest that volcanic ash played a critical role in reshaping marine ecosystems and driving climatic changes that had far-reaching effects beyond South America. This research not only sheds light on past climate dynamics but also enhances understanding of how natural processes can regulate atmospheric carbon over geological timescales. Co-author Kaustubh Thirumalai noted that the late Miocene was a pivotal period for mammalian evolution and global climate, marked by a cooling trend and declining atmospheric CO2 levels whose causes were previously unclear. The study’s insights into volcanic nutrient inputs and their cascading ecological impacts provide a plausible explanation for these changes, offering valuable context for interpreting Earth’s climatic history and the evolution of marine life during this transformative epoch.