In a groundbreaking study, Dr. Luz María Mejía and her team at MARUM – Center for Marine Environmental Sciences at the University of Bremen have uncovered new insights into the climate of the Miocene epoch, a period spanning from 5 to 23 million years ago. Their research, which focuses on the past 16 million years, suggests that previous assumptions about extreme warmth in high northern latitudes during this era may need reevaluation. This revelation is particularly significant as it draws parallels with current CO₂ levels, which are projected to reach between 400 and 600 ppm, according to the latest IPCC report.
Dr. Mejía’s team utilized clumped isotopes in fossil coccoliths—calcite plates produced by marine plankton known as coccolithophores—as a key indicator. These organisms, which thrive in the sunlit surface layer of the ocean, record isotopic signatures that depend on the water temperature during their lifetime. By measuring the degree of isotope clumping, researchers can reconstruct past water temperatures, offering a window into the climate conditions of millions of years ago.
Revolutionizing Climate Reconstruction Techniques
The study’s innovative approach involved developing a semi-automatic filtering machine combined with centrifugation to extract large quantities of coccoliths from sediment samples. This method, refined at the Eidgenössischen Technische Hochschule (ETH) Zurich, allowed the team to isolate coccoliths without contamination from other organisms or abiotic calcite.
The results were surprising. “Perhaps the most widely used and accepted temperature indicator, especially for the Miocene, is the alkenone unsaturation index,” Dr. Mejía explained. This index is based on organic fossil molecules also produced by coccolithophores and has been instrumental in forming the paradigm that high latitudes were extremely warm during past warm periods, such as the Miocene.
“Coccolith clumped isotopes suggest that the North Atlantic was 9 degrees Celsius cooler than previously proposed,” Dr. Mejía noted, challenging the established paradigm of extreme warmth in high northern latitudes.
Implications for Future Climate Predictions
This new evidence suggests that temperatures during the Miocene may not have been as extreme as once thought, which could have implications for how we predict future climate scenarios. The study emphasizes the need for continual reassessment of climate reconstruction indicators to accurately interpret both trends and absolute temperature values.
Dr. Mejía cautions that this study is just the beginning. “We need to test more,” she stated, indicating that future research will involve investigating fossil coccoliths from various regions and latitudes. This work is part of the broader research efforts within the “Ocean Floor” Excellence Cluster, which seeks to understand the role of the ocean and the seafloor in the Earth’s system.
MARUM’s Commitment to Marine Science
MARUM is dedicated to producing fundamental scientific knowledge about the ocean’s role in the Earth’s system. By examining the interactions of geological, physical, biological, and chemical processes, MARUM aims to understand their impact on climate and the global carbon cycle. The center is committed to unbiased research and public dissemination of its findings, in line with the United Nations’ sustainability goals.
Through its collaboration with industrial partners, MARUM ensures that its research supports the protection of the marine environment. The center’s commitment to sharing quality-assured scientific data underscores its role as a leader in marine environmental sciences.
As Dr. Mejía and her team continue their investigations, the scientific community eagerly anticipates further insights that could reshape our understanding of Earth’s climatic history and inform future climate models.
