Paper: The enigma of Oligocene climate and global surface temperature evolution
Featured image: Figure 1 from O’Brien et al. (2020). Paleogeographic reconstruction of the late Oligocene world, with continents and oceans in slightly different positions than today. Symbols indicate paleo-locations of ocean sediments that these scientists discuss in their paper, with stars indicating sites where they estimated Oligocene temperatures.
Authors: Charlotte L. O’Brien, Matthew Huber, Ellen Thomas, Mark Pagani, James R. Super, Leanne E. Elder, Pincelli M. Hull
We know that the amount of carbon dioxide in the atmosphere strongly affects climate –and temperature – on Earth. As carbon dioxide concentrations increase, so does average global temperature; this pattern is clear from direct historical measurements and ice core records going back hundreds of thousands of years. Nevertheless, it’s important to understand how this relationship operated in the past (for example, during times when there was less ice in the cold polar regions of the globe). A new study suggests that, millions of years in the past, the simple relationship between carbon dioxide and temperatures may not have been so clearcut.
Continue reading “Ancient ocean temperatures outline a puzzling period in Earth’s climate history”
Featured image: A coral colony from Maldives, Indian Ocean. Picture credit: Андрей Корман from Pixabay (Public domain)
Paper: Potential of reef building corals to study the past Indian monsoon rainfall variability
Author: Supriyo Chakraborty
Paleooceanographers have often used reef-building corals to study oceanic processes like the El Niño and Southern Oscillation, ocean circulation patterns, air–sea gas exchange, and the Indian Ocean dipole (a.k.a Indian Niño), among others. Yet how exactly do corals provide clues about the physical and chemical conditions of their environments? The answer lies in their skeletons.
Continue reading “Could corals help study the variability of past Indian monsoons?”
Featured Image: Ichthyoliths (microfossil fish teeth) from deep-sea sediment cores displaying the variety of tooth morphology. Photo courtesy of Elizabeth Sibert, lead author of the paper.
Paper: No state change in pelagic fish production and biodiversity during the Eocene–Oligocene transition
Authors: Elizabeth C. Sibert, Michelle E. Zill, Ella T Frigyik, Richard D. Norris
The seafloor at the bottom of the ocean records what is happening in the water above. Sediments capture silica from diatoms and phytoplankton, carbon from zooplankton poop and detrital marine snow, and teeth after dead fish sink. This last piece of evidence is particularly important: fossilized fish teeth or icthyoliths can help estimate past fish abundance and can show shifts in fish species or biodiversity in the ocean over time.
Continue reading “What do deep-sea sediment cores tell us about past fish populations?”