A recent study calls into question existing theories about the significant transitions that have occurred throughout the Earth’s ice ages. This research offers new perspectives on the ocean’s influence on climate during the Mid-Pleistocene Transition, a puzzling period of climatic changes that started approximately one million years ago.
A newly published research article in Science questions prevailing theories on the origins of a crucial transition during the Earth’s ice ages. Conducted by a global team of scholars from the Woods Hole Oceanographic Institution (WHOI), the Lamont-Doherty Earth Observatory, the Scripps Institution of Oceanography, and Cardiff University, this study reveals fresh perspectives on the ocean’s role in climate during the Mid-Pleistocene Transition, a mysterious period of climate cycle alterations that began around one million years ago.
Various theories exist regarding the Mid-Pleistocene Transition, with one key theory suggesting that it coincided with a notable reduction in the Atlantic Meridional Overturning Circulation (AMOC). However, the new research indicates that the deep ocean plays an equally important but more complex role.
By analyzing climate records from the last 1.2 million years, the research team reconstructed essential deep ocean characteristics that are vital for comprehending ocean flow and carbon storage. “The deep ocean is vast, especially when compared to its ability to hold carbon dioxide (CO2) versus the atmosphere,” stated lead author Dr. Sophie Hines, an Assistant Scientist at WHOI. “Even a slight alteration in ocean circulation could have major implications for global climate.”
The researchers examined sediment core samples gathered during the International Ocean Discovery Program (IODP) Expedition 361 near Cape Town, South Africa. By investigating carbon and oxygen from fossils of tiny single-celled organisms known as foraminifera, along with neodymium isotopes, the team discovered key details regarding shifts in deep ocean temperature and salinity, as well as the mixing processes of waters from the northern and southern hemispheres.
Dr. Sidney Hemming, the Arthur D. Storke Memorial Professor of Earth and Environmental Sciences at the Lamont-Doherty Earth Observatory and co-chief scientist of the expedition, mentioned, “Importantly, we demonstrate that changes in various deep ocean characteristics do not always occur together. With our well-resolved multi-proxy record that includes transitional periods, we find that the intensification of ice ages was primarily driven by changes around Antarctica.”
The research indicates that the expansion of the Antarctic Ice Sheet enhanced the ocean’s ability to sequester carbon, resulting in decreased atmospheric CO2 levels, cooler climates, and extended ice age cycles.
Dr. Hines further noted, “Our findings illuminate the complex relationships between ocean dynamics and climate change, highlighting the critical role of the Southern Ocean in understanding the climate history of our planet.”
Recent investigations emphasize the pressing need to address human-induced climate change, particularly in relation to the decrease in AMOC strength. As the Southern Ocean continues to warm rapidly, it is essential to comprehend its dynamics. The Southern Ocean is crucial in regulating global climate patterns, and any changes could have significant impacts on ecosystems and weather systems globally.
