A study published in Science challenges existing theories on the Mid-Pleistocene Transition, a period of significant climate change beginning around one million years ago. Led by a team of researchers from WHOI, Lamont-Doherty Earth Observatory, Scripps Institution of Oceanography, and Cardiff University, the research focuses on the ocean’s role in climate during this transition.
Theories have suggested that the weakening of the Atlantic Meridional Overturning Circulation (AMOC) played a key role in the transition, but the new findings suggest a more nuanced role for the deep ocean. The researchers reconstructed deep ocean properties crucial for understanding ocean flow and carbon sequestration capabilities. Dr. Sophie Hines, lead author of the study, emphasized the importance of the deep ocean in storing carbon dioxide and how even small changes in ocean circulation can impact global climate.
The team analyzed sediment core samples from the International Ocean Discovery Program Expedition 361 near Cape Town, South Africa. By studying carbon and oxygen from foraminifera fossils and neodymium isotopes, they uncovered details about changes in deep ocean temperature, salinity, and mixing histories of waters from both hemispheres. Dr. Sidney Hemming, co-chief scientist on the expedition, highlighted the importance of understanding how shifts in deep ocean properties are not always coincident, with ice age intensification influenced primarily by changes around Antarctica.
The expansion of the Antarctic Ice Sheet is suggested to have enhanced the ocean’s ability to store carbon, leading to lower atmospheric CO2 levels, colder climates, and extended ice age cycles. Dr. Hines emphasized the intricate interplay between ocean dynamics and climate change, particularly in the Southern Ocean, underscoring its significance in understanding the planet’s climate history.
Recent studies have underscored the urgency of anthropogenic climate change, especially in relation to reductions in the AMOC. As the Southern Ocean continues to warm rapidly, understanding its dynamics is crucial. The Southern Ocean plays a critical role in regulating global climate patterns, and any changes could have significant impacts on ecosystems and weather systems worldwide. The study highlights the importance of understanding the Southern Ocean’s role in determining global climate dynamics.
