The last glacial maximum, a time when ice sheets reached their greatest extent and global temperatures were at their coldest, a period marked by extreme cold and extensive ice coverage, stands as one of Earth’s most significant climatic events. It provides a unique opportunity to understand how ice, temperature, and atmospheric conditions interact. A new study led by Professor Hong Wang and his team from Beijing Normal University and the Institutes of Earth Environment and Tibitan Pleateau Reserach of the Chinese Academy of Sciences delves into how the Laurentide Ice Sheet, the largest of its time, responded to these climatic shifts. Published in npj Climate and Atmospheric Science, the research offers insightful findings about the cold and warm phases change of this traditionally-known cold era and their wide-reaching effects on the planet.
The study describes the last glacial maximum as a period lasting thousands of years. During this time, the Laurentide Ice Sheet underwent major changes, advancing and retreating vast distances as winter and summer temperatures fluctuated and atmospheric wind patterns shifted. Wang and his colleagues synthesized precise radiocarbon dating results, techniques used to determine the age of ancient short-lived organic materials by measuring radioactive isotopes to create a detailed timeline of these events, revealing important insights into the behavior of the ice sheet and the release of meltwater into the North Atlantic Ocean.
“Our findings reveal a fascinating pattern: an initial period of intense cold gave way to relatively warmer summers as the last glacial maximum progressed,” explains Professor Wang. The research highlights how the temperature near the ice sheet edges increased noticeably during this time, showing how sensitive the climate was to even minor changes in sunlight and atmospheric conditions.
The retreat of the Laurentide Ice Sheet, during late Last Glacial Maximum periods, triggered significant warmer effects across the planet. The meltwater it released from the Illinois River Valley (IRV) and Mississippi River Valley (MRV) contributed only slightly to rising sea levels, but its timing was critical in influencing ocean circulation patterns, via shift of westerly wind axis, like the Atlantic ocean circulation, a powerful system of ocean currents that redistributes heat and influences climate patterns, a system that distributes heat and affects weather globally. This connection illustrates how local changes in ice sheet behavior can impact weather and precipitation patterns far away.
The study also sheds light on how the ice sheet’s southern expansion during an exceptionally cold phase marked the peak of the last glacial maximum, with substantial retreats happening afterward. Professor Wang notes, “This dynamic underscores how ice sheets are constantly changing and are deeply interconnected with the atmospheric and oceanic systems they interact with.”
Professor Wang and colleagues used a model to simulate how the Laurentide Ice Sheet affected the Earth’s crust and explored how westerly winds, prevailing winds that flow from the west to the east in temperate regions shifted as the ice receded. These changes influenced North American weather patterns, bringing warmth and moisture during periods of retreat and reinforcing cold, dry conditions during advances. This perspective emphasizes the critical role of atmospheric feedback in shaping glacial history with impact globally.
Professor Wang’s team’s discoveries not only enhance our understanding of past climate systems but also provide important tools for predicting how current climate change might unfold. The relationship between ice sheets, wind patterns, and global temperatures and precipitation serves as a stark reminder of the potential consequences of modern ice melt.
Journal Reference
Wang, H., An, Z., Zhang, X., Shu, P., He, F., Liu, W., Lu, H., Ming, G., Liu, L., Zhou, W. “Westerly and Laurentide Ice Sheet Fluctuations During the Last Glacial Maximum.” npj Climate and Atmospheric Science, 2024. DOI: https://doi.org/10.1038/s41612-024-00760-9
