Collaborative Research: Seasonal and century-scale climatic and ocean response to deglacial Mississippi River outflow due to Laurentide meltwater

Boston College, Chestnut Hill MA

Investigators

Abstract

The last deglaciation occurred from approximately 20,000 to 11,700 years ago when rising atmospheric temperatures caused Earth’s main ice sheets to melt. Vast amounts of water from the vanishing Laurentide Ice Sheet flowed through the Mississippi River system into the marine environment. The mixing of fresh meltwater with saline ocean water on such a mass scale triggered abrupt changes in regional climate, ocean circulation, and ecosystems. This project seeks to understand how environmental systems responded to these freshwater inputs on seasonal and century timescales. By improving our understanding of the short- and long-term effects of past ice sheet melt, the research will help scientists and the public anticipate the potential consequences of modern ice sheet melting and freshwater input on marine ecosystems. The project will support student research and training and engage broad audiences through public-facing data visualizations and educational outreach. This research will develop a refined and detailed understanding of climatic and oceanographic changes across Earth’s last deglaciation due to the meltwater released from the Laurentide Ice Sheet. The project will generate new high-resolution reconstructions of ocean-atmospheric and biogeochemical variability from strategically located marine sediment cores (already collected) and integrate these with existing paleoclimate data. The cores derive from the Garrison Basin offshore Texas, where deposited sediment captures meltwater pulses with minimal influence from the Loop Current. The team will focus on characterizing the spatial extent, timing, and frequency of freshwater intrusions into the marine environment via the Mississippi River outflow and evaluate their influence on ocean stratification and regional climate. Specific emphasis will be placed on resolving both seasonal and century-scale dynamics by combining stable isotope, trace metal, and microfossil analyses with climate model simulations of the last deglaciation. The results will clarify critical feedbacks between freshwater forcing, ocean circulation, and marine ecosystem structure during periods of rapid ice sheet retreat, offering valuable analogs for ongoing and future global shifts. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.