Home / Science / North American Ice Sheets, Not Antarctica, Fueled Sea Level Rise After Last Ice Age
North American Ice Sheets, Not Antarctica, Fueled Sea Level Rise After Last Ice Age
11 Oct
Summary
- Majority of sea level rise 9,000-7,000 years ago came from North American ice sheet melt
- Newly discovered sediment records in Mississippi Delta provide high-resolution data
- Findings require "radical reworking" of ice melt history during this critical period
According to a study published in 2025, the majority of global sea level rise between 9,000 and 7,000 years ago was driven by the melting of ice sheets in North America, not Antarctica as scientists had long believed. The research, led by a team from Tulane University, overturns decades-old assumptions about the sources of meltwater that flooded the oceans as the planet warmed at the end of the last Ice Age.
The key evidence comes from deeply buried marsh sediments discovered off the coast of New Orleans by Tulane geologist Lael Vetter. By radiocarbon dating these sediment layers, the researchers were able to chart sea level changes over the past 10,000 years with unprecedented detail. An ex-Tulane PhD student, Udita Mukherjee, then matched this high-resolution Mississippi Delta record with data from Europe and Southeast Asia, revealing a clear global trend: the pace of sea level rise varied significantly across different locations, indicating the Northern Hemisphere was the primary contributor of meltwater.
Computer simulations modeling how the Earth's crust reacts to ice melt further supported this conclusion. The models suggested that North American ice sheets were responsible for approximately 14 meters, or 46 feet, of sea level rise during that 2,000-year period - four to ten meters more than previous estimates and at least three times greater than the contribution from Antarctica.
"This requires a radical reworking of the history of ice melting during this critical period," said Tulane Professor Torbjörn Törnqvist, a co-author of the study. "The amount of freshwater that entered the North Atlantic Ocean was much larger than previously believed, with a variety of implications."
For instance, that massive influx of freshwater could have disrupted the Atlantic Meridional Overturning Circulation, a critical ocean current system that transports heat from the equator to high latitudes. Sudden cooling events like the one around 8,200 years ago have long been linked to disruptions in this circulation, and the new evidence suggests the North American ice sheets were the primary driver of those climatic shocks.
