Ancient Baffin Bay ice shelf buttressed three ice sheets, study finds

An observational study reports that a floating ice shelf more than a mile thick occupied Baffin Bay about 20,000 years ago and buttressed three large ice sheets in northern Canada and Greenland. Sonar mapping and sediment cores indicate that the shelf covered the bay and supported the Greenland Ice Sheet to the east, the Innuitian Ice Sheet to the north and the Laurentide Ice Sheet to the west. The researchers interpret the shelf’s disappearance over an estimated 500 to 1,000 years as having allowed glaciers on land to flow faster into the ocean, contributing to hundreds of feet of sea-level rise and helping establish modern coastlines. The study concerns the last glacial period and does not directly quantify the future response of Antarctic glaciers.

The evidence was gathered during a five-week research cruise in Baffin Bay, west of Greenland, that was initially intended to collect sediment cores for reconstructing what destabilized the Greenland Ice Sheet at the end of the last ice age. The scientists were not searching specifically for a large ice shelf. Instead, sonar mapping of the seafloor revealed clear features indicating that a vast floating ice shelf had once occupied the bay. Robert Hatfield, an associate professor of geology at the University of Florida and a co-author of the study, said the evidence extended more than a mile into the ocean. That implied a thickness at least half a mile greater than that of any previously known ice shelf in the Northern Hemisphere. The mapped scale showed that the reconstructed shelf had reached an exceptional size, with its extent comparable to some of the key ice shelves in Antarctica today.

Sediment cores collected across Baffin Bay provided the basis for reconstructing the shelf’s later history. Their evidence suggests that the floating ice disappeared over roughly 500 to 1,000 years. The researchers interpreted this loss as removing a buttressing effect that had restrained ice resting on land. Without that support, glaciers from the Greenland, Innuitian and Laurentide ice sheets could accelerate toward the ocean, where their melting contributed to sea-level rise. The study therefore links the disappearance of one extensive floating structure with the subsequent destabilization of three adjacent land-based ice sheets. The reconstruction is regional in scope: it documents a specific episode in Baffin Bay during the last glacial period rather than establishing a universal pattern or a direct forecast for present-day Antarctica.

The authors say the reconstructed size and scale of the Baffin Bay ice shelf were not previously known. Hatfield compared the relationship between an ice sheet and its floating support to a Gothic cathedral and its flying buttresses, explaining that ice shelves can slow the flow of ice on land into the ocean. He described the disappearance of a shelf comparable in scale to major Antarctic examples within centuries as an unexpected result of the research. Scientists who model past and present glaciers and ice shelves may use the new evidence to constrain those models, potentially improving predictions of how quickly grounded ice responds when buttressing is lost. The findings do not set a specific rate for Antarctic ice loss or provide a quantified projection of future sea-level rise; instead, they supply an observed past case in which the loss of an extensive ice shelf was followed by faster discharge from several neighboring ice sheets and higher sea levels.

Subject of Research: Evidence that a vast Baffin Bay ice shelf buttressed three ice sheets during the last glacial period

Article Title: How a massive ice shelf buttressed the last ice age’s glaciers — and what it could mean for Antarctica today

Article References: How a massive ice shelf buttressed the last ice age’s glaciers — and what it could mean for Antarctica today. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: Baffin Bay, ice shelf, ice sheets, Greenland, Laurentide Ice Sheet, Innuitian Ice Sheet, buttressing, sea-level rise, glacier dynamics, last glacial period, massive, shelf