How a massive ice shelf buttressed the last ice age's glaciers—and what it could mean for Antarctica today
About 20,000 years ago, an enormous, floating ice shelf more than a mile (1.6 kilometers) thick helped lock in three of the largest ice sheets in northern Canada and Greenland. When that ice shelf disappeared, it helped unlock part of these ice sheets, which contributed to hundreds of feet of sea level rise, establishing modern coastlines as we know them.
Around 20,000 years ago, a gigantic floating ice shelf exceeding 1.6 kilometers in thickness played a crucial role in stabilizing three major ice sheets in northern Canada and Greenland. The sudden disappearance of this ice shelf triggered a chain reaction, causing parts of these ice sheets to flow into the ocean, resulting in hundreds of feet of sea level rise and the reshaping of modern coastlines.
This groundbreaking discovery comes from a new study that unearthed evidence of an ancient ice shelf in Baffin Bay, located west of Greenland, whose immense size and scale were unknown until now.
The authors of the study, Robert Hatfield from the University of Florida and his colleagues at the University of North Carolina Wilmington, Columbia University, and other institutions, published their findings in Nature Geoscience. The team's initial objective was to collect sediment cores to understand what caused the Greenland Ice Sheet to destabilize at the end of the last ice age. However, their exploration uncovered a remarkable revelation when they employed sonar mapping to survey the seafloor.
The unexpected find was a colossal ice shelf, occupying the entire Bay and acting as a protective barrier, restraining the margins of three ice sheets: the Greenland Ice Sheet to the east, the Innuitian Ice Sheet to the north, and the Laurentide Ice Sheet to the west. The researchers were astounded to discover that this ancient ice shelf extended more than a mile deep into the ocean, which is at least half a mile thicker than any previously known ice shelf in the Northern Hemisphere.
The catastrophic collapse of this ice shelf, spanning approximately 500 to 1,000 years, enabled the massive glaciers on land to accelerate their flow into the sea, melt, and consequently raise sea levels. This revelation poses a significant concern for Antarctica's massive ice sheets, as scientists now have a new data point to consider when predicting the speed at which these glaciers might melt and contribute to sea-level rise.
The study also highlights the importance of unexpected findings in uncovering new insights into Earth's past and potentially revolutionizing our understanding of modern ice sheets and their impact on global sea levels.
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