A recent study has uncovered that the Greenland ice cap is experiencing an average hourly loss of 30 million tonnes of ice due to the climate crisis, marking a 20% increase from previous estimates.

Concerns among scientists are growing, as this additional influx of freshwater into the north Atlantic raises fears of a potential triggering of the collapse of the Atlantic meridional overturning circulation (Amoc), with potentially severe consequences for humanity.

While significant ice loss from Greenland has been documented for decades due to global heating, current measurement techniques, such as assessing ice sheet height or weight through gravity data, effectively quantify losses that contribute to rising sea levels. However, these methods do not account for the retreat of glaciers predominantly located below sea level in the island's narrow fjords.

The study employed satellite photos to analyze the monthly end positions of Greenland's numerous glaciers from 1985 to 2022. The findings revealed extensive and widespread glacier shortening, amounting to a total loss of a trillion tonnes of ice during the examined period.

“The transformations occurring around Greenland are significant, and they're pervasive – nearly every glacier has undergone retreat over the past few decades,” explained Dr. Chad Greene, who led the research at NASA’s Jet Propulsion Laboratory in the US. “It logically follows that introducing freshwater into the North Atlantic Ocean would lead to a weakening of the Amoc, although the extent of this weakening is not intuitively clear to me.”

The Amoc was already identified as its weakest in 1,600 years, and in 2021, researchers observed warning signals indicating a potential tipping point. According to a recent study, the collapse could potentially occur as early as 2025 in the worst-case scenario. Scientists also believe a substantial portion of the Greenland ice sheet is nearing a tipping point of irreversible melting, equivalent to 1-2 meters of sea level rise, and this may already be anticipated.

Published in the journal Nature, the study utilized artificial intelligence techniques to map over 235,000 glacier end positions over a 38-year period, achieving a resolution of 120 meters. The findings demonstrated that the Greenland ice sheet had lost an area of approximately 5,000 square kilometers of ice at its peripheries since 1985, equivalent to a trillion tonnes of ice.

The most recent update from a comprehensive project compiling all measurements of Greenland’s ice revealed a loss of 221 billion tonnes of ice annually since 2003. The new study contributes an additional 43 billion tonnes per year, resulting in a total loss averaging about 30 million tonnes per hour.

Uncharted Threats: Greenland's Melting Ice Raises Concerns Over AMOC Collapse

The scientists expressed their worries, stating, “There is some concern that any small source of freshwater may serve as a ‘tipping point’ that could trigger a full-scale collapse of the AMOC, disrupting global weather patterns, ecosystems, and global food security. Yet freshwater from the glacier retreat of Greenland is not included in oceanographic models at present.” The introduction of less dense freshwater into the sea impedes the conventional process of heavier salty water sinking in the polar region, affecting the AMOC.

Professor Tim Lenton from the University of Exeter, UK, who was not involved in the study, voiced his apprehension, saying, “This additional freshwater input to the North Atlantic is a concern, particularly for the formation of deep water in the Labrador and Irminger Seas within the subpolar gyre, as other evidence suggests these are the regions most prone to being tipped into an ‘off,’ or collapsed state.”

“That would be like a partial AMOC collapse, but unfolding faster and having profound impacts on the UK, western Europe, parts of North America, and the Sahel region, where the West African monsoon could be severely disrupted,” he added. “Whether this previously unaccounted source is enough freshwater to make a difference depends on how close we are to that subpolar gyre tipping point. Recent models suggest it could be close already at the present level of global warming.”