Greenland losing 30m tonnes of ice an hour

A recent study has revealed that the Greenland ice cap is experiencing an average ice loss of 30 million tonnes per hour due to the impact of the climate crisis, surpassing previous estimates by 20%. This increased rate of freshwater entering the north Atlantic has raised concerns among scientists, who fear that it could bring the Atlantic meridional overturning circulation (Amoc) closer to collapse, with potentially severe consequences for humanity.

The significant ice loss from Greenland, attributed to global heating, has been documented for decades. Traditional methods, such as measuring the ice sheet’s height or weight through gravity data, effectively capture losses contributing to rising sea levels. However, they fail to consider the retreat of glaciers situated predominantly below sea level in the narrow fjords surrounding the island. In this study, scientists analyzed satellite photos to track the monthly end positions of Greenland’s numerous glaciers from 1985 to 2022. The findings revealed extensive and widespread shortening, amounting to a total loss of one trillion tonnes of ice.

There are significant and widespread changes occurring around Greenland, with almost every glacier retreating over the past few decades. Dumping freshwater into the north Atlantic, as observed in the study, is expected to weaken the Atlantic meridional overturning circulation (Amoc), although the extent of this weakening remains uncertain.

The Amoc, already identified as the weakest in 1,600 years, exhibited warning signs of a tipping point in 2021, with a potential collapse predicted as early as 2025 in the worst-case scenario. Scientists also believe a substantial portion of the Greenland ice sheet is on the brink of irreversible melting, contributing to an anticipated sea level rise of 1-2 meters.

Published in the journal Nature, the study employed artificial intelligence techniques to map over 235,000 glacier end positions with a resolution of 120 meters over a 38-year period. Results showed that the Greenland ice sheet had lost approximately 5,000 square kilometers of ice at its margins since 1985, equivalent to a trillion tonnes of ice.

Scientists expressed concern about the potential impact of this additional freshwater on the Amoc, noting that even small sources could act as tipping points leading to a full-scale collapse. Current oceanographic models do not incorporate freshwater from Greenland’s glacier retreat. The influx of less dense freshwater into the sea disrupts the normal sinking of heavier, salty water in the polar region, affecting the Amoc.

The concerns about freshwater input into the north Atlantic, particularly in the Labrador and Irminger Seas, are heavy. These regions are considered prone to tipping into a collapsed state, potentially impacting the UK, western Europe, parts of North America, and the Sahel region. The west African monsoon in the Sahel could face severe disruption, with implications for global weather patterns, ecosystems, and food security.