Greenland’s Ice Cap Losing 30m Tonnes of Ice an Hour, Study Reveals
The Greenland ice cap is experiencing a rapid loss of ice due to the climate crisis, according to a recent study. The research shows that the ice cap is losing an average of 30 million tonnes of ice every hour, which is 20% more than previously estimated. This alarming rate of ice loss has raised concerns among scientists about the potential collapse of the Atlantic meridional overturning circulation (Amoc), a crucial ocean current system.
For decades, scientists have been monitoring the major ice loss from Greenland caused by global heating. Previous techniques used to measure the ice loss, such as gravity data and measuring the height of the ice sheet, were effective in determining the losses that contribute to rising sea levels. However, these methods failed to account for the retreat of glaciers that lie below sea level in the narrow fjords surrounding Greenland.
To address this limitation, researchers analyzed satellite photos from 1985 to 2022 to track the end position of Greenland’s glaciers on a monthly basis. The analysis revealed significant and widespread shortening of glaciers, resulting in a total loss of one trillion tonnes of ice. Dr. Chad Greene from NASA’s Jet Propulsion Laboratory, who led the research, emphasized the magnitude of the changes, stating that almost every glacier in Greenland has retreated over the past few decades.
The implications of this ice loss extend beyond rising sea levels. The influx of freshwater from Greenland into the North Atlantic Ocean weakens the Amoc, which is already at its weakest point in 1,600 years. Some scientists believe that this additional freshwater could push the Amoc closer to a tipping point, potentially leading to its collapse. The consequences of such an event would be severe, affecting global weather patterns, ecosystems, and food security.
Moreover, scientists warn that a significant portion of the Greenland ice sheet itself is nearing a tipping point of irreversible melting. This would result in a rise in sea levels equivalent to 1-2 meters. The study, published in the journal Nature, utilized artificial intelligence techniques to map over 235,000 glacier end positions over a 38-year period. The analysis revealed that the Greenland ice sheet has lost approximately 5,000 square kilometers of ice at its margins since 1985, equivalent to a trillion tonnes of ice.
The findings of this study have added another layer of concern to the ongoing climate crisis. The most recent update from a project that collects various measurements of Greenland’s ice indicates that 221 billion tonnes of ice have been lost annually since 2003. The new study adds an additional 43 billion tonnes per year, resulting in an average loss of 30 million tonnes per hour.
The impact of this ice loss on the Atlantic meridional overturning circulation is a cause for worry. Freshwater from Greenland’s glacier retreat is not currently included in oceanographic models, but its introduction into the sea disrupts the usual process of denser saltwater sinking in the polar region and driving the Amoc. Professor Tim Lenton from the University of Exeter explains that this additional freshwater input to the North Atlantic could lead to the collapse of the subpolar gyre, which would have profound impacts on regions such as the UK, western Europe, parts of North America, and the Sahel region.
While some experts find reassurance in the steady pace of ice loss since the turn of the century, others emphasize the importance of accounting for this additional ice loss in calculating Earth’s energy imbalance. The energy required to melt one trillion tonnes of ice is significant and must be considered for precise energy balanced models.
The study also highlights the importance of monitoring Antarctic ice shelves. Another analysis conducted by Dr. Chad Greene and his colleagues in 2022 revealed that the total loss from Antarctic ice shelves since 1997 was doubled when accounting for the shrinking areal extent and thinning of the shelves.
In conclusion, the study’s findings shed light on the alarming rate at which Greenland’s ice cap is losing ice. The implications extend beyond rising sea levels, with concerns about the potential collapse of the Atlantic meridional overturning circulation and irreversible melting of the Greenland ice sheet. These findings emphasize the urgent need for global action to address the climate crisis and mitigate its devastating consequences.
