The Greenland ice sheet has now been shrinking at an unprecedented rate for several decades. According to a study by the journal, Nature, Greenland’s ice cap is currently losing 30 million tons of ice per hour. Scientists have warned this could cause ocean currents to collapse and have a significant impact on the entire planet.
The authors of the study, published on January 17, examined 236,000 satellite images of 207 glaciers in Greenland between 1985 and 2022. The researchers manually marked the changes at the edges of glaciers and then automated the process using a trained AI algorithm which then allowed them to measure the changes over the years studied and to make future predictions.
Overall, the study shows that trillions of tons of ice have already been lost from Greenland’s ice cover and the loss of 30 million tons of ice per hour is 20% higher than previously estimated. So far, 5,000 sq km of ice cover is believed to have disappeared since 1985 due to climatic changes. The melting ice has contributed to 20% of the total rise in sea levels since 2002 with these increased levels putting at risk the lives of many living in coastal areas and small islands.
Fig.1. Mass of Greenland ice sheet relative to mass in 2022, billion tons
Source: The Guardian
The rising sea levels, however, are not the only concern for scientists. Researchers warn that fresh water entering the North Atlantic due to melting ice may eventually collapse the ocean currents associated with the Atlantic Meridional Overturning Circulation (AMOC) which circulates water within the Atlantic Ocean from the north to the south and back again in a long cycle. If this does happen, it is believed the consequences will be massive for humanity. Recent studies have shown that the ocean currents are already at their weakest point in 1600 years and, in the worst-case scenario, may reach a tipping point in 2025. Greenland’s ice sheet, in contrast, is already believed to be at its tipping point of irreversible melting, and a sea level rise of 1 to 2 meters can be expected.
NASA’s Jet Propulsion Laboratory researcher, Dr Chad Greene, who led the research said:
“The changes around Greenland are tremendous and they’re happening everywhere – almost every glacier has retreated over the past few decades. It makes sense that if you dump fresh water on to the north Atlantic Ocean, then you certainly get a weakening of the AMOC, though I don’t have an intuition for how much weakening.”
A full-scale failure of the AMOC currents could trigger global weather disasters, disrupting weather patterns which, in turn, threatens to cause global food insecurity. AMOC currents include the Gulf Stream that takes tropical water up to the US and to Europe where it contributes to the comparatively warm temperatures there.
The shrinking Greenland ice sheet has been somewhat ignored by researchers as the main focus has been on the rising sea levels. A glaciologist at the IBS Center for Climate Physics at Pusan National University in South Korea, Vincent Verjans, noted after reviewing the study that this publication will help scientists to comprehensively view the entire ecosystem and better understand the patterns of global warming.
