A study finds that the Greenland ice sheet is losing an average of 30 million tons of ice per hour due to the climate crisis, which is 20% more than previously thought.
Some scientists fear that this additional source of fresh water flowing into the North Atlantic could mean a collapse of ocean currents called the Atlantic Southern Circulation (AMOC) is closer to being triggered, with serious consequences for humanity, writes the Guardian. who publishes the study.
There has been significant ice loss from Greenland for decades due to global warming. Techniques used to date, such as measuring the height of the ice sheet or its weight using gravity data, are effective in determining losses that end up in the ocean and raise sea levels. However, they cannot explain the retreat of glaciers that already lie mostly below sea level in the narrow fjords around the island.
Scientists analyzed satellite photos to determine the final positions of Greenland’s many glaciers each month from 1985 to 2022. This showed large and widespread shortening, and in total it totals in the trillions of tons of ice lost.
“The changes around Greenland are enormous and are happening everywhere: almost all the glaciers have retreated in recent decades,” said Dr Chad Greene, from NASA’s Jet Propulsion Laboratory in the US, who led the research. “It stands to reason that if you dump fresh water into the North Atlantic Ocean, you will definitely get a weakening of the AMOC, although I don’t have an idea of how large the weakening is.”
Amoc was already known to be at its weakest point in 1,600 years, and in 2021 researchers spotted warning signs of a turning point. A recent study suggested that collapse could occur as early as 2025, in a worst-case scenario. Scientists also believe that a significant portion of the Greenland ice sheet itself is close to a critical point of irreversible melting, with ice equivalent to 1-2 meters of sea level rise likely already expected.
The study, published in the journal Nature, used artificial intelligence techniques to map more than 235,000 glacier terminus locations over 38 years, at a resolution of 120 meters. This showed that the Greenland Ice Sheet has lost an area of around 5,000 square kilometers of ice at its margins since 1985, equivalent to a trillion tonnes of ice.
The most recent update from a project that compiles all other Greenland ice measurements found that 221 billion tons of ice have been lost every year since 2003. The new study adds another 43 billion tons per year, bringing the total loss at around 30 million tonnes per hour on average.