Researchers say runoff from Greenland’s rapidly melting ice sheet could seriously disrupt the currents in the Atlantic Ocean that regulate global climate. But a new study suggests that fresh water will not trigger a complete and irreversible collapse of circulation as some research predicts.
By 2100, Greenland’s meltwater could cause an additional 10% to 20% reduction in the strength of the Atlantic Meridional Overturning Circulation (AMOC), on top of its weakening. Many scientists are already expecting Researchers found that for this vast system of streams.
Previous research suggests the AMOC moves heat from the tropics toward the Northern Hemisphere and cold water back south toward Antarctica. Is at its weakest in more than 1,000 years Due to melting Arctic ice and rising ocean temperatures. Models show that circulation will continue to weaken for decades to comePotentially cold weather in northwestern Europe, additional sea level rise on the U.S. East Coast, and drought around the equator.
The AMOC rotates around the Atlantic Ocean, bringing warm water north along the ocean surface and cold water south along the ocean floor.
(Image credit: NASA/Goddard Space Flight Center Scientific Visualization Studio)
The new study finds that if we continue to cook the planet the Greenland ice sheet could cause the AMOC to weaken by 40% by 2300, well beyond the decline projected by some climate models. The authors said the results highlight the effects on the AMOC of the rising freshwater pulse off Greenland, which most climate models do not currently take into account.
“By the year 2100, yes, we have some, but the largest fraction is what we add later,” study co-authors Jost von Hardenberga professor in the department of environmental, land and infrastructure engineering at the Polytechnic University of Turin in Italy told Live Science.
Meltwater in the Arctic and Greenland slows the AMOC by preventing the formation of deep currents in the North Atlantic that carry circulation southward toward Antarctica. Deep currents form when masses of cold, salty water sink to the ocean floor, but fresh water input and rising water temperatures are preventing this move by diluting and warming surface waters.
While Arctic meltwater is commonly integrated into climate simulations, researchers have been slow to incorporate runoff from the Greenland ice sheet into models, partly because this runoff may not be as disruptive as Arctic meltwater on shorter time scales, von Hardenberg said.
Get the world’s hottest discoveries delivered straight to your inbox.
“To accurately represent Greenland’s melting, you need a specific, dynamic model for the Greenland ice sheet. This is good, but it requires a lot of resources to develop,” von Hardenberg said.
The Community Ice Sheet Model version 2 (CESM2) is one of the few available simulations of the Greenland ice sheet. For the study, von Hardenberg and his colleagues used a global climate model called EC-Earth3, which does not include the Greenland ice sheet. The team added ice sheet data from CESM2 to explore how it might influence the AMOC over the next few centuries. Adding the ice sheet separately allowed them to compare Greenland with and without AMOC weakening, clearly revealing the ice sheet’s influence on AMOC strength.
The results were published June 19 in the journal science advancementSuggest that the Greenland ice sheet will have a major impact on Atlantic Ocean currents, especially after 2100.
“It’s only after that date that Greenland really starts to melt rapidly,” von Hardenberg said. “If you go ahead in our simulations – we go to the year 2300 – that’s also when this meltwater becomes really extremely strong.”
yet the opposite Other studies that show the AMOC collapsing irreversibly Under climate change, in this model, circulation recovered after the team turned off or dialed down meltwater. greenhouse gas emissions. Both simulations that did not include the Greenland ice sheet and had similar results found a partial recovery when meltwater was turned off and a full recovery when greenhouse gas emissions were turned off.
Von Hardenberg said the recovery in the model shows that the AMOC is more stable than previously thought and does not go from an active state to a collapsed state so suddenly. “This is consistent with a strong weakening, but not a shutdown,” he said.
Overall, the findings suggest that it is important to include the Greenland ice sheet in climate models – von Hardenbergh and his colleagues plan to do so in the next version of the EC-Earth 3 model.
“This is really something that makes sense to better control the uncertainty of these future simulations,” von Hardenberg said. “If we have a larger set of models that include this component, we will be in a better position to try to answer the question, ‘How much of a reduction in AMOC do we expect under different scenarios?’”
Other experts agreed that integrating the Greenland ice sheet into climate models would increase the accuracy of AMOC predictions.
“What makes the study particularly interesting is that it directly tests a process that has often been highlighted as an important source of uncertainty in future AMOC projections,” said. Jonathan BakerA senior climate scientist at the Met Office in the UK, who was not involved in the study.
results are consistent previous research This shows that Greenland’s meltwater excess weakens the AMOC, but whether the system could collapse is still uncertain, Baker told Live Science in an email, given that the team only used one model. “Repeating these experiments in a broader range of models will be important to assess how robust the findings are,” he said.
Nicolas FoucaultAn assistant professor at the University of Georgia’s Skidaway Institute of Oceanography, who was not involved in the study, said he doesn’t think the use of a single model limits the analysis.
“I think this result is robust and I’m pleased to see the authors reach this conclusion in such a high-resolution and realistic coupled climate model,” Foucault told Live Science in an email. “This finding also agrees with other modeling results that require massive amounts of fresh water to drive irreversible changes in AMOC, far more fresh water than is available on Greenland.”
However, a third expert said the model used in the study is unrealistic, because its parameters make the AMOC more flexible than other models. Therefore, the study should be replicated in other models to draw unbiased conclusions.
“Although the reported experiment is interesting, its results are neither surprising nor should be interpreted as exemplary for the entire model ensemble.” Sybren Drizfouta professor of physical oceanography at the University of Southampton in the UK told Live Science in an email.
Von Hardenberg said researchers should further investigate the influence of the Greenland ice sheet on the AMOC. “It would be interesting to investigate this in the future [the AMOC’s recovery with Greenland meltwater] With other models, but it’s certainly encouraging to see it in a case,” he said.
Mehling, O., Bellomo, K., Fabiano, F., De Villiers, M., Petrini, M., Corti, S., and von Hardenberg, J. (2026). Limited influence of Greenland meltwater on the suddenness and reversibility of future changes in the Atlantic. science advancement, 12(25), eaed2633. https://doi.org/10.1126/sciadv.aed2633