The Arctic is warming three to four times faster than the global average. But recent research suggests that a slowdown in major ocean currents could reduce projected warming in the Arctic by 2 degrees Celsius by the end of this century. For years, scientists have warned that unabated warming in the Arctic could have devastating consequences, threatening wildlife and ushering in an era of more frequent and extreme weather events. Amid concerns about such consequences, a study from UC Riverside offers limited relief.
A published study Proceedings of the National Academy of Sciences Examines the impact of the slowdown in the Atlantic Meridional Overturning Circulation (AMOC) on the Arctic climate. The AMOC is a current that carries heat from the tropics to higher latitudes.
While Arctic temperatures are expected to rise by 10 degrees Celsius by the end of the century, the study shows that Arctic temperatures will increase by only 8 degrees Celsius when the slowing AMOC current is taken into account.
AMOC’s role in heat dissipation
“The AMOC is a critically important component of our climate system because it moves heat around the globe,” said Yu-Chi Lee, a graduate student in UCR’s Department of Earth and Planetary Sciences and first author of the study. “We found that weakening reduces the amount of heat reaching the Arctic, which slows the rate of warming.”
Despite this potential benefit, the study highlights ongoing challenges for Arctic ecosystems. Polar bears face habitat loss as sea ice melts, making it harder to hunt and survive. Additionally, when ice melts, darker-colored clear water is released, which absorbs more sunlight and further accelerates warming through a process called the albedo effect.
While the slowdown could ease some of the warming in the Arctic, researchers warn it could also lead to other climate changes. One of the biggest concerns is the potential shift in the Intertropical Convergence Zone, the tropical rain belt. If this rain belt moves southward, regions dependent on rainfall may experience more frequent droughts, which could affect agriculture and water resources.
There are also misconceptions about the connection between sea ice and sea level rise. Melting sea ice does not directly cause sea level rise because the ice is already in the water, just as melting ice cubes in a glass will not cause the water to overflow. But land ice, such as glaciers, and the expansion of water when heated contribute to sea level rise. The slowdown in the AMOC is not the main cause of sea level rise, but it is bringing about other important changes in the climate system.
Complex climate interactions and an uncertain future
Wei Liu, an associate professor of climate change at UC Riverside and co-author of the paper, emphasized the complexity of AMOC’s role in global climate. “The slowing of the AMOC may provide temporary relief in the Arctic, but it’s not just good news,” Liu said. “The overall impact on ecosystems and weather, both in the Arctic and globally, could still be severe.”
The research team used a coupled climate model that combines interactions between the ocean, atmosphere, land and sea ice. The researchers isolated the impact of the AMOC by running two simulations: One allowed the AMOC to slow down under the influence of increasing greenhouse gases, and the other kept it artificially strong by extracting fresh water from the North Atlantic to increase salinity.
“Our simulations allowed us to clearly see how future Arctic warming is related to the slowing of the AMOC,” Lee said. “While the slowdown reduces warming by several degrees, the overall impact on Arctic ecosystems and the global climate system remains severe.”
Lee also emphasized that the slowdown started relatively recently, and there is still debate among scientists about how long it has been going on and whether it will continue.
“Direct in situ observations of the strength of the AMOC began around 2004, so it is a relatively short time period to draw long-term conclusions,” he said. “But there are studies that suggest it could collapse by the end of this century, and that could have huge consequences.”
Looking ahead, Lee remains focused on the big picture. “While a slowdown in the AMOC may provide some short-term benefits, its broader impact shows us that even small changes in ocean circulation can cause ripple effects across the planet. Climate change is far from a problem for one region,” he said. “The future of the Arctic and the world depends on how we respond today.”
Source: Port Altele
