New research led by the University of California, Riverside, suggests that a slowdown in a significant ocean current may help reduce Arctic warming projections by up to 2 degrees Celsius by the century’s end. The study was published in Proceedings of the National Academy of Sciences, investigating how a slowing Atlantic Meridional Overturning Circulation (AMOC) could affect the rate of warming in the Arctic, a region currently warming at a rate three to four times faster than the global average.

Impact of AMOC on Arctic Temperatures

The AMOC, a crucial part of Earth’s climate system, transports heat from tropical regions to higher latitudes. According to  the study, a weakening AMOC could mean less heat reaching the Arctic, thereby slowing the region’s warming. Without this factor, Arctic temperatures are projected to rise by up to 10 degrees Celsius by the century’s end; factoring in the AMOC, this rise may be limited to around 8 degrees.

Challenges for Arctic Ecosystems Despite Slower Warming

While a reduced temperature increase might offer some relief, Arctic ecosystems still face considerable challenges. Sea ice continues to melt, posing a threat to polar bears and other wildlife dependent on ice-covered habitats for survival. With ice disappearing, open water absorbs more sunlight, intensifying the warming process—a phenomenon known as the albedo effect. Wei Liu, associate professor of climate change at UC Riverside and co-author of the study, cautioned that while the AMOC slowdown could slow Arctic warming, the consequences are complex. “This is not simply a good-news story,” he remarked. “The broader impact on ecosystems and weather patterns may still be profound.”

Potential Global Impacts of AMOC Slowdown

The study also warns of possible climate disruptions beyond the Arctic. For instance, a slower AMOC may shift the Intertropical Convergence Zone (ITCZ), a tropical rain belt, southward. Such a shift could increase droughts in areas reliant on the ITCZ’s rainfall for agriculture and water supplies. Additionally, the study notes that while melting sea ice does not directly impact sea levels, other factors like melting land ice and the thermal expansion of warming ocean waters do contribute to rising sea levels.

Future Uncertainty and Climate Complexity

The research team used a climate model integrating ocean, atmosphere, land, and sea ice interactions, isolating the AMOC’s effect by conducting simulations under different scenarios. While this provided insights, the researchers acknowledge ongoing uncertainties about the AMOC’s long-term behaviour. Direct AMOC measurements have only been available since 2004, limiting data on its historical trends and future trajectory. “There’s still debate about whether the slowdown will continue or if a total collapse might happen by century’s end,” Lee noted.

Despite the temporary relief a weaker AMOC might offer, Lee emphasised the importance of a global perspective. “Even small shifts in ocean circulation can lead to ripple effects across the planet,” she said. “The future of the Arctic—and our world—depends on the actions we take now to address climate change.”