The Arctic region is heating up at a rate that is three to four times faster than the global average. Nevertheless, new findings indicate that a slowdown in a vital ocean current may lessen the anticipated warming in the Arctic by as much as 2 degrees Celsius by the close of the century.
The Arctic region is heating up at a rate that is three to four times faster than the global average. Nevertheless, new findings indicate that a slowdown in a vital ocean current may lessen the anticipated warming in the Arctic by as much as 2 degrees Celsius by the close of the century.
For many years, researchers have warned that unchecked warming in the Arctic could lead to severe repercussions, jeopardizing wildlife and bringing about more frequent and extreme weather events. In response to these concerns, a study led by UC Riverside provides some limited hope.
The research, published in the Proceedings of the National Academy of Sciences, focused on how the slowing of the Atlantic Meridional Overturning Circulation (AMOC) could impact the climate in the Arctic. The AMOC is responsible for transporting heat from the tropics to higher latitudes.
While Arctic temperatures are expected to increase by 10 degrees Celsius by the century’s end, the research demonstrates that accounting for the slowing AMOC results in only an 8 degrees Celsius rise in temperatures.
“The AMOC plays a crucial role in our climate system as it distributes heat globally,” explained Yu-Chi Lee, a graduate student in Earth and Planetary Sciences at UCR and the study’s lead author. “We discovered that its weakening leads to less heat reaching the Arctic, thereby reducing the warming rate.”
Despite this potential advantage, the study raises ongoing worries about Arctic ecosystems. The melting sea ice threatens polar bears’ habitats, making it increasingly challenging for them to hunt and survive. Additionally, as ice melts away, it reveals darker water, which absorbs more sunlight and accelerates warming through a process called the albedo effect.
Although the AMOC’s slowdown might slightly decrease Arctic warming, researchers warn that it may lead to other climate disturbances. One major concern is the possible southward shift of the Intertropical Convergence Zone, which is a tropical rainbelt. A movement of this rainbelt could result in more frequent droughts in regions that rely on its rainfall, impacting agriculture and water resources.
There is also some misunderstanding surrounding the relationship between melting sea ice and rising sea levels. It’s important to note that melting sea ice does not directly contribute to sea level rise as it is already floating, similar to how ice cubes that melt in a glass do not overflow the glass. In contrast, land ice like glaciers and the thermal expansion of water as it heats up do contribute to rising sea levels. While the AMOC slowdown isn’t a primary driver of sea level rise, it does bring about other significant climatic changes.
Wei Liu, an associate professor of climate change at UC Riverside and a co-author of the study, stressed the complexity of the AMOC’s role in the global climate. “The slowdown of the AMOC might provide some momentary relief in the Arctic, but it is not entirely a positive scenario,” Liu noted. “The broader effects on ecosystems and weather patterns, both in the Arctic and worldwide, could still be serious.”
The research team employed a coupled climate model to combine the interactions between ocean, atmosphere, land, and sea ice. They isolated the AMOC’s effects by conducting two simulations: one allowed the AMOC to weaken due to rising greenhouse gas levels, while the other artificially bolstered its strength by removing fresh water from the North Atlantic to increase its salinity.
“Our simulations give a clear picture of how much future Arctic warming is related to the AMOC’s slowdown,” Lee clarified. “Even though this weakening leads to a slight reduction in warming, the implications for Arctic ecosystems and the global climate system remain significant.”
Lee also pointed out that the slowdown began relatively recently, and there is still some debate among scientists regarding the duration of this trend and whether it will persist.
“Direct observations of the AMOC’s strength began around 2004, making it a relatively brief period from which to draw long-term conclusions,” she said. “However, some studies hint that it could collapse by the end of this century, which would have enormous consequences.”
Looking forward, Lee remains concerned about the bigger picture. “While the AMOC’s slowdown may offer some short-term gains, its wider effects reveal that even minor changes in ocean circulation can create far-reaching impacts globally. Climate change is not just a local issue,” she remarked. “The future of the Arctic—and the planet—relies on the actions we take today.”
