Scientists have identified a tipping point that amplifies El Niño’s impact on Arctic sea ice loss.
Researchers have known for years about the feedback loop linking El Niño Southern Oscillation (ENSO) and high-latitude sea ice. However, in a new study, researchers found that starting around 2000, the transition between ENSO phases became faster and had a stronger impact on ice loss in northeastern Russia. These changes lead to warmer and wetter weather in the region, reducing sea ice extent in the fall after the transition.
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ENSO is a climate phenomenon that involves multi-year fluctuations in pressure and sea surface temperature in the tropical Pacific Ocean. These fluctuations can affect climate and weather patterns around the world, including the frequency of hurricanes, tropical cyclones, and droughts.
In a new study published January 14 in the journal Science Advances, researchers investigated how ENSO affects sea ice in the Arctic, focusing specifically on the Laptev Sea and East Siberian Sea in northeastern Russia. The researchers scrutinized monthly data on sea surface temperature and sea ice density collected from 1979 to 2023 and found patterns between the evolution of ENSO and the following year’s sea ice coverage.
The results showed that the transition from the El Niño period led to the formation of cold surface waters in the near-tropical central and eastern Pacific Ocean the following fall. After 2000, the transition from El Niño began to accelerate. This is likely due to interactions with the Pacific Decadal Oscillation, another long-term climate cycle that influences Pacific temperatures.
These rapid transitions caused cold regions to become even colder. These cold regions then pushed an anticyclone known as the Western North Pacific High (WNPAC) north toward the North Pole. Pushing WNPAC northward creates another anticyclone over the Laptev Sea and East Siberian Sea. These connected processes work together to pull heat and moisture from the North Pacific Ocean into the Arctic, melting ice along the way.
Before 2000, the link between cold regions and WNPAC was not strong enough to influence Arctic sea ice extent, the researchers found.
The changes that have occurred since 2000 are due to natural cycles in the Earth’s climate, not human activity, the researchers said. But anthropogenic climate change “brings great uncertainty to how we predict ice changes over decades,” said Xiaojun Yuan, an ocean physicist at Columbia University’s Lamont-Doherty Earth Observatory who was not involved in the study.
Human-induced climate change could reverse some of the natural patterns observed in these long-term changes, Yuan told Live Science.
In future studies, the research team plans to investigate the effects of anthropogenic climate change on sea ice in the region, Wang said.
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