Scientists have identified a turning point around the year 2000, marking an intensification of El Niño’s impact on the reduction of sea ice surrounding Siberia.
Researchers have long been aware of a reciprocal relationship existing between the El Niño-Southern Oscillation (ENSO) phenomenon and the ice cover found in high latitudes. Nevertheless, this recent study uncovered that, commencing around the year 2000, swifter transitions between ENSO phases began exerting a more pronounced effect on ice melt across Russia’s northeast. These shifts result in warmer and moister atmospheric conditions in the area, leading to diminished ice cover during the autumn following an ENSO phase change.
The findings from this new investigation could prove beneficial for refining ice cover forecasts utilized by vessels navigating through this geographical section. Furthermore, they hold the potential to enhance scientific comprehension of the long-term fluctuations characterizing Earth’s climate system. “Sea ice can substantially influence Arctic climate and maritime safety,” noted co-author Zeng Wang from the Hong Kong University of Science and Technology.
El Niño is a climatic event defined by recurring variations in atmospheric pressure and sea surface temperature within the tropical Pacific Ocean over several years. These fluctuations possess the capacity to affect global weather patterns and climates, including the frequency of phenomena like hurricanes, tropical cyclones, and droughts.
In the new research, documented in the journal Science Advances, investigators examined how ENSO affects Arctic sea ice, focusing their attention specifically on the Laptev and East Siberian Seas, situated northeast of Russia. The team analyzed monthly datasets pertaining to sea surface temperature and sea ice concentration, gathered between 1979 and 2023, aiming to discern recurring patterns linking ENSO transitions with the subsequent year’s ice extent.
The outcomes demonstrated that exiting the El Niño phase precipitates the formation of cold surface water zones in the central and eastern Pacific near the tropics during the ensuing autumn. After 2000, the shift away from El Niño started to accelerate, a possibility attributed to interactions with the Pacific Decadal Oscillation, another long-term climate cycle influencing Pacific temperature variability.
These swift reversals caused the cool patches to become even colder. Subsequently, these frigid regions displaced a high-pressure system, known as the West-North Pacific Anticyclone (WNPAC), northward, directing it towards the Arctic. The northern displacement of the WNPAC subsequently fosters the development of a second anticyclone stationed over the Laptev and East Siberian Seas. Collectively, these interconnected mechanisms transport both heat and moisture from the northern Pacific into the Arctic, causing ice melt along their path.
The researchers found that prior to 2000, the connection between these cold areas and the western North Pacific region was not vigorous enough to significantly alter the Arctic ice extent.
The shifts observed since the year 2000 are attributable to the Earth’s intrinsic climatic cycles, rather than anthropogenic activities, the researchers stated. However, human-caused climate change “introduces greater uncertainty into how we forecast these multi-year ice variations,” commented Xiaojun Yuan from Columbia University’s Lamont-Doherty Earth Observatory, who was not involved in the study.
Climate change driven by human actions may supersede some of the natural trends evident in these extended oscillations, Yuan added.
In forthcoming work, Wang mentioned that the team plans to investigate the impact of anthropogenic climate change on the sea ice within this specific area.
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