A frequent ice-free Arctic is likely to occur before the mid-21st century

• Published in: npj Climate and Atmospheric Science
• Main Authors: Zili Shen, Wen Zhou, Jinxiao Li, Johnny C. L. Chan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2023
• Subjects: Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Arctic; Climate change; Global warming; Sea ice
• Online Access: https://doi.org/10.1038/s41612-023-00431-1; https://doaj.org/article/a51f0006c3f644de8f2fd66d59dd4fbf

Abstract Although the trend of sea-ice extent under global warming has been studied extensively in recent years, most climate models have failed to capture the recent rapid change in the Arctic environment, which has brought into question the reliability of climate model projections of sea ice and suggested a potential shift in Arctic climate dynamics. Here, based on the results of a time-variant emergent constraint method with a weighting scheme, we show that an ice-free Arctic might occur earlier (by at least 5 ~ 10 years) than previously estimated. In other words, Arctic ice will likely disappear before the 2050 s. The observationally constrained date for an ice-free Arctic in September under fossil-fuel-based development (i.e., Shared Socioeconomic Pathway (SSP) 5–8.5) scenarios yields a central estimate of 2050–2054 with a 66% confidence range (equivalent to the IPCC’s ‘likely’ range) of 2037–2066, while an ice-free Arctic will likely occur for another 20 years and 11 years under ambitious mitigation scenarios (i.e., SSP2-4.5) and SSP3-7.0. An ice-free Arctic is unlikely to occur under the sustainable development scenario (i.e., SSP1-2.6). Looking forward, this time-variant emergent constraint may also help detect tipping points in the climate system. Our findings provide useful information to help policy makers cope with climate change.