Ubiquitous acceleration in Greenland Ice Sheet calving from 1985 to 2022

• 成果类型: Article
• 署名作者: Greene, Chad A.; Gardner, Alex S.; Wood, Michael; Cuzzone, Joshua K.
• 署名单位: California Institute of Technology; National Aeronautics & Space Administration (NASA); NASA Jet Propulsion Laboratory (JPL); Moss Landing Marine Laboratories; California State University System; San Jose State University; University of California System; University of California Los Angeles
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5196
• DOI: 10.1038/s41586-023-06863-2
• 发表日期: 2024-01-18
• 关键词: mass-balance; southwestern greenland; terminus position; ocean; glaciers; retreat; SYSTEM; variability; RESOLUTION; ELEMENTS

摘要

Nearly every glacier in Greenland has thinned or retreated over the past few decades1-4, leading to glacier acceleration, increased rates of sea-level rise and climate impacts around the globe5-9. To understand how calving-front retreat has affected the ice-mass balance of Greenland, we combine 236,328 manually derived and AI-derived observations of glacier terminus positions collected from 1985 to 2022 and generate a 120-m-resolution mask defining the ice-sheet extent every month for nearly four decades. Here we show that, since 1985, the Greenland Ice Sheet (GrIS) has lost 5,091 +/- 72 km2 of area, corresponding to 1,034 +/- 120 Gt of ice lost to retreat. Our results indicate that, by neglecting calving-front retreat, current consensus estimates of ice-sheet mass balance4,9 have underestimated recent mass loss from Greenland by as much as 20%. The mass loss we report has had minimal direct impact on global sea level but is sufficient to affect ocean circulation and the distribution of heat energy around the globe10-12. On seasonal timescales, Greenland loses 193 +/- 25 km2 (63 +/- 6 Gt) of ice to retreat each year from a maximum extent in May to a minimum between September and October. We find that multidecadal retreat is highly correlated with the magnitude of seasonal advance and retreat of each glacier, meaning that terminus-position variability on seasonal timescales can serve as an indicator of glacier sensitivity to longer-term climate change. Analysis of more than 236,000 observations of glacier terminus positions shows that accelerated calving reduced the ice area of Greenland by about 5,000 km2 since 1985, producing over 1,000 Gt of freshwater that could influence ocean salinity and circulation.