DataSheet1_Quantifying Geodetic Mass Balance of the Northern and Southern Patagonian Icefields Since 1976.docx

Southern Andean glaciers contribute substantially to global sea-level rise. Unfortunately, mass balance estimates prior to 2000 are limited, hindering our understanding of the evolution of glacier mass changes over time. Elevation changes over 1976/1979 to 2000 derived from historical KH-9 Hexagon imagery and NASADEM provide the basis for geodetic mass balance estimates for subsets of the Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI), extending current mass balance observations by ∼20 years. Geodetic mass balances were −0.63 ± 0.03 m w.e. yr−1 for 63% of the NPI and −0.33 ± 0.05 m w.e. yr−1 for 52% of the SPI glacierized areas for this historical period. We also extend previous estimates temporally by 25% using NASADEM and ASTER elevation trends for the period 2000 to 2020, and find geodetic mass balances of −0.86 ± 0.03 m w.e. yr−1 for 100% of the NPI and −1.23 ± 0.04 m w.e. yr−1 for 97% of the SPI glacierized areas. 2000–2020 aggregations for the same areas represented in the 1976/1979 to 2000 estimates are −0.78 ± 0.03 m w.e. yr−1 in the NPI and −0.80 ± 0.04 m w.e. yr−1 on the SPI. The significant difference in SPI geodetic mass balance in the modern period for 100% vs. 52% of the glacierized area suggests subsampling leads to significant biases in regional mass balance estimates. When we compare the same areas in each time period, the results highlight an acceleration of ice loss by a factor of 1.2 on the NPI and 2.4 on the SPI in the 21st century as compared to the 1976/1979 to 2000 period. While lake-terminating glaciers show the most significant increase in mass loss rate from 1976/1979–2000 to 2000–2020, mass balance trends are highly variable within glaciers of all terminus environments, which suggests that individual glacier sensitivity to climate change is dependent on a multitude of morphological and climatological factors.

南美洲安第斯山脉的冰川对全球海平面上升的贡献显著。遗憾的是，2000年之前的物质平衡估算有限，这阻碍了我们理解冰川质量随时间演化的过程。1976/1979年至2000年间，基于历史KH-9 Hexagon影像和NASADEM数据得出的高程变化，为北帕塔哥尼亚冰原（NPI）和南帕塔哥尼亚冰原（SPI）部分区域的地测量质量平衡估算提供了基础，从而将当前的质量平衡观测数据扩展了约20年。对于NPI的63%和SPI冰川覆盖区域的52%，该历史时期的地测量质量平衡分别为−0.63 ± 0.03 m w.e. yr−1和−0.33 ± 0.05 m w.e. yr−1。我们利用NASADEM和ASTER的高程趋势，将之前估算的时间范围扩展了25%，并对2000年至2020年间的数据进行了分析，发现NPI和SPI冰川覆盖区域的100%和97%的地测量质量平衡分别为−0.86 ± 0.03 m w.e. yr−1和−1.23 ± 0.04 m w.e. yr−1。与1976/1979年至2000年期间的估算值相比，2000年至2020年同一区域的汇总数据在NPI上为−0.78 ± 0.03 m w.e. yr−1，在SPI上为−0.80 ± 0.04 m w.e. yr−1。SPI在当代时期100%冰川覆盖区域与52%区域的地测量质量平衡的显著差异表明，子样本选择会导致区域质量平衡估算出现显著偏差。当我们对比每个时间段相同区域时，结果突显了21世纪NPI和SPI冰损失的加速，与1976/1979年至2000年期间相比，损失速率分别增加了1.2倍和2.4倍。尽管湖泊终结冰川在1976/1979年至2000年至2000年至2020年间质量损失速率增加最为显著，但所有终冰川环境中冰川的质量平衡趋势都高度多变，这表明单个冰川对气候变化的敏感性依赖于多种形态和气候因素。