Glaciers distinct from the Greenland and Antarctic ice sheets are shrinking rapidly, altering regional hydrology 1 , raising global sea-level 2 and elevating natural hazards 3 . Yet, due to the scarcity of constrained mass loss observations, glacier evolution during the satellite era is only known as a geographic and temporal patchwork 4,5 . Here we reveal the accelerated, albeit contrasted, patterns of glacier mass loss during the early twenty-first century. By leveraging largely untapped satellite archives, we chart surface elevation changes at a high spatiotemporal resolution over all of Earth's glaciers. We extensively validate our estimates against independent, high-precision measurements and present the first globally complete and consistent estimate of glacier mass change. We show that, during 2000-2019, glaciers lost 267 ± 16 Gt yr -1 , equivalent to 21 ± 3% of observed sea-level rise 6 . We identify a mass loss acceleration of 48 ± 16 Gt yr -1 per decade, explaining 6-19% of the observed acceleration of sea-level rise. Particularly, thinning rates of glaciers outside ice sheet peripheries doubled over the last two decades. Glaciers presently lose more mass, and at similar or larger accelerated rates, than the Greenland or Antarctic ice sheets taken separately [7][8][9] . Uncovering the patterns of mass change in many regions, we find contrasted glacier fluctuations that agree with decadal variability in precipitation and temperature. Those include a newly-identified North Atlantic anomaly of decelerated mass loss, a strongly accelerated loss from Northwestern American glaciers and the apparent end of the Karakoram anomaly of mass gain 10 . We anticipate our highly-resolved estimates to foster the understanding of drivers that govern the distribution of glacier change, and to extend our capabilities of predicting these changes at all scales. Predictions robustly benchmarked against observations are critically needed to design adaptive policies for the management of local water resources and cryospheric risks as well as for regional-to-global sea-level rise.About 200 million people live on land predicted to fall below the high-tide lines of rising sea levels by the end of the century 11 , while more than one billion could face water shortage and food insecurity within the next three decades 4 . Glaciers distinct from the ice sheets play a prominent role in these repercussions as the largest estimated contributor to twenty-first century sea-level rise after thermal expansion 2 , and as one of the most climate-sensitive constituents of the world's natural water towers 12,13 . Current glacier retreat temporarily mitigates water stress on populations reliant on ice reserves by increasing river runoff 1 , but this short-lived effect will eventually decline 14 . Understanding present-day and future glacier mass change is thus crucial to avoid water scarcity-induced socio-political instability 15 , to predict the alteration of coastal areas due to sea-level rise 4 , and to assess the impacts on ecosystems 16 as w...
[1] Changes in air temperature, precipitation, and, in some cases, glacial runoff affect the timing of river flow in watersheds of western Canada. We present a method to detect streamflow phase shifts in pluvial, nival, and glacial rivers. The Kendall-Theil robust lines yield monotonic trends in normalized sequent 5-day means of runoff in nine river basins of western Canada over the period . In comparison to trends in the timing of the date of annual peak flow and the center of volume, two other less robust metrics often used to infer streamflow timing changes, our approach reveals more detailed structure on the nature of these changes. For instance, our trend analyses reveal extension of the warm hydrological season in nival and glacial rivers of western Canada. This feature is marked by an earlier onset of the spring melt, decreases in summer streamflow, and a delay in the onset of enhanced autumn flows. Our method provides information on streamflow timing changes throughout the entire hydrological year, enhancing results from previous methods to assess climate change impacts on the hydrological cycle.
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