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Abstract A mass-balance model using upper-air meteorological data for input was calibrated with surface mass balance measured mainly during 1977–78 at 67 sites on Columbia Glacier, Alaska, between 135 and 2645 m a.s.l. Root-mean-square error, model vs measured, is 1.0 m w.e. a −1 , with r 2 = 0.88. A remarkable result of the analysis was that both precipitation and the factor in the positive degree-day model used to estimate surface ablation were constant with altitude. The model was applied to reconstruct glacier-wide components of surface mass balance over 1948–2007. Surface ablation, 4 km 3 ice eq. a −1 (ice equivalent), has changed little throughout the period. From 1948 until about 1981, when drastic retreat began, the surface mass balance was positive but changes in glacier geometry were small, so the positive balance was offset by calving, ∼0.9 km 3 ice eq. a −1 . During retreat, volume loss of the glacier accounted for 92% of the iceberg production. Calving increased to ∼4.3 km 3 ice eq. a −1 from 1982 to 1995, and after that until 2007 to ∼8.0 km 3 ice eq. a −1 , which was about twice the loss by surface ablation, whereas prior to retreat it was only about a quarter as much. Calving is calculated as the difference between glacier-wide surface mass balance and geodetically determined volume change.
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Increasing rate of 21st century volume loss of the Patagonian Icefields measured from proglacial river discharge
Abstract The Northern and Southern Patagonian Icefields are rapidly losing volume, with current volume loss rates greater than 20 km3a−1. However, details of the spatial and temporal distribution of their volume loss remain uncertain. We evaluate the rate of 21st-century glacier volume loss using the hydrological balance of four glacierised Patagonian river basins. We isolate the streamflow contribution from changes in ice volume and evaluate whether the rate of volume loss has decreased, increased, or remained constant. Out of 11 glacierised sub-basins, seven exhibit significant increases in the rate of ice volume loss, with a 2006–2019 time integrated anomaly in the rate of glacier volume loss of 135 ± 50 km3. This anomaly in the rate of glacier-volume-loss is spatially heterogeneous, varying from a 7.06 ± 1.69 m a−1increase in ice loss to a 3.18 ± 1.48 m a−1decrease in ice loss. Greatest increases in the rate of ice loss are found in the early spring and late summer, suggesting a prolonging of the melt season. Our results highlight increasing, and in some cases accelerating, rates of volume loss of Patagonia's lake-terminating glaciers, with a 2006–2019 anomaly in the rate of glacier volume loss contributing an additional 0.027 ± 0.01 mm a−1of global mean sea-level rise.
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- PAR ID:
- 10480388
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Journal Name:
- Journal of Glaciology
- Volume:
- 69
- Issue:
- 277
- ISSN:
- 0022-1430
- Page Range / eLocation ID:
- 1187 to 1202
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1017/jog.2023.9
