Brief communication: Unabated wastage of the Juneau and Stikine icefields (southeast Alaska) in the early 21st century

摘要

The large Juneau and Stikine icefields (Alaska) lost mass rapidly in thesecond part of the 20th century. Laser altimetry, gravimetry and fieldmeasurements suggest continuing mass loss in the early 21st century. However,two recent studies based on time series of Shuttle Radar Topographic Mission (SRTM) andAdvanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevationmodels (DEMs) indicate a slowdown in mass loss after 2000. Here, theASTER-based geodetic mass balances are recalculated carefully avoiding theuse of the SRTM DEM because of the unknown penetration depth of the C-bandradar signal. We find strongly negative mass balances from 2000 to 2016(−0.68 ± 0.15 m w.e. a−1 for the Juneau Icefield and−0.83 ± 0.12 m w.e. a−1 for the Stikine Icefield), inagreement with laser altimetry, confirming that mass losses are continuing atunabated rates for both icefields. The SRTM DEM should be avoided or usedvery cautiously to estimate glacier volume change, especially in the NorthHemisphere and over timescales of less than  ∼  20 years.