Abstract
The large Juneau and Stikine icefields (Alaska) lost mass rapidly in the
second part of the 20th century. Laser altimetry, gravimetry and field
measurements suggest continuing mass loss in the early 21st century. However,
two recent studies based on time series of Shuttle Radar Topographic Mission (SRTM) and
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation
models (DEMs) indicate a slowdown in mass loss after 2000. Here, the
ASTER-based geodetic mass balances are recalculated carefully avoiding the
use of the SRTM DEM because of the unknown penetration depth of the C-band
radar 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), in
agreement with laser altimetry, confirming that mass losses are continuing at
unabated rates for both icefields. The SRTM DEM should be avoided or used
very cautiously to estimate glacier volume change, especially in the North
Hemisphere and over timescales of less than ∼ 20 years.
Citation
ID:
175173
Ref Key:
berthier2018thebrief