Glacier mass and area changes on the Kenai Peninsula, Alaska, 1986–2016

Abstract

Glacier mass loss in Alaska has implications for global sea level rise, fresh water input into the Gulf of Alaska and terrestrial fresh water resources. We map all glaciers (>4000 km2) on the Kenai Peninsula, south central Alaska, for the years 1986, 1995, 2005 and 2016, using satellite images. Changes in surface elevation and volume are determined by differencing a digital elevation model (DEM) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer stereo images in 2005 from the Interferometric Synthetic Aperture Radar DEM of 2014. The glacier area shrunk by 543 ± 123 km2 (12 ± 3%) between 1986 and 2016. The region-wide mass-balance rate between 2005 and 2014 was −0.94 ± 0.12 m w.e. a−1 (−3.84 ± 0.50 Gt a−1), which is almost twice as negative than found for earlier periods in previous studies indicating an acceleration in glacier mass loss in this region. Area-averaged mass changes were most negative for lake-terminating glaciers (−1.37 ± 0.13 m w.e. a−1), followed by land-terminating glaciers (−1.02 ± 0.13 m w.e. a−1) and tidewater glaciers (−0.45 ± 0.14 m w.e. a−1). Unambiguous attribution of the observed acceleration in mass loss over the last decades is hampered by the scarcity of observational data, especially at high elevation, and by large interannual variability.

Accelerated retreat of coastal glaciers in the Western Prince William Sound, Alaska

“…The majority of coastal glaciers in the study area are retreating, with rapid mass loss occurring from the mid-2000s to 2018. These findings are consistent with reported glacier mass loss in Alaska (Arendt et al 2006;Molnia 2008;Arendt, Walsh, and Harrison 2009; Berthier et al 2010;Yang et al 2020) and western North America (Menounos et al 2019). O'Neel et al (2019 measured an area loss of 1.5 km 2 for Wolverine Glacier from 1971 to 2018, which is similar to the findings in this study (1.4 km 2 over 1975-2018), and attributed mass loss to warmer summer temperatures.…”

“…Here, measured glaciers in the Sargent Icefield and Spencer-Blackstone Ice subregions lost ~8 percent of their total area from 1986 to 2018. The lower percentage of area loss compared to Yang et al (2020) is attributed to the exclusion of glaciers smaller than 10 km 2 . Other studies in Alaska (Meier and Dyurgerov 2002), the Northern Alps (Paul et al 2004), and the Chinese Tien Shan (K. Li et al 2011;Y.…”

“…Both studies estimated the highest rates of area loss occurring from 2006 to 2018 at Wolverine Glacier. Yang et al (2020) compiled new inventories for glaciers in the Kenai Peninsula, including the Sargent Icefield and Spencer-Blackstone Ice Complex, and found a significant loss in total glacier area (~12 percent) from 1986 to 2016. Here, measured glaciers in the Sargent Icefield and Spencer-Blackstone Ice subregions lost ~8 percent of their total area from 1986 to 2018.…”

Glacier Surface Speed Variations on the Kenai Peninsula, Alaska, 2014–2019

“…Part of the differences can be attributed to differences in glacier size (and associated thickness). Although on average half as steep as the 1,431 land‐terminating glaciers, the 18 lake‐, and 11 marine‐terminating glaciers are almost two orders of magnitude larger (Yang et al., 2020) and thus considerably thicker (Farinotti et al., 2019). The greater flow speeds of the tidewater glaciers compared to the other two types can be attributed to additional mass losses due to frontal ablation (iceberg calving and submarine melt) at the calving front (most likely exceeding those of the lake‐terminating glaciers considerably; Truffer and Motyka (2016)) and larger mass turnover due to greater snow accumulation and steeper mass balance gradients close to the coast where these glaciers are located compared to western inland locations (E. W. Burgess et al., 2013).…”

“…The 5 m IFSAR DEM in 2014 (http://viewer.nationalmap.gov/basic/ access date: December 2018) is currently the best available DEM for the study region with an accuracy of 0.53 ± 1.38 m (mean ± 1 standard deviation) relative to ICESat (Yang et al., 2020). We resampled the DEM to 30 m resolution, and used it as topography reference for image coregistration, geocoding, and topographical correction.…”