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

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 km(2)) 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 km(2)(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.