Asynchronous behavior of outlet glaciers feeding Godthåbsfjord (Nuup Kangerlua) and the triggering of Narsap Sermia's retreat in SW Greenland

Roman J. Motyka, Ryan Cassotto, Martin Truffer, Kristian K. Kjeldsen, Dirk van As, Niels J. Korsgaard, Mark Fahnestock, Ian Howat, Peter L. Langen, John Mortensen, Kunuk Lennert, Søren Rysgaard

Research output: Contribution to journalArticleResearchpeer-review

37 Citations (Scopus)

Abstract

We assess ice loss and velocity changes between 1985 and 2014 of three tidewater and five-land terminating glaciers in Godthåbsfjord (Nuup Kangerlua), Greenland. Glacier thinning accounted for 43.8 ± 0.2 km 3 of ice loss, equivalent to 0.10 mm eustatic sea-level rise. An additional 3.5 ± 0.3 km 3 was lost to the calving retreats of Kangiata Nunaata Sermia (KNS) and Narsap Sermia (NS), two tidewater glaciers that exhibited asynchronous behavior over the study period. KNS has retreated 22 km from its Little Ice Age (LIA) maximum (1761 AD), of which 0.8 km since 1985. KNS has stabilized in shallow water, but seasonally advects a 2 km long floating tongue. In contrast, NS began retreating from its LIA moraine in 2004-06 (0.6 km), re-stabilized, then retreated 3.3 km during 2010-14 into an over-deepened basin. Velocities at KNS ranged 5-6 km a -1, while at NS they increased from 1.5 to 5.5 km a -1 between 2004 and 2014. We present comprehensive analyses of glacier thinning, runoff, surface mass balance, ocean conditions, submarine melting, bed topography, ice mélange and conclude that the 2010-14 NS retreat was triggered by a combination of factors but primarily by an increase in submarine melting.

Original languageEnglish
Pages (from-to)288-308
Number of pages21
JournalJournal of Glaciology
Volume63
Issue number238
DOIs
Publication statusPublished - 1 Apr 2017

Keywords

  • glacier calving
  • glacier discharge
  • glacier mass balance
  • ice/atmosphere interactions
  • ice/ocean interactions
  • tidewater glaciers

Programme Area

  • Programme Area 5: Nature and Climate

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