The nonlinear and complex behavior of glacier dynamic processes (e.g., surging and ice calving) presents major challenges for future estimates of runoff and sea-level change.
Because direct observations are temporally limited, reconstructions of past fluctuations from glaciers that undergo dynamic advance and/or retreat are valuable.
This study presents a detailed record of dynamic Langjökull outlet glacier fluctuations through the past 300 years, constructed from annually laminated sediment archives in Hvítárvatn, a large proglacial lake in Iceland’s central highlands. We demonstrate a novel combination of geophysical survey techniques (cm-scale multibeam bathymetric mapping and high-resolution seismic profiling) and multiple sediment cores taken from targeted locations to accurately constrain glacier fluctuations at unprecedented temporal resolution.
The authors were able to track the behavior of both Langjökull’s lake-terminating outlet glaciers during their occupation of Hvítárvatn and show that while Norðurjökull remained relatively stable, Suðurjökull’s terminus repeatedly surged and rapidly disintegrated through stagnate ice collapse and iceberg melting.
Their precise estimates of the timing, duration, and magnitude of Suðurjökull’s surges, provide ideal targets for the next generation of glacier surge models that may improve our ability to estimate future glacier mass loss rates if summer temperatures continue to rise.
Article: Precise chronology of Little Ice Age expansion and repetitive surges of Langjökull, central Iceland, Darren J. Larsen et al., Geology; http://dx.doi.org/10.1130/G36185.1.