The full programme book (PDF) - Royal Geographical Society

T5
Changing tidewater glacier extent and response to climate from Little Ice Age to
present: observations and modelling of Kangiata Nunaata Sermia, SW Greenland.
J.M. Lea 1 *, D.W.F. Mair 1 , F.M. Nick 2,3 , B.R. Rea 1 , P.W. Nienow 4
1 Dept. of Geography, University of Aberdeen, Aberdeen
2 UNIS, Longyearbyen, Svalbard, Norway
3 GEUS, Copenhagen, Denmark
4 Dept. of Geography, University of Edinburgh, Edinburgh
Records of Greenlandic tidewater glacier (TWG) change are primarily restricted to the
period covered by satellite observation. This study extends the record of terminus change
of the tidewater outlet glacier Kangiata Nunaata Sermia (KNS), SW Greenland to its Little
Ice Age maximum (LIAmax). This is achieved using a combination of geomorphology,
written observations, and historical and satellite imagery. We explore likely marine and
atmospheric controls on terminus change by comparison with existing records of local air
and ocean temperatures and, for earlier periods, by modelling glacier response to
systematic changes in marine and oceanic forcings at the terminus.
Results from the glacier reconstruction show that retreat began in the late 18th century,
with the terminus retreating at least 12 km from its LIAmax by 1859. KNS then
experienced a period of relative stability before advancing to its 20th century maximum by
~1920. Significant retreat occurred from 1921-1965, before periods of advance and retreat
up until 1997. Subsequent to this, KNS has retreated by 2 km up to the end of the 2012
melt season. The LIAmax to present retreat of KNS totals 22.6 km. Comparison of
terminus fluctuations to local air temperature (1866-present) and sea surface temperature
(1870-present) anomalies demonstrate that air temperature exerts a significant modulating
control on terminus stability for the duration of the record. A state-of-the-art 1-dimensional
flow-band model driven by submarine melt (SM) and crevasse water depth (CWD; Nick et
al, 2010) is capable of reconstructing observed terminus fluctuations during earlier periods
for realistic values of SM using a range of CWD. This provides confidence that such
models are capable of predicting TWG terminus variability over centennial timescales.
Keywords: Greenland, Tidewater Glaciers, Little Ice Age, Numerical Modelling, Glacial
Geomorphology, Historical Records