International Polar Year 2007–2008 - WMO

246
IPY 20 07–20 08
conditions. The general consensus is that all of these
environments almost certainly contain life, based on
the current knowledge of the settings, but that life
more complex than microbes is highly unlikely. Early
speculation that the water in these lakes has been
isolated for millions of years is also considered far less
likely given the degree of hydrological communication
apparent among those lakes examined to date.
A New Frontier Continues to Advance
during IPY
The early phases of subglacial aquatic environment
research coincided with initial planning for IPY
2007–2008. As a consequence, a group successfully
proposed to become an ICSU-WMO IPY project entitled
Subglacial Antarctic Lake Environments Unified
International Team for Exploration and Discovery
(SALE UNITED). As Antarctic science is funded by
National Programs, both SCAR SALE and SALE UNITED
served primarily as fora to exchange information and
network with others interested in subglacial aquatic
environments. SALE UNITED participants included
scientists and technologists from Belgium, Canada,
China, France, Germany, Italy, Russia, the U.K. and
the U.S.A. SCAR SALE (and during IPY, SALE UNITED)
held meetings in Austria (2005), France (2006), the
U.S. (2007), Russia (2008) and Belgium (2009) to
further development of strategic plans and sharing of
information on progress. In 2006, a large international
workshop “Subglacial Antarctic Lake Environment in
the IPY 2007–2008: Advanced Science and Technology
Planning Workshop” for the broader community was
convened in Grenoble, France by M.C. Kennicutt II
and J.R. Petit. The workshop brought together 84
participants from 11 countries.
During IPY, significant advances in understanding
subglacial environments were achieved. Wingham et
al., (2006) detected changes in ice-sheet surface elevations
in central East Antarctica using satellite remote
sensing and demonstrated that a lake in the Adventure
subglacial trench discharged approximately 1.8 km 3 of
water over a period of 14 months. The water flowed
along the axis of the trench and into at least two other
lakes some 200 km away. The flux of water, at around 50
m 3 s -1 , was equivalent to the flow of the River Thames
in London. This discovery was particularly significant as
the observations were from the center of East Antarctica,
which was considered to be a stable and ancient ice
sheet. The conclusion was that the movement of subglacial
water was likely everywhere in Antarctica and
indeed the hydrological processes have subsequently
been shown to be common-place. This work also suggested
that subglacial systems were linked together by
a network of hydrological channels defined by the basal
topography and surface slopes. Siegert et al., (2007)
showed the nature of these channels and suggested
how groups of lakes may be associated within discrete
systems. Later, Wright et al., (2008) revealed that the directions
of several such channels were sensitive to the
ice surface slope. They concluded that small changes
in surface slope can result in a major alteration to the
basal water flow, especially during periods of ice sheet
changes such as after the last glacial maximum or even
as a consequence of future global warming. These
findings also suggested that water would flow along a
hydrologic potential which in some instances might be
up topographic slopes (up-hill).
Further analysis of satellite remote sensing showed
that the process of subglacial discharge and water flow
was indeed common-place in Antarctica (Smith et al.,
2009). Additionally, many of the newly found lakes
and discharge areas were located at the heads of ice
streams (Siegert and Bamber, 2000; Bell et al., 2007).
Smith et al., (2009) showed, that these lakes actively
discharge water to ice stream beds altering basal flow.
Satellite investigations of the Byrd Glacier by Stearns
et al., (2008) revealed that this was the case and that
subglacial lake discharges coincide with 10% anomalies
in flow velocity in a major outlet glacier (Byrd)
draining East Antarctica. Hence, subglacial lakes can
and probably always have influenced the dynamics of
overlying ice sheets. Additional satellite imagery analysis
has confirmed the widespread existence of lakes
and episodic water release events. Evidence has also
been found of paleo-outbursts from subglacial lakes,
most notably the dramatic outflow features present in
the Labyrinth area of the McMurdo Dry Valleys. Vast
amounts of lake water were released from large lakes
and such events have been speculated to affect ocean
thermohaline circulation due to the influx of fresh water
possibly interacting with regional climate.
During these years, meetings and international
workshops facilitated the development of research