Monthly Archives: November 2014

Greenland data rescue: An appeal

Posted by William Colgan on November 24, 2014
Communicating Science, Glaciology History, New Research / No Comments

As described in this month’s newsletter No 7, the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) is nearing completion of its comprehensive database of surface mass budget observations from the Greenland ice sheet melt area and peripheral glaciers. We now have just over 2400 unique observations spanning from the 1938 Freja Glacier expedition to the present. Approximately half these observations have never been published. These historic measurements were fragmented across studies, most of which were pre-digital or unpublished, effectively making this highly valuable data inaccessible to the global research community. Despite our best efforts, however, we are still missing data from a handful of known expeditions. For example, does someone you know perhaps have a copy of Alfred Wegener’s 1930 Qaamarujuk Glacier observations? There is a chance we might even be unaware of some expeditions, especially recent private sector prospecting work. Please get in touch with Horst Machguth (homac@byg.dtu.dk) of the www.promice.dk team if you can help us out with this community data assimilation project!

Colgan, W., H. Machguth and A. Ahlstrom. 2014. Data Rescue: Greenland Surface Mass Budget Database. PROMICE newsletter No 7. Ed. S. Andersen and H. Pedersen.

database_map

Map of the location, with temporal description, of the Greenland ice sheet melt area and local glacier surface mass budget observations presently contained in the database. The grey sites are the missing data (from a manuscript in preparation).

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Greenland ice loss: 8300 tonnes per second

Posted by William Colgan on November 19, 2014
Communicating Science, New Research, Sea Level Rise / No Comments

We have a new study coming out in Earth and Planetary Science Letters that looks into the mass loss of the Greenland ice sheet (Andersen et al., 2015). We used the “input-output” approach, whereby an estimated iceberg production rate is differenced from an estimated snow accumulation rate. The input-output approach we used was slightly different from previous studies (such as Rignot et al., 2008 or Enderlin et al., 2014) because the ice sheet perimeter across which we observed ice flow (or the “flux gate”) was relatively far inland. That meant we had to make a different assumption about the vertical velocity profile at the flux gate, as well as account for changes in ice volume between the flux gate and the tidewater glacier grounding lines. We also used a new combination of satellite-derived ice surface velocity product, airborne radar-derived ice thickness observations, and surface mass balance simulations. Despite all this, our mass loss estimate agrees pretty well with previous studies!

The numbers are pretty striking: We estimate that between 2007 and 2011 the Greenland ice sheet alone, not counting all the peripheral glaciers in Greenland, lost 262 Gt of ice per year. That works out to about 8300 tonnes per second! That means the Greenland ice sheet probably weighs 250,000 tonnes less than when you started reading this blog post. No wonder we can measure its mass loss by gravitational anomalies! The ice sheet is currently losing mass via both surface runoff (the difference between accumulation and melt) and ice dynamics (the production of icebergs). We estimate that runoff comprised about 61 % of the ice sheet’s mass loss, or about 5000 tonnes per second, with iceberg production comprising the remaining 3300 tonnes per second of mass loss. Some big numbers that confirm the Greenland ice sheet is presently raising global mean sea level by about 0.73 mm per year.

Enderlin, E., I. Howat, S. Jeong, M. Noh, J. van Angelen & M. van den Broeke. 2014. An improved mass budget for the Greenland ice sheet. Geophysical Research Letters. 41: doi:10.1002/2013GL059010.

Rignot, E., J. Box, E. Burgess & E. Hanna. 2008. Mass balance of the Greenland ice sheet from 1958 to 2007. Geophysical Research Letters. 35: doi:10.1029/2008GL035417.

Andersen, M., L. Stenseng, H. Skourup, W. Colgan, S. Khan, S. Kristensen, S. Andersen, J. Box, A. Ahlstrøm, X. Fettweis & R. Forsberg. 2015. Basin-scale partitioning of Greenland ice sheet mass balance components (2007–2011). Earth and Planetary Science Letters. 409: 89–95. doi:10.1016/j.epsl.2014.10.015.

Greenland_InputOutput

Diagram showing differences in methodology between our study (TOP) and previous studies (BOTTOM) in converted estimated ice flux (F) into estimated iceberg production (D). We adopt a higher elevation “flux gate”, which necessitates accounting for downstream changes in ice volume (∆S), as well as making a different assumption about the vertical velocity profile at the flux gate. We also use different velocity and ice thickness observations, and a different surface mass balance (SMB) model (from Andersen et al., 2015).

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Sixty Years of Snow Runways

Posted by William Colgan on November 14, 2014
Cold War Science, Glaciology History / 1 Comment

About sixty years ago, in September 1955, the US Army Corps of Engineers conducted the first test landings of wheeled military transport planes on a prepared snow runway at Site II, Greenland. The 3000 meter (10,000 foot) snow runway was prepared by repeatedly pulverizing and compressing the ice sheet’s snow surface with low ground pressure tractors. Driving the tractors from Camp TUTO to Site II, high in the ice sheet interior, took several days.

Eight successful landings with a C-47 Skytrain, led to six successful landings with a C-54 Skymaster, and finally seven successful landings with a C-124 Globemaster. Landing the pug-nosed C-124, which has an empty weight of 45,000 kg (100,000 lbs), on prepared snow runways formed the backbone of ice sheet logistics in both Greenland and Antarctica throughout the International Geophysical Year (1957-1958). The slightly more nimble ski-equipped LC-130 Hercules, now a symbol of polar research, was not tested in Northwest Greenland for six more years.

So, perhaps a nod to the 60th anniversary of snow runways, without which ice sheet camps and their precious ice cores and other glaciological data would not be possible!

Correction: In an earlier post version I said the first C-124 usage of a snow runway was in September 1954. In fact, the snow runway technique was developed in September 1954, but the first C-124 usage of a snow runway was not until September of 1955. The 59.5th anniversary of transport planes and snow runways?

Polar Ice Coring and IGY 1957-58: An Interview with Dr. Anthony J. “Tony” Gow.

(skimmed from my upcoming Cold War science project.)

 

C124_icecap

A wheeled C-124 Globemaster unloading on a snow runway at McMurdo Station, Antarctica, to deliver a smaller ski-equipped plane in 1956 (photo by Jim Waldron; http://icecores.org)

C130_icecap

A ski-equipped C130 Hercules taxing at Dye-2, Greenland, after dropping of our field party for there weeks in the spring of 2013. (personal photo!)

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Glacier Mining: Geotechnical and Social Exceptionalism

Posted by William Colgan on November 07, 2014
Applied Glaciology, Climate Change, Glaciers and Society / 1 Comment

When the glaciology lexicon was in its infancy, Carl Benson described glaciers as “monomineralic metamorphic rocks” in his pioneering work with the US Army Engineers1. Given the lower density and strength of ice than coal, it may seem like glacier ice is an easy overburden to remove for open pit mining. Experience, however, has demonstrated that there are exceptional geotechnical challenges associated with removing glacier ice overburden. These challenges stem from geometry, hydrology and phase, all of which change far more rapidly in glaciers than hard rock2. The apparent surge of a waste rock pile at the Kumtor Mine, in Kyrgyzstan, highlights the exceptional geotechnical challenges confronting Centerra Gold in maintaining the world’s largest open ice pit mine.

With glaciers serving as a highly visible indicator of climate change, glacier mining projects often face exceptional social challenges in comparison to conventional hard rock mining projects. The Pascua Lama Mine, which spans the Chile-Argentina border, highlights how glacier preservation is a global movement that adapts to local issues. Glaciers therefore serve as the basis for a “glocal”, or globalized local, social movement3. Barrick Founder Peter Munk has commented on the social challenges confronting Pascua Lama: “It’s not enough to have money, it’s not enough to have reserves, it’s not enough to have great mining people. Today, the single most critical factor in growing a mining company is a social consensus – a license to mine.”4

The combination of long term increases in resource demand, retreating glaciers due to climate change, and improved mining technology and prospecting techniques, are making the exploitation of pro- and sub-glacial mineral deposits more feasible. This means a more widespread confrontation of the geotechnical and social exceptionalism of glacier mining in the coming decades!

Kumtor_1975_2013

Glacier and waste rock extent between 1975 and 2013 in the vicinity of Kumtor Mine (from Landsat archive).

PascuaLama

Glaciers in the vicinity of the Pascua Lama Mine on the Chile-Argentina border (from WikiCommons).

1Benson, C. 1962. Stratigraphic studies in the snow and firn of the Greenland ice sheet. Snow, Ice and Permafrost Research Esatablishment. US Army. Research Report 70.

2Colgan, W. and L. Arenson. 2013. Open-Pit Glacier Ice Excavation: Brief Review.
Journal of Cold Regions Engineering. 27: doi:10.1061/(ASCE)CR.1943-5495.0000057.

3Urkidi, L. 2010. A glocal environmental movement against gold mining: Pascua–Lama in Chile. Ecological Economics. 70: 219-227.

4Smith, C. 2014. Sustainability Challenges: When Good Intentions Backfire. NSEAD Knowledge

Additional Landsat images of Kumtor here.

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KSM Project gets provincial approval

Posted by William Colgan on November 03, 2014
Applied Glaciology, Climate Change, Glaciers and Society / No Comments

The Kerr-Sulphurets-Mitchell (KSM) gold mine in British Columbia received provincial approval last week. The federal permitting decision is expected in November. The suite of three open pits are in close proximity to glaciers, with the ultimate outline of the Mitchell pit intersecting the present extent of Mitchell Glacier. The proponent report filed by Seabridge Gold Inc states: “The current recession rate of the Mitchell Glacier has been estimated by Seabridge geologists at 100 m per year. As mining progresses, melting of the ice is expected to clear the area for the ultimate pit and create space needed for a series of diversion dams and ponds as well as the required debris catch basins upstream of the diversion inlets.” Seabridge is also seeking to excavate a 22 km long haulage tunnel that will convey 120,000 tonnes per day of ore underneath glaciers north of the open pits. A 38 km long glacier road, which ascends Berendon Glacier, crosses a local topographic divide, and descends an unnamed glacier, will provide winter access to the trio of open pits. The Berendon Glacier access road would be close proximity to the Knipple Glacier access road proposed by Pretium Resources Inc to access the nearby Bruce Jack Mine. Presumably the KSM project will be keeping a close eye regional glacier projections!

Controversial Canadian KSM mine gets key govt. permits

KSM (Kerr-Sulphurets-Mitchell) Project: Canadian Environmental Assessment Agency

KSM_glacier_road

Kerr-Sulphurets-Mitchell Project glacier access road during the winter. The road ascends Berendon Glacier in the east, crosses the local topographic divide, and descends an unnamed glacier in the west.

KSM_site_map

Site map of the Mitchell Pit at the Kerr-Sulphurets-Michell gold mine. Purple line denotes haulage tunnel. Dashed black line denotes ultimate extent of Mitchell Pit. White areas denote glacier extent.

 

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