Unprecedented Greenland Glaciology Database

Posted by William Colgan on September 23, 2016
Glaciology History, New Research / No Comments

The glaciological archive of the Geological Survey of Denmark and Greenland has accumulated both dust and documents over the years. This makes searching through this archive for glacier surface mass balance measurements a tedious task, as it means looking at every individual item. The occasional discovery of hand-written field notes describing a ten-year surface mass balance record can feel like finding a diamond in the rough.

Over the past five years, Horst Machguth led a team of 34 authors from 18 institutions in a near-exhaustive collection of historical surface mass balance observations from the Greenland ice sheet ablation area and peripheral glaciers. The database, which now contains 3000 measurements of surface mass balance, was published online this July in the Journal of Glaciology1. The measurements span 123 years, from the earliest surface mass balance measurements of Erich von Drygalski’s 1882-1883 Greenland Expedition of the Berlin Geographical Society, up to present-day automated weather station measurements.

temporal_overview_incl_map_v5_flat

Figure 1 – Overview of the data contained in the surface mass-balance database. (a) Temporal availability of data for each site and temporal resolution of the data. (b) Number of active measuring sites over time. (c) Number of active measuring points over time.

Approximately 60 % of the measurements were sourced from grey literature and unpublished documents scoured from the archives of the Geological Survey of Denmark and Greenland. Almost forgotten and inaccessible to scientists outside the Survey, they are essentially once again “new to science”. Some measurements, however, remain elusive, like those of Simpson’s 1952-1954 British North Greenland Expedition, and some other mid-20th Century expeditions.

Most measurements were made prior to the widespread adoption of handheld GPS devices. Making these data functional in today’s computer-based research environment turned out to be a major task, as it required translating numerous historical site diagrams into georeferenced latitude and longitude coordinate systems. Innovative solutions were adopted to translate ice surface elevation measurements made by the US Army Corps of Engineers (USACE) into surface mass balance values: cross-sectional profile of a supra-glacial access road could be translated into year-on-year changes in surface elevation equivalent to surface mass balance.

georef_nobles_v2_flat

Figure 2 – A US Army Corps of Engineering map of Nunatarssuaq Ice Ramp georeferenced with a modern digital elevation model.

Having brought together these temporally and spatially diverse measurements into a common digital database now offers an unprecedented opportunity to evaluate the accuracy of surface mass balance simulated by regional climate models. Even on their own, however, the data highlight the diverse rates of change in surface mass balance with elevation around the periphery of the Greenland ice sheet. The value of this data rescue project is perhaps highlighted by the fact that the database has already been used in at least five studies. The database provides a unique tool for understanding the climate sensitivity of Greenland glacier and ice sheet melt over the past century!

1MACHGUTH, H., THOMSEN, H.H., WEIDICK, A., AHLSTRØM, A.P., ABERMANN, J., ANDERSEN, M.L., ANDERSEN, S.B., BJØRK, A.A., BOX, J.E., BRAITHWAITE, R.J., BØGGILD, C.E., CITTERIO, M., CLEMENT, P., COLGAN, W., FAUSTO, R.S., GLEIE, K., GUBLER, S., HASHOLT, B., HYNEK, B., KNUDSEN, N.T., LARSEN, S.H., MERNILD, S.H., OERLEMANS, J., OERTER, H., OLESEN, O.B., SMEETS, C.J.P.P., STEFFEN, K., STOBER, M., SUGIYAMA, S., VAN AS, D., VAN DEN BROEKE, M.R. and VAN DE WAL, R.S.W. (2016) Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers. Journal of Glaciology, 1–27. doi: 10.1017/jog.2016.75.

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Suppressed Melt Percolation in Greenland Firn

Posted by William Colgan on May 19, 2016
Climate Change, New Research / No Comments

We have a new open-access study in the current volume of Annals of Glaciology that tracks the fate of meltwater in the relatively porous near-surface firn of the Greenland Ice Sheet using temperature sensors1 (available here). One of the main goals of this study was to understand what fraction of the meltwater produced at the ice sheet surface percolates vertically into the firn and locally refreezes, rather than leaving the ice sheet as runoff and contributing to sea level rise. The total retention capacity of all of Greenland’s firn could be a non-trivial buffer against sea level rise2.

For this particular study, we deployed firn temperature sensors at depths of up to 15 m at KAN_U. The sensors were automated to record data throughout the year, between our spring sites visits. KAN_U is located at 1840 m elevation in Southwest Greenland in the lower accumulation area. While KAN_U traditionally receives more mass from snowfall than it loses from melt, our study focused on the “extreme” 2012 melt season, which was the first year since records began that there was more meltwater runoff than snowfall at the site.

Fieldwork

Figure 1 – Lead author Charalampos Charalampidis drilling a borehole on the Greenland Ice Sheet near KAN_U during the 2013 spring field campaign.

As refreezing meltwater releases a tremendous amount of latent energy, the location of refreezing meltwater within the firn can be inferred from temperature anomalies. We assessed temperature anomalies by comparing our observed firn temperatures against modeled firn temperatures, whereby the modeled temperatures only accounted for heat exchanged with the ice sheet surface via diffusion, not latent heat release. This allowed us to identify depths where firn temperatures were warmer than expected.

Babis_thermistor

Figure 2 – Automated observations of firn temperatures in the top 10 m of firn at KAN_U over four years. There is a strong annual cycle in near-surface firn temperatures.

We found that despite 2012 being an extreme melt year, meltwater percolation and refreezing only occurred to 2.5 m depth during the melt season. It was only after the end of the melt season that some meltwater managed to percolate and refreeze in discrete bands at 5.5 and 8.5 m depth. This inference of relatively inefficient vertical meltwater percolation during the melt season appears to support the idea that thick and impermeable ice lenses that had previously formed within the firn during 2010 were inhibiting the percolation of 2012 meltwater3.

Maintaining the relatively sensitive automatic weather station needed to accurately measure firn temperatures and surface energy fluxes in the relatively harsh ice sheet environment was no easy task. It took a number of scientists and funding agencies, which are listed in the acknowledgement section of the paper, to make this study possible. The KAN_U weather station continues to report real-time climate data via the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) data portal: www.promice.dk.

KAN_U_location

Figure 3 – A: Location of Kangerlussuaq Upper Station (KAN_U) on the Greenland Ice Sheet. B: A PROMICE climate station deployed to measure firn temperatures and surface energy budget.

1Charalampidis, C., D. van As, W. Colgan, R. Fausto, M. MacFerrin and H. Machguth. 2016. Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet. Annals of Glaciology. doi:10.1017/aog.2016.2.

2Harper, J., N. Humphrey, W. Pfeffer, J. Brown and X. Fettweis. 2012. Greenland ice-sheet contribution to sea-level rise buffered by meltwater storage in firn. Nature. 491: 240-243.

3Machguth, H., M. MacFerrin, D. van As, J. Box, C. Charalampidis, W. Colgan, R. Fausto, H. Meijer, E. Mosley-Thompson and R. van de Wal. 2016. Greenland meltwater storage in firn limited by near-surface ice formation. Nature Climate Change. 6: 390–393.

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Canadian Military Support for Arctic Science?

Posted by William Colgan on April 14, 2016
Commentary, Communicating Science, Glaciers and Society / No Comments

I wish Canada would seriously consider developing a stronger civilian-military partnership in the areas of Arctic science and defense. The highly efficient partnership between the US National Science Foundation (NSF) and the US Air National Guard (ANG) in Greenland provides an impressive example.

IMG_6514

A US Air National Guard ski-equipped C-130, here dropping off researchers and equipment at Dye-2 on the Greenland Ice Sheet, costs approximately CAD 9000 per flight hour.

The 109th ANG wing essentially transports scientists and their equipment from the continental US to research bases in Greenland, and sometimes even on to the ice sheet, in return for full-cost payment from the NSF. The NSF-ANG full-cost special airlift arrangement (SAAM) delivers one C-130 transport plane flight hour for about CAD 9000.

In Canada, by comparison, High Arctic researchers generally travel to the main Polar Continental Shelf Project (PCSP) research base in Resolute, Nunavut, via commercial flights. A single Ottawa to Resolute round-trip ticket is about CAD 4000. But this ticket only comes with a 32 kg baggage allowance, and researchers are generally heavy packers. With checked bag penalties reaching almost CAD 200, it is easy to spend another CAD 1000 on baggage over above ticket price. Often, there is also an institutional overhead of about 40% on commercial purchases, meaning funding agencies ultimately pay close to CAD 7000 to get a single Canadian researcher and their equipment to Resolute; not far off a C-130 flight hour.

Flights to Resolute might seem like an esoteric topic, but Canada sends a lot of researchers there. The PCSP supports approximately 850 field researchers each year. That means at least CAD 3.4M in the direct cost of commercial air tickets, or closer to CAD 6.0M when indirect (overhead and baggage) costs are factored in. The NSF-ANG partnership seems to suggest that Canada could be getting more bang for these bucks. For example, while commercially flying ten researchers and equipment roundtrip between Ottawa and Resolute is about CAD 70K (incl. indirect costs), the ANG can fly more than twice that payload on the same route for about 81K. The ANG can even land that payload “open field” far from any airport.

025 Apr 23, 6 35 31 AM

Researchers and equipment in a US Air National Guard C-130, en route to the Greenland Ice Sheet Dye-2 ski-way, during the Arctic Circle Traverse 2013 (ACT13) campaign.

Adopting a civilian-military partnership for Canadian Arctic research would clearly improve the return on expenditure for Canadian research agencies, while also providing an almost zero-cost mechanism for increased military presence in the Canadian Arctic, which translates into enhanced standby transport or search-and-rescue capacity. The NSF-ANG partnership also shows that in addition to producing tangible benefits, “soft” benefits associated with direct, widespread, and meaningful interaction between military and civilian personnel can be cultivated.

So, I am delighted to hear that the Canadian military is learning how to build ski-ways on which ANG C-130s can land. For an Arctic researcher like myself, the next ideal step would be getting skis on a Canadian C-130 (technically converting it into an LC-130), and then getting research agencies to pay the military to fly that ski-equipped C-130 to some useful field sites throughout the Canadian High Arctic!

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FirnCover 2016 Greenland expedition route

Posted by William Colgan on March 15, 2016
New Research / No Comments

Our Arctic Circle Traverse 2016 (“ACT16”) campaign is getting underway next month, and one look at the expedition map and it seems like we’ve outgrown our name! The ACT expedition series began in 2004, as snowmobile traverses roughly aligned with the Arctic Circle (66 °N) in support of the NASA Program for Arctic Regional Climate Assessment (PARCA). Since the 2013 initiation of the NASA FirnCover program, however, there has been a strong motivation to simultaneously sample more remote sites on the ice sheet. Firn compaction rate, the key process that FirnCover seeks to measure and model, is sensitive to both air temperature and snowfall rate. That means firn compaction rates vary with latitude and elevation, so when the FirnCover team goes to Greenland, we try to sample the ice sheet from North-South and low-high. That makes for a lot of travel!

ACT16_expedition_route

Figure 1 – Logistics behind our Arctic Circle Traverse 2016 (ACT16) expedition route. Red denotes US Air National Guard flights. Purple denotes NSF charter flights. Green denotes commercial flights. Blue denotes snowmobile traverses.

This April the ACT16 team will gather in Schenectady, NY to hitch a ride to Kangerlussuaq, GL with the US Air National Guard. After a pause in Kanger, the 109th Airlift Wing will deliver us to their Camp Raven skiway near Dye-2 in the ice sheet interior. Once in the ice sheet interior, the ACT16 team will fission into two groups, with a base group staying at Dye-2 for detailed firn measurements, and a traverse group snowmobiling to firn instrumentation sites along the Arctic Circle. Afterwards, our two groups will join up and catch an NSF charter flight off the ice to Kanger for some brief decompression. Then a subset of the ACT16 team will fly north to Summit and the NEGIS deep coring site for more firn instrumentation and measurements. Eventually we’ll make our way back to Kanger and head home on commercial flights via Iceland. With military and NSF charter flights, temperamental snowmobiles, and a mix of commercial airlines, the logistics for this five week field season are pretty intense!

C130_icecap

Figure 2 – A ski-equipped C-130 from the 109th Airlift Wing of the US Air National Guard taxiing on the Camp Raven skiway near Dye-2 during ACT13.

I’m most excited to visit NEGIS, not because I think it will be any more (or less) spectacular than any other location in the ice sheet interior, but simply because I haven’t been there before. A new dot on the map is always cause for delight. This field season, however, I will be keeping track of my personal carbon footprint, and I expect the charter flight to NEGIS and back is going to figure prominently in that calculation.

This post is cross-posted on the FirnCover blog.

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Glacier Crevasses: A Review

Posted by William Colgan on February 29, 2016
New Research / No Comments

We have a new review paper on glacier crevasses in the current issue of Reviews of Geophysics1. We survey sixty years of crevasse studies, from field observations to numerical modeling to remote sensing of crevasses, and also provide a synthesis of ten distinct mechanisms via which crevasses influence glacier mass balance.

Two years ago, our team embarked on what was supposed to be a brief review of crevasse science to help interpret maps of Greenland crevasse extent that we are generating from laser altimetry data as part of a NASA project entitled “Assessing Greenland Crevasse Extent and Characteristics Using Historical ICESat and Airborne Laser Altimetry Data”. The final review ended up containing 250 references and being 43 typeset pages in length. Evidently we found the crevasse life cycle contained more nuances than we had initially assumed! Here are some of the highlights that have shifted our paradigm:

Field observations – Although crevasses are conventionally conceptualized to initiate at the surface and propagate downwards, we were surprised to find compelling evidence that at least some crevasses initiate at several metres depth, before propagating upwards to appear at the glacier surface. For example, observations that new crevasses can intersect relict crevasses at angles as low as 5 ° indicates that the stresses governing fracture are below the depth of relict crevasses (as relict crevasses do not serve as stress foci). This has implications for interpreting “buried” crevasses as relict or active.

Crevasse_Field_Sample

Figure 1 – Measured principal strain rates and crevasse locations observed circa 1995 at Worthington Glacier, USA2. The cross-cutting of relict crevasses by active crevasses indicates relative crevasse chronologies can exist at a single point on a glacier.

Numerical modeling – While crevasses have conventionally been assumed to form perpendicular to principal extending stresses on glaciers, we were intrigued to find strong model evidence that non-trivial crevasse curvature and rotation can result when there is substantial shearing (Mode III fracture) acting in addition to the more the common opening (Mode I fracture). The role of such mixed-mode fracture in shaping crevasse geometry has implications for interpreting curved / rotated crevasses as either deformed following opening or in equilibrium with local shear.

Crevasse_Modes

Figure 2 – Schematic illustrating the three modes of fracture: Mode I (opening), Mode II (sliding), and Mode III (tearing).

Remote Sensing – Remote sensing technologies for crevasse detection exhibited remarkable growth over the past 60 years. Real-time crevasse detection for traverse vehicles advanced from Cold War era rudimentary push-broom “dishpans”, which measured bulk electric current density of surrounding ice, to modern fully autonomous rovers capable of executing ground penetrating radar grids. In terms of satellite imagery, crevasses went from being manually delineated in the coarse resolution visible imagery that became available in the 1970s to now being automatically detected by feature tracking algorithms in higher resolution visible and synthetic aperture radar imagery.

CrevassePastPresent

Figure 3 – Left: Cold War era “dishpan” detection system that inferred crevasses from changes in bulk electric current density3. Right: An autonomous ground-penetrating radar unit (Yeti) being used to map near-surface buried crevasses at White Island, Antarctica. (Photo: Jim Lever)

Mass Balance Implications – While many studies have described individual mechanisms by which crevasses can influence glacier mass balance, we wanted to provide an overview of all the possible mechanisms, and we were fortunate enough to have a graphic artist help us do it in a single schematic. The mass balance implications of crevasses contain several counter-intuitive nuances. For example, crevasses can enhance basal sliding in the accumulation area and suppress basal sliding in the ablation area. Given their myriad mass balance implications, however, crevasses may serve as both indicators and agents of changing glacier form and flow.

Crevasse_Summary

Figure 4 – Schematic overview of the various processes through which crevassed surfaces influence glacier mass balance relative to non-crevassed surfaces: (1) increased solar energy collection and enhanced surface ablation, (2) increased turbulent heat fluxes and enhanced surface ablation, (3) decreased buried crevasse air temperatures and suppressed ice deformation, (4) increased bulk glacier porosity and enhanced ablation area water retention, (5) increased supraglacial lake drainage and suppressed accumulation area water retention, (6) increased supraglacial lake drainage and enhanced ice deformation, (7) attenuated transmission of hydrologic variability (relative to moulins) and suppressed basal sliding velocities, (8) increased cryo-hydrologic warming of ice temperatures and enhanced ice deformation, (9) increased water content / hydraulic weakening and enhanced ice deformation, and (10) iceberg calving.

1Colgan, W., H. Rajaram, W. Abdalati, C. McCutchan, R. Mottram, M. S. Moussavi and S. Grigsby. 2016. Glacier crevasses: Observations, models, and mass balance implications. Reviews of Geophysics. 54: doi:10.1002/
2015RG000504.

2Harper, J., N. Humphrey and W. Pfeffer. 1998. Crevasse patterns and the strain-rate tensor: A high-resolution comparison. Journal of Glaciology. 44: 68–76.

3Mellor, M. 1963. Oversnow Transport. Cold Regions Science and Engineering. Monograph III-A4. 104 pages.

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Greenland Ice Sheet Melt-Albedo Feedback

Posted by William Colgan on December 01, 2015
Climate Change, New Research / No Comments

We have a new study in the current issue of The Cryosphere that looks at the surface energy budget at a site on the Greenland Ice Sheet, and particularly the energy available for meltwater production, over a five-year period spanning the 2010 and 2012 exceptional melt years1. While both the summers of 2010 and 2012 were exceptionally warm, only 2012 resulted in a negative mass balance. In fact, 2012 was the first year since records began that there was more meltwater runoff than snowfall at the site (KAN_U at 1840 m elevation in Southwest Greenland).

In the study we describe how the 2010 exceptional melt year appears to have preconditioned the near-surface layers of the ice sheet to dramatically strengthen the melt-albedo feedback in the subsequent 2012 exceptional melt year. Essentially, we suggest that near-surface ice lenses created by refreezing meltwater in the 2010 melt season made the ice sheet surface transition more readily from relatively high albedo light snow to relatively low albedo dark ice in the 2012 melt season. The substantially darker 2012 ice sheet surface absorbed more solar energy, and therefore caused more melt per ray of sunshine, than in 2010. We estimate that this melt-albedo feedback resulted in approximately 58 % more solar energy absorbed, and available for melt, in 2012 than in 2010.

While 2010 and 2012 were exceptional melt seasons in the context of the past thirty years, they are likely to have foreshadowed the upcoming thirty years. As Greenland climate is now rapidly warming, summer melt intensity no longer oscillates around its long term mean, and instead previously exceptional events are becoming normal. We therefore speculate that under persistent climate change, the firn at the KAN_U site will likely become saturated with refrozen ice lenses, which will enhance the melt-albedo feedback and perhaps even inhibit the downward percolation of meltwater. Ultimately, this will accelerate the transition of the contemporary lower accumulation area underlain by firn into an ablation area underlain by superimposed ice.

Maintaining the relatively sensitive automatic weather station needed to accurately measure surface energy fluxes in the relatively harsh ice sheet environment was no easy task. It took a number of scientists and funding agencies, which are listed in the acknowledgement section of the paper, to make this study possible. The KAN_U weather station continues to report real-time climate data via the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) data portal: www.promice.dk.

2010_2012_Fluxes

Figure 1 – Monthly mean energy fluxes observed at KAN_U: shortwave (ES), longwave (EL), sensible heat (EH), evaporative (EE), geothermal (EG), precipitation (EP) and melt (EM). The melt flux was calculated as a residual.

KAN_U_location

Figure 2 – A: Location of Kangerlussuaq Upper Station (KAN_U) on the Greenland Ice Sheet. B: The PROMICE climate station deployed to measure surface energy budget.

1Charalampidis, C., D. van As, J. Box, M. van den Broeke, W. Colgan, S. Doyle, A. Hubbard, M. MacFerrin, H. Machguth and C. Smeets. 2015. Changing surface–atmosphere energy exchange and refreezing capacity of the lower accumulation area, West Greenland. The Cryosphere. 9: 2163-2181.

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New Report: Applied Glaciology Primer

Posted by William Colgan on November 13, 2015
Applied Glaciology, Glaciers and Society / No Comments

The Geological Survey of Denmark and Greenland (GEUS) has been involved in several applied glaciology projects since the early 1980s, such as assessments for the hydropower plants now operating at Ilulissat and Nuuk, and glacial lake outburst flood assessments for Isortuarsuup and Qorlortossup in South Greenland. In a report entitled “Unique applied glaciology challenges of proglacial mining” in this year’s Report on Geological Survey Activities, we provide a brief overview of four unique glacier-related geotechnical challenges confronting industrial operations adjacent to a glacier. We discuss these four especially unique applied glaciology challenges in the context of a new generation of mining projects that seek to excavate through glaciers to reach sub-glacial ore, such as the active Kumtor Mine in Kyrgyzstan and the approved Isua Mine in Greenland. The four uniquely glacier-related geotechnical challenges we discuss are supraglacial runoff, subglacial water flow, ice movement and supraglacial access roads. We also highlight how climate change is poised to further exacerbate these geotechnical challenges, as increased meltwater production generally enhances both water flow and ice flow into proglacial sites. We hope this report can serve as a quick survey of recent applied glaciology activities for non-specialists.

ROSA_sites

Site overviews of the recently approved Isua project in Greenland (left) and the recently approved Kerr-Sulphurets-Mitchell and Brucejack projects in Canada (right).

*W. Colgan, H. Thomsen and M. Citterio. 2015. Unique applied glaciology challenges of proglacial mining. Geological Survey of Denmark and Greenland Bulletin. 33: 61–64.

*This report serves as the citation for the proglacial mining projects open-file located here.

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New Book: Iluliaq – Isbjerge – Icebergs

Posted by William Colgan on September 22, 2015
Climate Change, Communicating Science, Glaciers and Society / No Comments

I was very pleased to have the opportunity to write a preface for Iluliaq – Isbjerge – Icebergs, which contains 100+ pages of watercolours and photographs depicting diverse icebergs around Greenland, along with accompanying Danish/English narration about the iceberg lifecycle (ISBN 978-87-93366-34-3 | available here). I am very supportive of projects like this, which seek to bridge the arts-sciences chasm. It was actually science-editing the iceberg factoids in this book that compelled me to start providing mass loss rates in equivalent tonnes per second in my subsequent publications. I now find saying that Greenland is losing 262 gigatonnes of ice per year, is more abstract than saying it is losing 8300 tonnes per second. Evidently, my perspective was shifted by this delightful project! Below I provide the preface in full.

iluliaq

Preface for Iluliaq – Isbjerge – Icebergs:

“While an individual iceberg is ephemeral, icebergs are a ubiquitous feature of Greenland’s landscape. The shifting nature of icebergs, a constantly drifting and capsizing population, makes them challenging to observe. As they are partway through the transition from glacier ice into ocean water, icebergs are somewhat peripheral to both glaciology/geology and oceanography. Despite these intrinsic difficulties in their study, however, icebergs have never been more important to society than today. Due to climate change, Greenland’s glaciers are now flowing faster than a century ago. The resulting increase in Greenland’s iceberg production is now raising global sea level by 2 cm each decade.

In contrast to the iconic climate change indicators of diminishing sea ice area and glacier volume, there are now more icebergs being produced than a century ago. This provides a very strong motivation to understand the iceberg lifecycle. This lifecycle begins with a thunderous calving at genesis, followed by years of slow drifting and reduction, and quietly ends when the last ice melts into water. In this book, Pernille Kløvedal Nørgaard, Martin von Bülow and Ole Søndergaard provide visually compelling insights on selected aspects of this lifecycle.

By ensuring they not only communicate the natural majesty, but also climatic importance, of Greenland’s icebergs, the authors are helping icebergs assume a rightful place in contemporary public consciousness. The sense of humility evoked by the icebergs depicted here will be familiar to Arctic enthusiasts. These photos and watercolours represent multiple expeditions and extensive travels around Greenland. Similar to documentarians and artists who have accompanied polar expeditions since the Victorian Era, the authors have intentionally sought out a harsh environment, and invited confrontation with adverse conditions, to encapsulate a unique feature of Earth that most people could otherwise never appreciate. Society benefits from such hardy souls, whose passion for nature allows bleak and inaccessible landscapes to be transmitted into our civilized homes.”

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Kokanee Glacier Beer and the 1962 “Bomb Horizon”

Posted by William Colgan on August 28, 2015
Cold War Science, Glaciers and Society / No Comments

Dear Kokanee Beer,

I was delighted to hear that, in celebration of Kokanee’s founding in 1962, you’ve decided to sponsor some glaciology research in exchange for the recovery of five liters of glacier ice from 1962. It just so happens that 1962 is also an auspicious year for glaciologists. We glaciologists know 1962 as the “bomb horizon”, due to a worldwide peak in the atmospheric deposition rates of radionuclides derived from thermal weapons testing. Tsar Bomba, the largest thermal-nuclear weapon ever tested, with a yield of over 50 MT, had just been detonated the previous fall (30 October 1961). The USSR conducted about 40 thermal-nuclear weapons tests in 1962, and the US conducted closer to 100! After each test, the radionuclide fallout drifted around the atmosphere for a few weeks before raining down on the landscape, glaciers included.

Fortunately for us glaciologists, the glaciers proved to be really effective in retaining those radionuclides under subsequent snowfall. These days, we can just drill a deep hole in a glacier, lower down a gamma spectrometer, find the peak in radioactivity, and get a quick estimate of the 1962 depth. As you can see from the attached graph of radioactive 137Cs decay with depth, the present-day radioactivity of the 1962 “bomb horizon” is about equivalent to the background radioactivity found today at the glacier surface. So, 1962 melted glacier water is definitely not worse to drink than 2015 melted glacier water, I was just thinking that instead of calling your beer Deja Brew, maybe you should perhaps consider Thermonuclear Haze or even Cesium Peak to really give a fair nod to your 1962 glacier roots?

Yours truly,

William Colgan, Ph.D.

Thermo_Wiki2

Figure 1 – Annual count of world wide thermo-nuclear weapons tests between 1945 and 2013. By far, 1962 was the peak in number of weapons tested. (from Wikipedia)

Thermo_profile

Figure 2 – Profile of radioactive cesium (137Cs) with depth, as well as control profile from a  cadmium (109Cd) source located on the detector, recovered from the Devon Ice Cap in the Canadian Arctic in 2005. The arrow points to the apparent 1962 “bomb horizon”. We talk about using this independent dating technique for ice cores in Colgan and Sharp (2008).

Colgan, W. and M. Sharp. 2008. Combined oceanic and atmospheric influences on net accumulation on Devon Ice Cap, Nunavut, Canada. Journal of Glaciology. 54: 28-40.

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Vanishing Canada: Group of Seven Landscapes Under Climate Change

Posted by William Colgan on July 31, 2015
Climate Change, Communicating Science / 3 Comments

In collaboration with Virginia Eichhorn of the Tom Thomson Art Gallery, I am hoping to get a very interdisciplinary arts and sciences project underway that looks at the impact of recent and projected climate change on the Canadian landscapes painted by the Group of Seven. The exceptionally vivid expressionist landscape scenes painted by the Group of Seven between 1920 and 1935 have become Canadian cultural icons. The temperature and precipitation trends associated with climate change, however, are changing these landscapes, most visibly through changes in vegetation, snow and glacier extent, lake or sea ice extent, and flood or drought frequency (Figure 1). We intend to reframe Group of Seven paintings as unique time capsules of a vanishing Canada, rather than portraits of an intransient Canada.

Mount_Robson_mockup

Figure 1 – Highly visible landscape change at Mount Robson due to air temperature change. Red shading denotes glacier area change since Lawren Harris originally painted this scene c. 1930.

To do this, we are seeking to dispatch contemporary emerging artists across Canada, to landscapes featured in Group of Seven works, to re-paint impressions of these landscapes under one of three IPCC Representative Concentration Pathways (RCPs). These RCPS, ranging from RCP 4.5 to RCP 8.5, essentially range from “optimistic” to “pessimistic” CO2emissions reductions scenarios. For example, RCP 4.5 simulates 4.5 W/m2 increased radiative forcing in year 2100 relative to year 1850, while RCP 8.5 simulates 8.5 W/m2, or almost twice as much, anomalous radiative forcing associated with well-mixed greenhouse gases from anthropogenic sources.

Mock_up2

Figure 2 – Envisioning a landscape in 2100 under three IPCC scenarios that vary from the “optimism” of RCP 4.5 to the “pessimism” of RCP 8.5. Byng Inlet was originally painted by Tom Thomson c. 1920.

We are ultimately aiming for a cross-disciplinary arts and sciences exhibition that will place specific Group of Seven landscapes, and more broadly Canada’s landscape, in the context of ongoing climate change in a highly visual fashion. Inspired by ArtTracks150, we are hoping that Canada’s 150th birthday (July 2017) may provide a natural window of increased public awareness of centurial time-scales, during which we might briefly focus public attention on the multi-generational implications of climate change on the Canadian landscape. Virginia and I welcome you to contact us for more information on, and ways to get involved with, this project.

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