Glaciers of the Arid Andes

A team of us, led by Christophe Kinnard, just published a paper synthesising a bunch of work done on a small glacier in the Arid Andes.

Kinnard, C., Ginot, P., Surazakov, A., Macdonell, S., Nicholson, L.I., Patris, N., Rabatel, A., Rivera, A. and Squeo, F. (2020) Mass-balance and climate history of a high-altitude glacier, Desert Andes of Chile. Frontiers in Earth Science, 8, 40.

Glaciers in the dry Chilean Andes provide important ecological services, yet their mass balance response to past and ongoing climate change is not that well studied. The new paper uses glaciological, geodetic, and ice core observations to examine recent (2002–2015), historical (1955–2005), and past (<1900) mass balance history of Guanaco Glacier (29.34°S, >5000 m) .The work was done by CEAZA and its partners, over a number of years, including those that I worked at CEAZA leading the glacier research group, which is now led by Shelley MacDonell.

I’ll admit that my contribution to this paper writing was very lightweight, but its great to see it out there, especially as I was involved in the mass balance work and the ice coring project of the Guanaco Glacier.

Glaciers and researchers in the Arid Andes

The main findings are summarised in the abstract:

  1. Analysis of mass balance and meteorological data since 2002 suggests that mass balance is currently mostly sensitive to precipitation variations, while low temperatures, aridity and high solar radiation and wind speeds cause large sublimation losses and limited melting.
  2. Mass balance reconstructed by geodetic methods shows that Guanaco Glacier has been losing mass since at least 1955, and that mass loss has increased over time until present.
  3. An ice core recovered from the deepest part of the glacier in 2008 revealed that the glacier is cold-based with a ?5.5°C basal temperature and a warm reversal of the temperature profile above 60-m depth attributed to the recent atmospheric warming trend. Detailed stratigraphic and stable isotope analyses of the upper 20 m of the core revealed seasonal cycles in the ?18O and ?2H records with periods varying between 0.5 and 3 m. w.e. a–1. Deuterium excess values larger than 10‰ suggest limited post-depositional sublimation, while the presence of numerous refrozen ice layers indicate significant summer melt. Tritium concentration in the upper 20 m of the core was very low, while 210Pb was undetected, indicating that the glacier surface in 2008 was at least 100 years old.
  4. Taken together, these results suggest that Guanaco Glacier formed under drastically different climate conditions than today, when humid conditions caused high accumulation rates, reduced sublimation and increased melting. Reconstruction of mass balance based on correlations with precipitation and streamflow records show periods of sustained mass gain in the early 20th century and the 1980s, separated by periods of mass loss. The southern migration of the South Pacific Subtropical High over the course of the 20th and 21st centuries is proposed as the main mechanism explaining the progressive precipitation starvation of glaciers in this area.

Here is a list of other works mostly produced by CEAZA and its partners on these small arid zone glaciers and their surroundings:

  • Réveillet, M.,MacDonell, S., Gascoin, S., Kinnard, C., Lhermitte, S., Schaffer, N. 2020. Impact of forcing on sublimation simulations for a high mountain catchment in the semiarid Andes. The Cryosphere, 14, 147–163. https://doi.org/10.5194/tc-14-147-2020
  • Rowe, P., Cordero, R., Warren, S., Stewart, E., Doherty, S., & Pankow, A., Schrempf, M., Casassa, G., Carrasco, J., Pizarro, J., MacDonell, S., Damiani, A., Lambert, F., Rondanelli, R., Huneeus, N., Fernandoy, F., Neshyba, S. (2019). Black carbon and other light-absorbing impurities in snow in the Chilean Andes. Scientific Reports, 9(1). doi: 10.1038/s41598-019-39312-0
  • Schaffer, N., MacDonell, S., Réveillet, M., Yáñez, E., & Valois, R. (2019). Rock glaciers as a water resource in a changing climate in the semiarid Chilean Andes. Regional Environmental Change, 19(5), 1263-1279. doi: 10.1007/s10113-018-01459-3
  • Azócar, G. F., Brenning, A., & Bodin, X. (2017). Permafrost distribution modelling in the semi-arid Chilean Andes. The Cryosphere, 11(2), 877.
  • Sinclair, K. & MacDonell, S. (2016). Seasonal evolution of penitente glaciochemistry at Tapado Glacier, Northern Chile. Hydrol. Process., 30(2), 176-186.
  • Nicholson L. I., P?tlicki M., Partan B., and MacDonell S. (2016). 3-D surface properties of glacier penitentes over an ablation season, measured using a Microsoft Xbox Kinect. The Cryosphere, 10(5), 1897.
  • Arenson, L. U., Jakob, M., & Wainstein, P. (2015). Effects of dust deposition on glacier ablation and runoff at the Pascua-Lama Mining Project, Chile and Argentina. In Engineering Geology for Society and Territory-Volume 1 (pp. 27-32). Springer, Cham.
  • Abermann, J., Kinnard, C., & MacDonell, S. (2014). Albedo variations and the impact of clouds on glaciers in the Chilean semi-arid Andes. Journal Of Glaciology, 60(219), 183-191.
  • MacDonell, S., Kinnard, C., Mölg, T., Nicholson, L., & Abermann, J. (2013). Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile. The Cryosphere, 7(5), 1513-1526. http://dx.doi.org/10.5194/tc-7-1513-2013
  • Gascoin, S., Lhermitte, S., Kinnard, C., Bortels, K., & Liston, G. E. (2013). Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile. Advances in Water Resources, 55, 25-39.
  • Gascoin, S., Kinnard, C., Ponce, R., Macdonell, S., Lhermitte, S., & Rabatel, A. (2011). Glacier contribution to streamflow in two headwaters of the Huasco River, Dry Andes of Chile. The Cryosphere, (5), 1099-1113.
  • Rabatel, A., Castebrunet, H., Favier, V., Nicholson, L., & Kinnard, C. (2011). Glacier changes in the Pascua-Lama region, Chilean Andes (29 S): recent mass balance and 50 yr surface area variations.
  • Azócar, G. F., & Brenning, A. (2010). Hydrological and geomorphological significance of rock glaciers in the dry Andes, Chile (27–33 S). Permafrost and Periglacial Processes, 21(1), 42-53.
  • Nicholson, L., Marín, J., Lopez, D., Rabatel, A., Bown, F., & Rivera, A. (2009). Glacier inventory of the upper Huasco valley, Norte Chico, Chile: glacier characteristics, glacier change and comparison with central Chile. Annals of Glaciology, 50(53), 111-118.

So much sciencing!

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System change not climate change

Its one of my favourite slogans for change.

And not just because it sounds nice, but because it seems truly necessary to me. There is no solution to our ecological and well being crisis within our current mindset. In fact I find this exciting. Consider it a challenge, consider yourself having the possibility to shape a new future, downscale, readjust, take care of your own resilience and that of your community, care deeply for your local environment, and by doing so help us all.

I can strongly recommend listening to Nate Hargan talk about out how energy underpins all of our life options and societal constraints, as we operate on this planet as an energy greedy super organism. He explains how we have run up a massive debt in energy via our fossil fuel consumption during this ‘carbon pulse’ that we live in, and how this is actually an emergent behaviour of our humanity. He advocates for preparing ourselves for ‘The Great Simplification’ that must come, he believes within the coming decade. So if you want to spend a valuable hour then watch this:

As a civilisation we need to be brave enough to instigate system change to protect our environment and secure a future for all the life on our planet. We live on a limited resource planet but right now our lifestyles ignore that fact. We need a human society that reflects our existence as being from, and part of, nature not pitched against it. All our human-made systems are ours to change so lets change for the better and win our future quality of life back.

Check out: Institute for the Study of Energy and Our Future for more on the central role understanding energy plays in understanding how we got here and how to move forward, and Reality 101 to watch a condensed version of Nate Hagens university course.

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JIRP presence at the AGU meeting

Well, as part of limiting my travel I don’t usually go to the American Geophysical Union Annual Fall Meeting, but its always worth spending a little slice of time seeing what people are talking about in one of the biggest (maybe it is the biggest?) earth sciences meeting world-wide. Plus this year AGU is celebrating their 100 year anniversary, so there are some additional events and features.

The Juneau Icefield Research Program (JIRP), often encourages students to present their summer research projects at AGU. For example, in 2018 JIRP students/staff/teachers were involved in presenting 3 posters about the ice field:

This year, content from core JIRP staff and scientists is in the field of diversity and the exciting question of what the Taku glacier will do next:

Recent changes at the Taku Glacier terminus (below in 2019) can be seen in a comparison here.

Retreat Begins at Taku Glacier

The 2019 student cohort present their research project findings in team or individual posters:

And our research partners, to whom we provide logistical support present their findings in several presentations, a couple of which I have included here:

Apologies if I missed something major, but theres a lot to look through – please let me know if you have an abstract that should be linked here because its related to your activities with JIRP!

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Timelapse images of Lewis glacier

Jun Uetake (@JunUetake) of Colorado State University, has in the recent past sampled the glacier microbiology on Mt Kenya in order to compare it with the glacier microbiology in the Rwenzori. They found samples were in fact similar to microbial communities from glaciers in China and Svalbard, which is interesting in terms of global atmospheric transport of microbial communities.

Anyway while doing his research, he took hourly images of the glacier surface from near the terminus, between September 2015 and September 2016, which actually captured the splitting of the glacier into two, a process that began earlier in 2013/14. Jun sent me the time-lapse movie ages ago, but the camera angle changes party through and so just today I tried to align them best I could and make a comparison from 2015-09-21 to 2016-09-13:

2016-09-13
2015-09-21

Some of Juns papers on microbiology:

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Extending the 2-mile time machine*: where is the oldest ice?

*The title of this blog comes from the title of Richard Alleys book on ice cores called ‘The Two-Mile time machine: Ice Cores, Abrupt Climate Change, and Our Future‘, which is a great read even years after its first publication.

The oldest continuous ice core provides records of temperatures and atmospheric composition extending 800,000 years back in time. This maximum age is tantalizingly close to the time when the rhythm of the glacial-interglacial cycles on Earth changed from having a periodicity of about 40 thousand years to one of about 100 thousand years (Figure 1), the cause of which remains unresolved. So, the quest is on to find an ice core with an interpretable continuous stratigraphy extending at least 1.5 million years into the past to throw some light on what was happening to Earth’s climate during this transition.

Figure 1: The record of Pleistocene (~2.58 million years to present) glacial and interglacial cycles revealed by sea floor oxygen isotope ratios, showing the recent period dominated by 100 thousand year glacial cycles with a large amplitude, compared to the 40 thousand year cycles with lower amplitude in the early Pleistocene, that can be related to variation in the Earth’s orbit around the sun. Data replotted from Lisieki and Raymo (2005), available at: http://lorrainelisiecki. com/LR04stack.txt, with annotations in approximate positions.

What conditions preserve a continuous record to ancient ice?

Obtaining the oldest possible continuous ice core records requires knowing where on the ice sheet we can find the best preservation of the greatest number of annual accumulation layers (Figure 2). To minimize the layer disturbance caused by horizontal ice flow, ice divides are usually best for ice core sites. That aside, the age at the base of an ice core is determined by a complex interplay of total ice thickness, accumulation rate, the rate at which annual layers are progressively compressed and thinned with depth and the amount of older ice being removed by melting at the base of the ice caused by a combination of geothermal heat flux and the overburden pressure of the ice above. Clearly this is quite a lot of variables to get a handle on in a complex and remote environment.

Figure 2: A section of ice core showing the preserved annual stratigraphy. Ice core records can be analysed for time series records of air temperature, surface melt, snow accumulation, and atmospheric composition and aerosols. Photo credit: Jennie Hills.

Alternatively, it was shown in 2017 that very old ice can be found by drilling sideways into areas of so called blue ice, which is where very ancient ice is being upthrust against mountain ridges buried beneath the Antarctic ice sheet. This is well described in this cool article from that time: https://www.sciencemag.org/news/2017/08/record-shattering-27-million-year-old-ice-core-reveals-start-ice-ages but this type of coring has not yet yielded a continuous record as offered by a high quality vertical core.

How can a vertical core site be chosen?

Suitable locations for obtaining the oldest continuous ice core records are most likely to be found near previously-cored east Antarctic domes, but in areas of thinner ice where there is no basal melting (Fischer at al., 2013). However, given the financial and logistical commitments of undertaking an Antarctic drilling program, detailed reconnaissance work is required to narrow down an optimal site, and maximize the chances of a coring effort being successful. This involves examining  geophysical and glaciological data. For example, Parrenin and others 2017 identified two potential areas that could offer ice at least 1.5 million years old near the Dome C EPICA drill site using data from a dense airborne radar survey (Figure 3a), which penetrates the ice and reveals the annual accumulation layer structure of the sub-surface. Identifiable layers spanning the last ~366 thousand years were assigned ages from the well-dated EPICA core. Below these layers that have ages assigned to them, a model of annual layer thinning over time was used to extrapolate the age from the radar layers to the base of the ice sheet, accounting for heat flow and basal melt. The most promising core site locations were identified as the two areas where the modelled 1.5 million year old isochrone would be some distance above relatively invariant bedrock, where the stratigraphy is less likely to be disturbed (Figure 3b).

Figure 3: (a) Location of the surveyed area around the EPICA Dome C drilling site (red star) showing the bedrock elevation in the colour and the surface height contour lines in grey. Radar flight lines are shown in blue dots, with the transect shown in (b) highlighted in red. The labels AE indicate areas of potential old basal ice identified by a former study (Van Liefferinge and Pattyn, 2013). (b) Modeled age-depth profiles shown in colour with ice older than 1.5 Million years in white. Isochrones are highlighted as while lines, and the bedrock surface in black. The locations of the Little Dome C Patch (LDCP) and North Patch (NP) are labelled approximately in both panels. Both panels are reproduced from Parrenin and others (2017).

Looking to the future

Extracting a continuous ice core stratigraphy of temperature and atmospheric composition extending back 1.5 million years is an exciting prospect as it could not only help solve the riddle of Earth’s changing glacial heartbeat, but also provide context for discontinuous records of ancient Antarctic ice.

The ‘Beyond EPICA-Oldest Ice’ project is now in Phase II, with funding confirmed for the drilling stage which followed the site exploration of Phase I. Press releases and news from spring and summer 2019 heralded the start of the drilling part of the project, and these articles in Nature and The Guardian give a good overview. Look out for updates on their website, and in the press, as if they are successful it will no doubt be big news!

References and resources

  • Parrenin, F., Cavitte, M. G. P., Blankenship, D. D., Chappellaz, J., Fischer, H., Gagliardini, O., Masson-Delmotte, V., Passalacqua, O., Ritz, C., Roberts, J., Siegert, M. J., and Young, D. A.: Is there 1.5-million-year-old ice near Dome C, Antarctica?, The Cryosphere, 11, 2427-2437, doi:10.5194/tc-11-2427-2017, 2017.
  • Fischer, H., Severinghaus, J., Brook, E., Wolff, E., Albert, M., Alemany, O., Arthern, R., Bentley, C., Blankenship, D., Chappellaz, J., Creyts, T., Dahl-Jensen, D., Dinn, M., Frezzotti, M., Fujita, S., Gallee, H., Hindmarsh, R., Hudspeth, D., Jugie, G., Kawamura, K., Lipenkov, V., Miller, H., Mulvaney, R., Parrenin, F., Pattyn, F., Ritz, C., Schwander, J., Steinhage, D., van Ommen, T. and Wilhelms, F. (2013) Where to find 1.5 million yr old ice for the IPICS “Oldest-Ice” ice core, Climate of the Past, 9 (6), pp. 2489-250, doi: 10.5194/cp-9-2489-2013, 2013.
  • Van Liefferinge, B. and Pattyn, F.: Using ice-flow models to evaluate potential sites of million year-old ice in Antarctica, Clim. Past, 9(5), 2335–2345, doi:10.5194/cp-9-2335-2013, 2013.
  • http://www.beyondepica.eu – The ‘Beyond EPICA-Oldest Ice’ consortium
  • http://quantarctica.npolar.no – A free GIS package for Antarctica
  • http://www.antarcticglaciers.org/glaciers-and-climate/ice-cores/ice-corebasics/– Ice core Basics from Antarctic Glaciers
  • https://icecores.org/icecores/index.shtml – US National Ice Core Laboratory
  • A recent Nature News article: https://www.nature.com/articles/d41586-019-03199-8
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