Recession continues

 

These two Sentinel-2 images show changes over 4.5 years at a portion of Quelccaya's western margin. The view includes Lonnie Thompson's Base Camp (lower left) for fieldwork since the 1970s, and the marginal lake we refer to as Morojanicocha.

Some visible differences are seasonal, such as the higher water levels in May and lower-albedo ice in the ablation zone during November (also with less snowcover).

Most notable is ongoing retreat of the ice margin, particularly towards the bottom of the image where the ice is thinner. Ice is no longer calving into the lake, and our colleague Gustavo Valdivia reports that it is now possible to walk entirely around it on rock.

The importance of fieldwork

White-fronted Ground Tyrant (Muscisaxicola albifrons) with crane fly larvae and adults

Since first visiting Quelccaya in 2003, the objective of our work has been to accurately establish the summit climate, and quantitatively document how climate is recorded by the glacier - illuminating what we can learn about climate from ice cores. These efforts are documented in publications, with more still in preparation.

Working at high elevation on the glacier requires a bit of physical exertion (e.g., digging snowpits, wrestling with AWS tower extensions), as well as mental concentration (e.g., electrical wiring, datalogger programming). In spite of these requirements - or perhaps due to them - we also spend time at Quelccaya simply making observations, of both abiotic and biotic features and processes. These 'distractions' were often fascinating, including ice caves, streamflow and sediment transport, atmospheric convection, and abundant wildlife.

Our avian observations revealed behaviors previously unknown, some of which we have published (see here, here, and here), while others remain only partially understood. Another observation remained only in notes and photographs until recently, involving a fly. Since 2004, we encountered a large fly species at the AWS, typically clustered beneath the snow surface in proximity to the tower tubing and buried instrument enclosures. During transition-season visits in April and October 2014, we observed the flies on the snow surface at our moraine camp (5,200 m), crawling around in our tents, and being eaten by birds.

We posted photographs of this fly species on iNaturalist, where it remained unidentified for five years. In November, Russian entomologist Dmitry Gavryushin observed the report and took interest. He was able to identify the crane fly to species, based on a speciman from Bolivia described by prominent crane fly taxonomist Charles P. Alexander, who was affiliated with the UMass Entomology Department from 1922-1959. The coincidences continue, for the type locality for Dicranomyia (Dicranomyia) perexcelsior (Alexander) is Chacaltaya Glacier in the Cordillera Real of Bolivia. This is where Niethammer (1953) first described an association between Andean glaciers and our "Glacier Bird" (White-winged Diuca Finch; Idiopsar speculifera).

Our Quelccaya crane flies are the highest-elevation observations from anywhere in the world, which came to the attention of Pjotr Oosterbroek at the Naturalis Biodiversity Center in The Netherlands. Pjotr's enthusiasm and initiative drew in Christophe Dufour from the Muséum d’histoire naturelle in Neuchâtel, Switzerland, and resulted in our latest publication, on high-elevation crane flies. Working with these two was an absolute pleasure.

Our experience at Quelccaya demonstrates that casual observations from seldom-visited, extreme environments are often invaluable. When making them outside of one's field of expertise, one can never know just how important they might be. This is especially true during the rapid environmental changes underway. Chacaltaya Glacier, for example, no longer exists; no one will ever again observe crane flies or Glacier Birds there. Sadly, this will likely also be the case at Quelccaya before the end of the century (Yarleque et al., 2018).

 

Update (with Cranefly news)

Our AWS on Quelccaya has been decommissioned, and everything except deeply-buried tower tubing has been removed. Meteorological measurements spanning 2003 to 2018 are currently being analyzed; we welcome collaboration and data-sharing inquiries.

At least one aspect of our glacier field research will continue for another year. Also, we aspire to investigate the impact of continuing glacier recession on avian activity at Quelccaya (as reported here and here).

This week we learned more about a particular insect that was typically found at the AWS each time we visited for service and data recovery. Individuals and clusters of craneflies were observed beneath the snow surface in association with the AWS tower tubes (see above and below photos). We also observed craneflies on the snow surface near the AWS, elsewhere on the glacier, and at our glacier-margin camp. Craneflies appear to be an important food source for the many high-elevation bird species in the Quelccaya area (> 5,000m).

Cranefly photos were posted to iNaturalist after fieldwork in April 2014, seeking identification. These were identified this summer - after 6 years - based on a single specimen from Chacaltaya in Bolivia. Interestingly, this is the same location where the "Glacier Bird" (White-winged Diuca Finch, Idiopsar speculifera) was first observed in association with glaciers; Chacaltaya no longer exists.

The Quelccaya cranefly species is Dicranomyia hirsutissima. According to Pjotr Oosterbroek, author of "Catalogue of the Craneflies of the World", this is the highest known Cranefly record for all 15,000+ species found throughout the world.

This is yet another fascinating discovery from Quelccaya and the Cordillera Vilcanota, during nearly 50 years of investigation begun by Ohio State University scientists John Mercer and Lonnie Thompson.

New paper: birds & glaciers at Quelccaya

Important scientific information has been emerging from research at Quelccaya Ice Cap for nearly 50 years, from ice core records, glacial geology studies, and meteorological measurements. In recent years, research has also yielded new biological findings, revealing the importance of glaciers to the lives of birds in the High Andes.

We published a paper in 2008 documenting nesting on glacier ice at Quelccaya by White-winged Diuca-Finches. Diucas are a medium-size tanager species found in the High Andes of Peru, Bolivia, and Chile, and prior to our new publication were the only bird known to routinely build nests directly on glacier ice. This species is also among the highest-elevation nesting species in the world – to at least 5400 meters (18,000 feet) – despite an environment with average temperatures below freezing, high winds, frequent snowfall, and intense solar radiation.

Our paper in the latest Wilson Journal of Ornithology provides new details on this unique behavior. Ten years of additional observations include fieldwork at Quelccaya outside the core dry season, culminating in 2 weeks at the glacier in 2016 filming a Diuca nest with 2 chicks. Besides observations of multiple active nests, the paper also documents glacier nesting by another species, the White-fronted Ground-Tyrant, and describes nocturnal roosting within or under a glacier by 5 different species. The publication includes an online Supplement (also available here) containing additional images, and links to the BBC/PBS film.

Nesting and roosting on glaciers are adaptations to the harsh environment at high elevations in the Andes, as cavities within the ice provide both a protected microclimate and protection from predators. Are glaciers important to other species, elsewhere? What happens when the glaciers are gone, victims of climate change?

Andean glaciers are shrinking rapidly, and even the largest are likely to disappear this century. Although undocumented until only 10 years ago, the lives of several bird species appear to be dependent upon these glaciers. Their loss may have a direct, negative effect on biodiversity of the High Andes - in addition to other impacts, such as water resources.

Return from fieldwork, forthcoming papers [updated]

August fieldwork was successful and fun, despite rather unstable weather. Considerable dry-season snow blanketed south-facing slopes and the entire glacier, yet little new snow occurred during our ~10 days at Quelccaya. The panorama above shows Boulder Lake and one lobe of the glacier where we have conducted observations since 2003; Lonnie Thompson has worked here since 1974. More photos and details of recent fieldwork will be posted in the next week or two.

A variety of new papers will soon be available, so look for links on this website. As indicated below, some are closer to publication than others...

[UPDATE 10/16] Yarleque, C., M. Vuille, D.R. Hardy, O.E. Timm, J. De la Cruz, H. Ramos, and A. Rabatel. Projections of the future disappearance of the Quelccaya Ice Cap in the Central Andes. 2018. Scientific Reports. To be freely available on 22 October from Nature!

Hardy, S.P., D.R. Hardy, and K. Castañeda Gil. Avian nesting and roosting on glaciers at high elevation, Cordillera Vilcanota, Peru. Accepted 20 Aug. for Wilson Journal of Ornithology.

Hurley, J.V., M. Vuille, and D.R. Hardy. On the interpretation of the ENSO signal embedded in the stable isotopic composition of Quelccaya Ice Cap, Peru. Submitted to JGR-Atmospheres.

Yarleque, C., M. Vuille, D.R. Hardy, O.E. Timm, and H. Ramos, Future projections of precipitation variability over the eastern Central Andes. Submitted to Frontiers.

Chadwell, C.D., D.R. Hardy, C. Braun, and H.H. Brecher. Thinning of the Quelccaya Ice Cap over the last thirty years. In revision/reorganization.

Hardy, D.R., R.S. Bradley, et al. The summit climate of Quelccaya Ice Cap. In preparation.

BBC Glacier Bird filming

During our April/May 2016 fieldwork, we were joined by a BBC Natural History Unit crew. Their objective was to film White-winged Diuca Finches nesting on the glacier, a breeding behavior unknown among all other bird species. The project timing was fraught with uncertainty, for only 2 other active Diuca nests had ever been observed, and the 2015-16 El Niño event considerably impacted Quelccaya climate (overview here of a manuscript now out for review). Foremost in our minds was whether we could find active nests to film, when we arrived in April.

Fortunately, our timing was perfect; we observed all stages of breeding behavior, and successfully installed a remote camera at one of the nest sites. After a year in production the segment aired on BBC as part of an episode on the Andes, in the series Mountain: Life at the Extreme. Links to the BBC series are here and here.

This month, BBC Glacier Bird footage will premiere in the United States on PBS. The series takes a new name, Kingdoms of the Sky, with a new presenter, but otherwise appears identical: a three-part documentary "revealing the extraordinary animals and remarkable people who make a home on the iconic mountain ranges of the world - Rockies, Himalaya and Andes." The three episodes will initially air on Wednesday evenings, beginning with The Rockies on July 11 at 9 PM EDT. Himalaya premieres one week later on July 18, and Andes premieres on July 25.

The PBS series website is here, and DVDs can be pre-ordered now.

At the moment, the Glacier Bird segment can be viewed from the right-hand side of the series homepage. Click on "Meet the Bird that Nests Inside Glaciers" to see the first-ever footage of Diuca speculifera nestlings.

Even better is an 8-minute, behind-the-scenes look at Quelccaya filming, available from PBS here. Images from that clip are included above and below.

Our extended fieldwork with BBC in April 2016 was good fun, and provided new observations of Diuca and other high-elevation species. Please check our website for the Glacier Bird, and stay tuned for a new publication (still in review; contact us for a synopsis of the paper, or a pre-print).

Vilcanota wet season

Image above:  A portion of the Cordillera Vilcanota, including Nevado Ausangate (upper left), Sibinacocha (the big lake), and Quelccaya Ice Cap on 31 March 2018 (Sentinel-2 image).

Our ~15 years of measurements reveal clear relationships between ENSO and climate at Quelccaya. A detailed documentation of these is nearly ready for submission, primarily authored by collaborator John Hurley and titled "ENSO variability of Quelccaya Ice Cap d¹⁸O”

Our understanding of Quelccaya's response to ENSO will be further refined when we are able to examine accumulation resulting from the ongoing La Niña event (2017-18). Since last September, negative sea surface temperature anomalies have persisted in the east-central equatorial Pacific. These SST anomalies have been slightly more negative than last year, which followed very warm anomalies associated with the 2015-16 El Niño.

Quantifying the timing and properties of this newest accumulation cannot occur until we visit the weather station, since our data telemetry system failed in 2017. However, satellite imagery suggests that snowfall has been considerable this year. The image above provides the first relatively-clear view of the glacier and surrounding terrain in several months. In this ESA Sentinel-2 "natural-color" image (bands 4, 3, and 2), glaciers and higher peaks are entirely snow covered, and a dusting of snow is visible on terrain west and south of Quelccaya.

Greater detail can be seen in the cropped image below, showing only Quelccaya - and revealing that glacier ice is not exposed even at the lowest elevations (~5,200 m).

Finally, the GIF image at the bottom shows the Sentinel-2 EO Agriculture composite product, on approximately 1 April of the past 3 years. Note in particular the vegetation color difference between the El Niño year 2016, and the next two wet seasons during cold phase ENSO events. Also, there appears to be more snow around the glacier margin this year than in April of 2017. Our ENSO paper will document such ENSO variabilty at the summit of Quelccaya, in terms of snowfall seasonality, the vapor initial d¹⁸O values, and air temperature.

Glacier Bird on BBC

The final episode of BBC TWO's new documentary series about mountains will air at 9 pm on 13 September, featuring a variety of sequences filmed in the Andes.

Among the Andes sequences will be a segment filmed at Quelccaya, as described above. Several wonderful "behind the scenes" clips have been produced for the Glacier Bird film, one of which is here (hopefully available soon in North America). A link to the page above, with an embedded clip, is here.

Since the time of filming - just last year - science has moved forward:  we have discovered a second species of bird which also nests on the glacier (Hardy et al., submitted to Wilson Journal of Ornithology), and Glacier Bird's taxonomic classification has changed from Diuca speculifera to Idiopsar speculifer. The common name in English remains White-winged Diuca-Finch, but this too may change because the bird is not a Diuca-Finch!

For those not in the UK, the series will be broadcast in North America by PBS at a later date.

"Mountain: Life At The Extreme" (new BBC series)

On Wednesday evenings at 9 pm starting 30 August, television network BBC TWO will be airing a new 3-part documentary series exploring three different mountain ranges: the Rockies, the Himalaya and the Andes.

Each episode is more than a natural history program in that it depicts examples of both the "extraordinary animals and remarkable people" living in these extreme environments (quote credit here).

The Rocky Mountain sequences feature wolverines, extreme skier Hilaree O'Neill, big horn sheep, and Native American horse racing - among others. Clips and more are available on their website:  <http://www.bbc.co.uk/programmes/b093x4gb>

The Himalaya episode also features animals, along with the people comprising remarkable ancient cultures. One exciting sequence follows Nepali ultrarunner Mira Rai through a race. (Mira is featured in the May 2017 issue of Outside Magazine, and will be running one of the UTMB races in Chamonix this week.) For more on the episode, including clips and updated information, check the BBC website: <http://www.bbc.co.uk/programmes/b094klt5>

Details on the final episode airing 13 September have not yet being released. This post will be updated when they are - for it includes a sequence on our work at Quelccaya.

Unfortunately for North Americans, BBC TWO is not available. There will be rebroadcasts by PBS, but dates are not yet available.

Fieldwork - June 2015

Back to Quelccaya! Earlier this month we spent a couple weeks on and around the ice cap, continuing climate system research. We began the expedition as a large group with a diversity of backgrounds and interests; lots of interesting discussions ensued, while hiking and during meals. Here are some images from the adventure.

Austral winter in the Cordillera Vilcanota is typically cold and dry, with stable weather ideal for conducting fieldwork on Quelccaya. This is not how June began this year, however, as late-season snowfall during April and May continued (see 4 May entry). Here we are looking north over fresh snowcover toward Qori Kalis outlet glacier (not visible). Strong convection is already underway by 10 AM, which brought snow squalls during the afternoon. At the summit a week later we attributed ~90 cm of snow to late accumulation.

Most of the group arrived at Moraine Camp during a heavy precipitation event on the afternoon of 2 June. For more than 2 hours, large grains of graupel pelted us, driven by wind and accompanied by lightning and thunder. One lightning strike was particularly impressive (and frightening), striking a path below camp. Later we learned from our arrieros (see below) that lightning has been unusually prevalent this year, killing numerous alpaca and at least one person.

More than 40 years after his first expedition to Quelccaya Ice Cap, Lonnie Thompson was delighted to be back in 2015. Once again, he carried out a full schedule of photographing the margin, searching for old in-situ plant material emerging from beneath retreating ice, visiting Qori Kalis, and collecting snow and firn at the summit to extend his ice core record. The approach to Quelccaya is now considerably shorter than it was in 1974, yet Lonnie confirms that the partial pressure of oxygen at 5,700 m hasn't gotten any higher!

Collaborating with David Chadwell (UCSD & Scripps) we continue to quantify the magnitude of thinning at Quelccaya since 1983, when Dave worked with Henry Brecher to carefully survey the glacier. Above, Carsten Braun is making a geodetic-quality GPS measurement at one of our reference stations, prior to re-visiting numerous sites on the glacier where elevation is accurately known from the 1983-84 measurements. A manuscript detailing this work will be submitted shortly.

The majority of our time at Quelccaya was occupied by raising the AWS tower, to accommodate the summit's positive mass balance. Working together with Carsten as well as Koky Castañeda through most of 6 days we performed a complete annual service and raised everything by over 3 m. In this upward-looking view (note wind sensor), only a final trimming of guy cables and bundling of sensor leads remains to be done.

The AWS is ready for another year of measurements. One of this year's most-difficult tasks was adjusting the tower orientation to account for glacier flow. Notice how the lowest section of the tower appears tilted? It is indeed, because the tower extends another 25 m beneath the surface! Although the station is located more-or-less at the ice cap summit, where the flow vector is essentially vertical, enough differential horizontal motion has occurred since 2003 that keeping the tower plumb is not a trivial task.

Felix, Koky, and Theodoro in the snowpit, approaching 3 m depth. Here, density measurements and snow samples have been collected in the upper portion, from the shaded south-facing wall (for stable isotopes, black carbon). Just coming into view behind Theo in the deepest section is the 2014 dry-season surface. This marks the beginning of 2014-15 accumulation, and this year the 'surface' was more of a 'zone' than normal, because there was not a prolonged interval without snowfall.

Late afternoons were often spent at the glacier margin not far from camp, observing bird behavior and searching for nests used during the prior breeding season. Note the faintly-visible nest within the cavity below Koky (used by Diuca speculifera; more here). At the time this nest was occupied it was likely even more recessed from the vertical ice face, so protected from weather and relatively safe from both terrestrial predators (e.g. foxes) and from those above (e.g., Mountain Caracara, Phalcoboenus megalopterus or Aplomado Falcon, Falco femoralis).

The vicuña population near Quelccaya has increased tremendously in the past decade (Vicugna vicugna). Groups are frequently seen and heard in the area, right up to the glacier margin.

Carsten & Koky: the best!

Fieldwork for June 2015 is now complete, and prior to posting details of our largely-successful trip, I want to first acknowledge these two guys. Through two weeks of not-always-ideal weather at Quelccaya, including six trips to the summit and 6+ meters of digging, no one could ask for more competent and enjoyable assistants/companions. Carsten loves to point out that there are very good reasons why so few automated weather stations (AWS) exist in glacier accumulation zones. This is true, and the Quelccaya AWS would almost certainly not continue functioning so well - and for so long - without the involvement of these two!

The following points provide a glimpse of the critical role played by Carsten & Koky at Quelccaya, this year and in previous field seasons.

The work.  Repeatedly ascending to 5,700 meters is the fun part of our fieldwork. While at the summit - through the full spectrum of Andean winter weather - our work is strenuous and stressful. Among the tasks required in raising the entire AWS tower and electronics by 3 meters are lifting four different enclosures with >100 Ahrs of batteries, swaging dozens of cables together for structural integrity (see red tool Koky is holding), climbing and balancing on the 5 meter-tall tower while using various tools in one hand, and thinking clearly enough at 500 hPa to solve a diversity of mind-bending problems that invariably develop. In the snowpits, collecting and recording details of nearly 100 samples is laborious, while measuring density can be downright exhausting (see Snowmetrics tool Carsten is holding); for the first time, one sample this year exceeded 600 kg/m^3. Yet in all aspects of the work, these guys remain dedicated to completing every task precisely!

Being in the field.  Keeping glacier fieldwork both safe and fun is not always trivial. However, Carsten and Koky's depth of experience - and their fitness - minimize the impact of problems and discomforts which arise. Both recognize that occasional frustrations are to be expected; once challenges are overcome, they move on.  And although all of us would be perfectly happy working up there without Bob Marley, Koky's incredible music archive makes the effort a tiny bit more fun.

The science.  Science, after all, is the raison d'être for being at Quelccaya - and this is always at the forefront of our thoughts. Despite jokes about how much easier our lives would be if we had concentrated on modeling climate rather than measuring it, we are all addicted to the process of doing science in the field - reveling in the the excitement which sometimes results, and accepting the inevitable difficult and tedious moments. In reality, many aspects of the science are done either prior to fieldwork (e.g., designing and planning measurements/sampling), or upon return when data processing and sample analyses are done. During intervals of breathlessly digging snow, or gradually freezing while making motionless observations of bird behavior while they prepare to roost inside the glacier, Carsten and Koky always persist cheerfully. With fieldwork, one never knows when an unexpected situation or observation might prove valuable, whether in interpreting a landscape feature or providing insight into the various processes by which snow accumulation is transformed into a climate record. Our science benefits by having six eyes and three brains on the job!

So, Carsten and Koky once again earn a gigantic "thank you" for their efforts this year. We also thank those behind the scenes, including our entire logistics team led by Benjamin Vicencio, the creative wizardry of modelers with whom we work (M. Vuille and J. Hurley), and others who have helped to keep this project going over the years (R. Bradley, L. Thompson). Finally, we are grateful for both financial and technical support from NOAA ATDD/GCOS as well as NSF.

Ready for fieldwork!

Acclimatization has gone well, and our next round of fieldwork is about to commence. Excitement is high among our group of scientists, journalists, guides and drivers pictured above, representing 7 countries of origin. Our destination today was Cerro Wanakauri (see track here). At Quelccaya, group members this year will be pursuing a variety of objectives, from anthropology to snow chemistry to artistic photography.

October Fieldwork

This year we had an opportunity to conduct fieldwork twice:  as the 2013-14 wet season was concluding last April, and then this month just before accumulation began again. In addition to collecting data and working at the AWS, our visits bracketing the dry season were designed to investigate seasonal changes in the stable isotope composition of accumulation, as well as the extent and effects of meltwater percolation through the snowpack (i.e., mass redistribution).

Collaborating this month with Margit Schwikowski's group from PSI (Switzerland), we also drilled an ice core which will hopefully extend the 2003 ice core record of Lonnie Thompson up to the present. The team of Dr. Theo Jenk, Jogy Schindler & Reto Schild discovered that their lightweight drill was ideally suited for Quelccaya, and they established a new depth record for the equipment! Ironically, drilling was the easy part in some respects, for getting the gear in and out of Perú has required a full 2 weeks of effort by our logistics guru Benjamin Vicencio, Theo, and several diplomats. The ice is currently in a Lima freezer, but we anticipate shipment to PSI this week.

The new drilling is in support of collaboration with Mathias Vuille and John Hurley at the University at Albany, as part NSF-sponsored research examining the climatological history of the South American summer monsoon. An overview of this project is available here.

The image above was taken late in the afternoon by Reto Schild near our main camp at 5,200 m. It nicely depicts Cordillera Vilcanota weather and environment during late October this year - aspects of which will be discussed and illustrated here in greater detail. Note, for example, dramatic convection caused by increasing atmospheric instability at this time of year. The Vilcanota landscape is a mosaic of starkly contrasting environments, whose attributes were especially apparent this October; extreme 2013-14 accumulation remained on glaciers at the highest elevations, yet with longer days and higher temperatures at this time of year, considerable low-albedo ice was exposed below the transient snowline. As a result, meltwater runoff from glaciers was much greater than that of the core dry season, flooding bofedales and lakes (see image). Where present, water in this landscape supports a fascinating biodiversity, as demonstrated to us nightly by a chorus of frogs outside our tents... in sub-freezing temperatures at 5,200 meters! 

Quelccaya Ice Cap and Vilcanota glaciers are receding rapidly. With their shrinkage, water resources will decline, and lead inexorably to environmental and ecological change. Without meltwater runoff from glaciers during the dry season, the landscape will be very different, as sparse vegetation in the foreground and middle distance suggest. But while the glaciers remain, we are attempting to learn as much as possible about them, the paleoclimate archive they record, and the ecosystems they support.

Preparing for fieldwork!

A component of our forthcoming 2013 fieldwork will involve high-accuracy GPS measurements, uploading data to Scripps for processing, downloading calculated coordinates, and then re-occupying dozens of points comprising a strain net on the glacier which was established and surveyed in 1983. In preparation, Dave Chadwell & Carsten Braun are in San Diego this week testing GPS receivers, a BGAN terminal, laptops, charging systems, and Iridium phones. Multiple redundancies will hopefully insure that things go smoothly on the ice cap!

1998 snowcover from Landsat 5

Through calendar year 1998, Quelccaya was exceptionally well documented by Landsat imagery. From January into early November the ice cap is visible in almost every scene, as the satellite passed overhead every 16 days; 4 are entirely cloudless. Inspired by the Earth Observatory images of Quelccaya posted recently, collaborator Carsten Braun compiled and registered 16 scenes to demonstrate the annual cycle of accumulation and ablation at Quelccaya. These are shown below as an animated GIF cycling continuously through the 16 images, with the 1998 date shown in the upper-left hand corner.

In a year with one of the strongest recent El Niño events, the 1998 annual cycle of snowfall likely differs somewhat from a typical year. The total annual amount of snow, for example, was almost certainly below normal - although we do not have measurements from the summit that year. Nonetheless, these images nicely demonstrate the seasonality of precipitation at Quelccaya:

• In mid-January, when the wet season was well underway, the 1998 transient snowline is generally only 100-200 m higher than the ice cap margin.
• Two months later when the wet season is typically concluding, most of the glacier appears covered by snow - yet not quite to the margin and not on terrain adjacent to the ice.
• Two April images depict the greatest spatial extent of wet-season snowcover on the glacier, with thin cover on other high-elevation areas.
• By mid-May snowcover had decreased considerably, with snow present only on the glacier - and a transient snowline higher than in the mid-January image. (The 10 May image is shown above; registration issues precluded including it in the sequence below.) Snowline moves slightly higher by mid-June.
• Surprise! 27 June is well into the dry season, yet snowline reaches the lowest elevation for the year (at least to early November 1998). This scene also has the greatest spatial extent of regional snowcover for all of 1998.
  
• By the end of July almost all snow was gone from the landscape again. The transient snowline on the glacier rose continuously through July, August, and September. Very little accumulation for 1997-98 remained by the 15 September image.
• The image of 1 October shows what appears to be thin snowcover entirely blanketing the glacier. Little snow is visible elsewhere, except to the north in this image; the larger, un-cropped scene on this date shows a very different pattern of snow distribution on the landscape than after the winter (dry season) event of 27 June.
  
• By early November the next accumulation season appears to have begun, with deeper snow covering the ice cap and extended slightly beyond the margins.

Snowcover: 2010 and 2013

The previous post compared two Quelccaya satellite images discussed on NASA's Earth Observatory website. Among the many interesting features these show is the transient snowline at the time each image was acquired. Landsat images for any particular location (e.g., Quelccaya) can only be acquired when the operative satellite passes overhead, which has typically been limited to an interval of ~16 days. Useful image frequency is further limited by clouds obscuring the scene. In a recent manuscript submitted to The Cryosphere Discussions, authors Maiana Hanshaw and Bodo Bookhagen tabulate many of the best images that include Quelccaya and the Cordillera Vilcanota, beginning with those from Landsat 2 in 1975.

Our measurements on the ice cap provide a context for the 2010 EO image. The graph below shows how surface height at the summit generally decreases through the dry season. Each year of our measurements is shown in black, and for dry season dates common to all years the mean daily height is blue. Note that height decrease is not linear, which reveals important information about the processes involved!


Also shown (in red) is height through the 2010 dry season, with a pink circle indicating the EO image date. Most of the surface lowering (e.g., ablation) took place after the latest available image that year - and the 2010 dry season was the longest of our 8-year record. Before the dry season began, accumulation for the El Niño wet season 2009-10 was the lowest of our record (until this year), with maximum snowdepth reaching 1.79 m on 12 April. So, with lower than normal snowfall and a prolonged dry season - in which albedo steadily decreases - the snowline likely reached a considerably higher elevation than shown in the 2010 image, acquired two months before the dry season ended.

This year, maximum snowdepth was comparable to 2010 (1.78 m), yet reached a month earlier (18 March). A few snowfall events during April and early May have added mass, yet as of 15 May the surface is dropping below the mid-March height. This year and 2010 are the 2 lowest years of accumulation since our measurements began in 2004 (measured as snow depth, without consideration for density). For the first day of May both years, accumulation was >25 cm below the median depth (not shown in figure).

On Quelccaya this July we will measure density profiles and determine the more important measure of accumulation, which is water equivalent. If our team stays strong and our shovels don't all break, we will attempt to reach what remains of 2009-10 accumulation - assuming the 2010 snowline didn't rise above the summit!

Quelccaya from space

NASA's Earth Observatory "Image of the Day" (IOTD) has just published a pair of Quelccaya images from Landsat 5's Thematic Mapper, taken 12 years apart. Perfect registration and color correction provide a fantastic opportunity to view and explore environmental change:  click here, and then below the images click the shaded button labeled "VIEW IMAGE COMPARISON".  Now note the vertical slider bar in the image center which can be moved from side to side with the mouse to compare the scenes in 1988 and 2010.

To supplement the IOTD images and text which you just opened in another window, the following are some interpretations based on observations at the ice cap. The 2010 NASA image has been annotated with letters to show locations referenced below, and the AWS location is labeled:

A   To the east of the label, a marginal lake had just begun forming here in 1988, which gradually enlarged with ice recession. Note the thin ribbon of green extending north to the bofedal on the 1988 image; this meltwater runoff also provided water to the research camp for many years. Sometime between the 2006 and 2007 dry seasons, the lake abruptly drained subglacially into the lake below the "A" on the image, and then flooded down into the next valley to the south. Water from the glacier no longer flows past the camp, and neither a section of bofedal above the "A" nor the green ribbon are visible on the 2010 image. The bright tan-colored ribbon visible on the 2010 image below the "A" resulted from sudden drainage of the marginal lake discussed above. Water flowed under and beside the glacier into the lake (not even present in 1988) and then sloshed over a bedrock sill and cascaded as a flood to the valley below. Sediments displaced into the bofedal are visible in the image; note also that the dark-blue lake just above the North arrow has increased in size. Several lakes in this valley were cored by Meredith Kelly, Tom Lowell et al. in 2011, and the record they produce will put this event into a Holocene perspective.

B   Just north of the "B" label is Qori Kalis outlet glacier, regularly monitored by the Ohio State group (Henry Brecher & Lonnie Thompson; also see here for an dual-image comparison). With the terminus no longer in contact with the lake, the rate of ice loss due to recession has slowed - yet the glacier is rapidly thinning. On-the-ground panoramic views of the area from 2012 include Qori Kalis (here and in greater detail here) and the margin to the south (here) where on the 2010 image - just 2 years prior - this lake was barely visible.

C   This valley to the northeast of Quelccaya appears to have received increased meltwater runoff since 1988, as evidenced by the extent and saturation of green in the 2010 image (i.e., move slider back and forth to see changes). This illustrates the paradoxical impact of glacier recession on water resources: in areas of increasing melt, more meltwater reaches bofedals in the valleys below, promoting plant growth (typically water-limited here, at ~5,000 m elevation). There are a multitude of other downstream effects as well, on both natural and human systems. At some point as the glaciers continue shrinking, the enhanced runoff will begin to diminish. Note the tremendous ice loss on the ridge north of this valley!

Finally, the timeframe for this comparison must be put into context, as the dramatic changes shown by these two images span only a brief moment in the context of Earth history. Ice extent at Quelccaya has fluctuated in the past, of course, but likely never at the modern rate. For example, radiocarbon dating of plants emerging from beneath the ice near label "B" reveals a retreat rate that is nearly 2 orders of magnitude higher than the rate of advance (Thompson et al., 2013). Adapting to this rapid recession - at Quelccaya, elsewhere in the Andes, and globally - will be a major challenge for humans and all organisms dependent upon glacier meltwater runoff.

10 years for the US Climate Reference Network

Congratulations to the USCRN program on the first decade of operations!

Some of the equipment on the UMass Quelccaya weather station is compatible with that of the U.S. Climate Reference Network (USCRN), which NOAA's National Climatic Data Center (NCDC) began 10 years ago. We chose to incorporate elements of their system at our site as a result of the extensive testing and characterization they carried out. A nice overview of all USCRN aspects and prospects is contained in the Early Online Release of a paper titled "U.S. Climate Reference Network after One Decade of Operations: Status and Assessment." The paper will appear in a future issue of the Bulletin of the American Meteorological Society, and is freely available now from this link.

To stay updated on further developments of the USCRN, follow NCDC on Twitter:  @NOAANCDC