Friday, June 15, 2018
Several snowfall events during the first half of June have kept the landscape snowy at Quelccaya this year. In the 14 June image above (ESA Sentinel-2, bands 4,3,2) lingering snow is visible below 4,900 m in shaded locations.
Typically the dry season is underway by mid-June, often with snow only on the glacier. This year, the relatively-bright fresh snow is keeping the albedo low, reducing energy input and ablation of the glacier surface.
Despite the current situation, evidence indicates that recession of the ice margin is accelerating. Planning is underway for fieldwork in the next few months, when snowcover on the glacier will be measured and AWS data since July 2017 will be recovered. We're anxious to document 2017-18 La Niña accumulation!
Tuesday, May 15, 2018
Quelccaya Ice Cap currently remains largely blanketed by snowcover, excepting the very lowest ablation zone (e.g., Qori Kalis outlet glacier). The GIF above contains only 2 images; the snowy scene without red annotation was acquired last week (10 May 2018). Contrast 2018 snowcover on the glacier with that 2 years earlier, at the end of March 2016.
These images show a portion of the ice cap's western margin. We have visited this area at least annually since 2003, witnessing continuous retreat of the margin and changes in all of these proglacial lakes.
The red ellipses on the 2016 image highlight two areas where margin retreat is clearly evident. Our GPS measurements up through 2017 at the lower section indicate a retreat rate of 10-15 m/year. At the small red circle by the larger lake, the area of bedrock near the circle has expanded, and only a small portion of the glacier still extends into the lake (contrast 2013). Throughout our years of fieldwork in the area we have observed ice calving into this lake, which began forming in ~1985 (Thompson et al., 2013). Within the next year or two the glacier will no longer reach the lake.
One consequence of Quelccaya margin retreat and thinning is loss of suitable nest sites for the "Andean Glacier Bird" (White-winged Diuca-Finch, Idiopsar speculifer; formerly Diuca speculifera). Until the mid-2000s the area near the lower ellipse supported a relatively high density of nests, built directly on the ice (Hardy and Hardy, 2008 and here). As ice at this margin thinned and became less steep, the area was abandoned for nesting. More recently, the area near the small circle has been used for nesting (e.g., 2014 oblique photo of margin at the lake), but as the ice becomes thinner the birds will need to move up in elevation to find suitable, steep ice slopes. Furthermore, the Glacier Bird is not the only bird species impacted by ice recession; a new manuscript detailing this is currently in review (and available upon request).
Ref: Thompson, L.G., E. Mosley-Thompson, M.E. Davis, V.S. Zagorodnov, I.M. Howat, V.N. Mikhalenko, and P.-N. Lin. 2013. Annually resolved ice core records of tropical climate variability over the past ~1800 years. Science, vol. 340, 945-950. 10.1126/science.1234210
Tuesday, April 3, 2018
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.
Tuesday, November 21, 2017
Friday, September 8, 2017
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.
Tuesday, August 29, 2017
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.
Tuesday, August 15, 2017
We visited Quelccaya for fieldwork during July this year and experienced a long interval of sunny, dry weather. Although July is solidly within the core winter dry season, the atmosphere was particularly dry at this time; the cloud visible in the background above was literally the largest we saw during our time at the ice cap.
Below are two oblique views of the glacier margin, on the day that we arrived in the area (20 July) and the day we departed (27 July). Due to funding constraints, this was a relatively short trip. After 8 days of clear sky and intense solar radiation, some might expect to see more change in the transient snowline than the images show. In other years of fieldwork this has certainly been the case. This year, the areas of greatest apparent change over the interval are highlighted by the red ellipses. Although these areas were determined subjectively from the images, rather than measurements of snow depth, two clear-sky satellite images roughly bracketing the period reveal a similar pattern (see below).
Why so little ablation of snow, within a zone which is both thinning and retreating rapidly in recent decades? Most likely, this was due to the combination of dry atmosphere and low wind speed during this interval. With a negative vapor pressure gradient due to the dry air, any available energy went toward sublimation, requiring ~8 times more energy per kilogram than melting. Furthermore, low wind speed suppressed turbulent transfer of latent heat. At the summit, relative humidity was typically ~10 percent (vapor pressure <2 hPa) and rarely rising to 50 percent during the afternoons.
Despite little ablation during this brief interval of the dry season, recession of the ice cap in this area is accelerating. A subsequent post and paper will quantify retreat we have been measuring since 2008, revealing the profound changes associated with the 2015-16 El Niño event.