Yanashallasa Glacier Retreat, Peru

Yanashallasa Glacier is near the southern end of the Cordillera Blanca in Peru. The glacier feeds the Rio Santa river, which provides irrigation for substantial agricultural acreage. Marks and Seltzer (2003) identify that at least 30% of the runoff comes from glaciers, rising considerably during the dry season. The glacier retreat in the region with a 22% area loss from 1970-2003 (Racoviteanu et al , 2008), will lead to continued decline in glacier runoff. Here we examine satellite imagery from 1992-2013 of changes in the Yanashallasa Glacier. yanas In each image the yellow dot marks the terminus, the pink arrow the same location on the west side of the glacier and the green arrow the same location on the east side of the glacier. In 1992 the terminus almost reaches a small lake beyond the glacier margin. The west margin indicates a wide connection of the glacier to slopes on the west side of the glacier. In 1999 and 2000 the glacier has retreated 150-200 m, the glacier still has a connection on the west side of the glacier. In the east side the glacier extends to the ridge east of the glacier even at the terminus. By 2013 the glacier has become disconnected from the slopes to the west of the glacier, pink arrow, the separation is a key sign of glaciers in disequilibrium. On the east side of the glacier the glacier has retreated from the east ridge at the terminus, green arrow. The losses in area along the lateral margins exceeds the retreat of the main margin, yellow dot. The main terminus retreated 250 m from 1992 to 2013. The impact of these glacier changes was assessed by USAID (2011). Other glaciers in the region are retreating in a losing mass Shallop Glacier Gurgiser et al (2013) and retreating: Quebrada Carhuascancha Glacier, Corihuasi Glacier and Chuecon Glacier in Cordillera Centrale adn Artesonraju Glacier similar fashion yanas 1992
1992 Landsat imagery

yanas 1999
1999 Landsat imargery

yanas 2000
2000 Landsat imagery

yanas 2013a
2013 Landsat imagery

yanas 2013
2013 Landsat imagery

Quebrada Carhuascancha Glacier Retreat, Peru

Quebrada Carhuascancha Glacier is in the Cordillera Blanca of Peru, draining the northeastern slopes of Huantsan. A glacier lake outburst flood was reported in the valley in 1965 from a landslide into one of the lakes. The region has experienced ongoing glacier loss with Racoviteanu et al (2008) noting a 22% loss in area from 1970-2003 in the Cordillera Blanca. They further observed an average rise of terminus elevation by 113m and an average rise in the median glacier elevation of glaciers of 66 m, with the greatest changes on the eastern side of the Cordillera. Vuille et al (2008) observed that the glacier in the Cordillera Blanca are not in balance with regional climate, and that tropical glaciers shrink in response to increased air temperature, which was the observed case in the Cordillera Blanca region. On three glaciers on nearby Nevado Queshque Marks and Seltzer (2005) observed volume loss and retreat due to warming. Examining temperature records from 29 stations in the Cordillera Blanca they found an average rising temperature trend ofof 0.26 1C per decade over the 1962-1999 period.

In this post the pink arrow notes the western margin of the lake that Carhuascancha reached in 1999 and 2000. The yellow arrow notes the terminus of the next glacier to the south of Carhuascancha, and the orange arrow a terminal-lateral moraine from the Little Ice Age. In 1999 and 2000 the glacier reaches just to the margin of the Laguna, and the southern glacier ends against a bedrock ridge. In both 2013 images Carhuascancha no longer reaches the lake terminating 250 m short of the lake and 200 m above the lake in elevation. The southern glacier terminates in a small lake that has formed. This small lake is also evident in the Google Earth imagery, which is an unknown date. Corihuasi Glacier and Chuecon Glacier in Cordillera Centrale, Yanashallasa Glacier and Artespnraju Glacier have all had a similar recent retreat. quebrada 1999
1999 Landsat image

quebrada 2000
2000 Landsat image

quebrada 2013a
2013 Landsat image

quebrada 2013
2013 Landsat image

quebrada ge
Google Earth image

Llaca Glacier Retreat, Peru

The Cordillera Blanca, Peru has 27 peaks over 6,000m, over 600 glaciers and is the highest tropical mountain range in the world. Glaciers are a key water resource from May-September in the region, Mark (2008). The glaciers in this range have been retreating extensively from 1970-2003, GLIMS identified a 22% reduction in glacier volume in the Cordillera Blanca. Vuille (2008) noted that the retreat rate has increased from 7-9 meters per year in the 1970’s to 20 meters per year since 1990. One of the glaciers that is continuing to recede is Llaca Glacier descending the west slopes of Ranralpaca. This glacier has retreated 1700 m from its Little Ice Age moraine, outlined in lime green. Llaca Laguna is impounded by this moraine. The glacier still has a significant consistent accumulation zone and can survive current climate. Stagnant pockets of debris covered ice no long connected to the glacier fill much of the valley between the laguna and the current glacier. The terminus despite ending on a steep slope lacks significant crevassing indicating a lack of vigorous flow which will lead to continued retreat of 20-30 meters per year. This glacier drains into the river which then flows into the Rio Santa in Huarez, Peru. Mark (2008)note the importance of glaciers to the Cordillera Blanca watersheds in the Huarez region receive 35% of their runoff from glaciers, and the upper Rio Santa likely receives 40%.