Nature        DOI: 10.1038/nature11324

Contrasting patterns of early twenty-first-century glacier mass change in the Himalayas

Andreas Kääb (Oslo), Etienne Berthier (Toulouse), Christopher Nuth (Oslo), Julie Gardelle & Yves Arnaud (Grenoble)

Contact: A. Kääb, kaeaeb@geo.uio.no, +47 22855812,  http://folk.uio.no/kaeaeb


 

Additional Material

Available photos and figures (details and full-resolution images below):
          


Links:
 
NASA ICESat webpage (webpage of the space instrument used for the study)
ESA Climate Change Initiative (webpage of the study sponsor)





Ngozumpa Glacier, Everest region, Nepal. Kangtega (6779 m asl.) and Thamserku peaks in the background. One of the major outcomes of the study is that debris-covered glaciers shrink on total at a similar rate than clean-ice glaciers, despite of the insulating effect of debris covers. The rough topography of Ngozumpa Glacier, covered by numerous melt lakes, illustrates this ice wastage.

Photo taken end of November 2009 by Kimberly Casey

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Ngozumpa Glacier, Everest region, Nepal. Cho Oyu peak (8201 m asl.) in the background. One of the major outcomes of the study is that debris-covered glaciers shrink, despite of the insulating effect of debris covers, at a similar rate than clean-ice glaciers. The rough topography of Ngozumpa Glacier, covered by numerous melt lakes, illustrates this rapid ice wastage through thermokarst processes. 

Photo taken end of November 2009 by Kimberly Casey

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Ngozumpa Glacier, Everest region, Nepal. Gyachung Kang peak (7952 m asl.) in the right background. One of the major outcomes of the study is that debris-covered glaciers shrink, despite of the insulating effect of debris covers, at a similar rate than clean-ice glaciers. The rough topography of Ngozumpa Glacier, illustrates this rapid ice wastage through thermokarst processes. 

Photo taken end of November 2009 by Kimberly Casey

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Ice pinnacles on Khumbu Glacier, Everest region, Nepal.

Photo taken end of November 2009 by Kimberly Casey

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Khumbu ice fall, Khumbu Glacier, near the Everest Base Camp. Mt. Everest peak (8848 m asl.) in the upper right background, mostly hidden by its west shoulder.

Photo taken end of November 2009 by Kimberly Casey

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Mt. Everest (left), Nuptse (middle), Lhotse (right).

Photo taken end of November 2009 by Kimberly Casey        


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Mt. Everest (left), Nuptse (right)

Give '(c) Etienne Berthier' when used


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Mt. Everest (left), Nuptse (middle)

Give '(c) Etienne Berthier' when used


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Mt. Everest and Nuptse in the left background.

Give '(c) Etienne Berthier' when used


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Mt. Everest

Give '(c) Etienne Berthier' when used


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Inkhu Glacier.

Give '(c) Patrick Wagnon - IRD' when used


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Inkhu Glacier with Makalu peak (8481 m asl.) in the left background

Give '(c) Patrick Wagnon - IRD' when used


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Synthetic views on Mt. Everest. Red dots indicate all autumn ICESat laser tracks in the area from 2003 to 2008. The footprints shown have roughly the size of the real footprints of individual laser shots: every ICESat track consists of a profile of laser footprints, each of 70m diameter (for which the average elevation is computed), with a distance of 170m between the individual footprints. The background satellite image stems from the ASTER sensor onboard the NASA Terra spacecraft, showing vegetated areas in red tones. The terrain over which the satellite image and the laser footprints are rendered is taken from the Shuttle radar topography mission.

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The study is based on measurements from the ICESat satellite. How does ICESat work?

ICESat sends laser pulses from a 600 km orbit to the Earth surface where they are reflected back to the satellite. The travel time for each laser pulse down to Earth and back is precisely measured and converted to the distance between satellite and Earth surface (A in the figure). As the elevation of the satellite orbit (B) is also known very precisely, the Earth surface elevation C can be computed for every laser shot. These shots illuminate a circle of 70m diameter and have a spacing of 170m along the satellite track. Such measurements were repeated from 2003 to 2009 and gave year-to-year glacier thickness changes over almost 6 years. 

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All autumn ICESat laser footprints from 2003 to 2008 over the Mt. Everest area used for the study as KMZ or KML file. Within GoogleEarth or similar tools, these footprints can be vizualized such as in the examples to the left.

Download the file everest_small.kmz (small symbols) or everest_large.kmz (large symbols) and open it in, for instance, GoogleEarth.

Alternatively you can download everest.kml and symbol.png to the same folder, and replace the image symbol.png with any other symbol for the footprints. Any new symbol has to be in .png format and have the filename 'symbol.png'.





Map over the Himalayas with all ICESat laser tracks and footprint locations used in the study

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Study region and glacier elevation trends from ICESat laser altimetry over 2003–2008. Each data circle indicates the elevation trend averaged over an area of 2 deg latitude x 2 deg longitude. The more red the fillings the thinner got the glaciers within a 2x2 deg cell. Blue fillings indicate glacier thickening.
The size of each circle indicates the accuracy of elevation trends for each 2x2 deg cell. The larger a circle the more accurate the elevation trend, which its colour indicates. The mean trends for each sub-region (Hindu Kush to Eastern Nepal/Bhutan) are given in metres
per year. Only ICESat tracks and footprints over glaciers are indicated.

Modified after Fig.1 in original Nature publication.

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Median elevation differences and trends between ICESat laser altimetry (years 2003-2009) and the SRTM radar elevation model (year 2000). For off-glacier terrain (black triangles and curves) all medians are shown; for glaciers only autumn laser altimetry periods (red dots and dashed curves) are shown. Autumn trends (red bold lines) are fitted through all around 80,000 individual elevation differences using a robust fitting method, not through the laser altimetry medians.
The total vertical offset between off-glacier (black) and glacier curves (red) is due to variable penetration depths of the radar waves used for the SRTM elevation measurements into snow and ice. This vertical offest, i.e. penetration depth of up to several metres, is largest for Karakoram. 
  

Modified after Fig.2 in original Nature publication.

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Himalaya and Tibet plateau. All ICESat laser tracks and footprint locations (red) over the Himalayas used in the study

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