According to the findings of International Centre for Integrated Mountain Development (ICIMOD) Himalayas glacier retreat rates between 1980 and 1990 were double of those observed in later decades, and it requires further investigation.
On 15 May 2014, at the closing of the second international conference on ‘Cryosphere of the Hindu Kush Himalayas: State of Knowledge’, the International Centre for Integrated Mountain Development (ICIMOD) released a publication titled ‘Status and Decadal Glacier Change from 1980s to 2010 in Nepal based on Satellite Data’. The report, primarily an inventory of glaciers in Nepal, drew significant interest from media, both local and international. However, some news reports cited inaccurate data while others suggested a link between climate change and increased avalanche activity in the Himalayas (here and here). Therefore, we would like to make three major clarifications.
First, the report on decadal glacier change in Nepal does not discuss the link between climate change and increased avalanche activity. It presents the results of satellite-derived decadal glacier inventories (1980, 1990, 2000, and 2010) for major river basins of Nepal and examines changes in glaciers between these intervals. The results indicated shrinkage in glacier area in all three decades, and an increase in the number of glaciers due to retreat and separation. A widely circulated news article switched the number of glaciers in 1980 and 2010 (here) and mistakenly reported estimated ice reserves in cubic meters instead of cubic kilometers.
Second, the terminology in the news reports that link avalanches to climate change is ambiguous. The word ‘avalanche’ typically refers to a mass movement of snow down a sloping surface. An avalanche requires a snowpack of sufficient depth with a weak layer, a sufficiently steep slope, and a trigger. In contrast, the 18 April tragedy on Mount Everest was the result of a different phenomenon called serac collapse. Seracs are large blocks of ice that are formed as a result of glacier fracture patterns and motion, and can fall or topple without warning. The normal climbing route on Everest between Base Camp and Camp 1 is exposed to serac hazards from the Khumbu Icefall and from both the south face of Everest and the north face of Nuptse. The risk varies from year to year depending on the state of the seracs. Changes in the frequency of either avalanches or serac falls in the Everest region have not been definitively linked to climate change.
Finally, the reported estimates of glacier retreat of nearly 25% since 1977 should also be treated with a degree of caution. The executive summary of the report suggests that glacier retreat rates between 1980 and 1990 were double of those observed in later decades, and that this warrants further investigation. It is likely that the misclassification of snow as glacier ice in the 1980 inventory, particularly at middle and higher elevations has resulted in the overestimation of ice loss.
On 15 May 2014, at the closing of the second international conference on ‘Cryosphere of the Hindu Kush Himalayas: State of Knowledge’, the International Centre for Integrated Mountain Development (ICIMOD) released a publication titled ‘Status and Decadal Glacier Change from 1980s to 2010 in Nepal based on Satellite Data’. The report, primarily an inventory of glaciers in Nepal, drew significant interest from media, both local and international. However, some news reports cited inaccurate data while others suggested a link between climate change and increased avalanche activity in the Himalayas (here and here). Therefore, we would like to make three major clarifications.
First, the report on decadal glacier change in Nepal does not discuss the link between climate change and increased avalanche activity. It presents the results of satellite-derived decadal glacier inventories (1980, 1990, 2000, and 2010) for major river basins of Nepal and examines changes in glaciers between these intervals. The results indicated shrinkage in glacier area in all three decades, and an increase in the number of glaciers due to retreat and separation. A widely circulated news article switched the number of glaciers in 1980 and 2010 (here) and mistakenly reported estimated ice reserves in cubic meters instead of cubic kilometers.
Second, the terminology in the news reports that link avalanches to climate change is ambiguous. The word ‘avalanche’ typically refers to a mass movement of snow down a sloping surface. An avalanche requires a snowpack of sufficient depth with a weak layer, a sufficiently steep slope, and a trigger. In contrast, the 18 April tragedy on Mount Everest was the result of a different phenomenon called serac collapse. Seracs are large blocks of ice that are formed as a result of glacier fracture patterns and motion, and can fall or topple without warning. The normal climbing route on Everest between Base Camp and Camp 1 is exposed to serac hazards from the Khumbu Icefall and from both the south face of Everest and the north face of Nuptse. The risk varies from year to year depending on the state of the seracs. Changes in the frequency of either avalanches or serac falls in the Everest region have not been definitively linked to climate change.
Finally, the reported estimates of glacier retreat of nearly 25% since 1977 should also be treated with a degree of caution. The executive summary of the report suggests that glacier retreat rates between 1980 and 1990 were double of those observed in later decades, and that this warrants further investigation. It is likely that the misclassification of snow as glacier ice in the 1980 inventory, particularly at middle and higher elevations has resulted in the overestimation of ice loss.
