Climate Himalaya
June 1, 2014
This could be worrisome for Himalayan glaciers. A team from Jawaharlal Nehru University has found significantly accelerated ice melting on Chhota Shigri glacier in Lahaul and Spiti over the last 10 years. The JNU team, which has been studying the glacier for several years to understand the impact of climate change, has used meteorological data of 40 years to extrapolate the pace of ice-melt on the glacier. This is the first scientific study to have monitored a Himalayan glacier for four decades which, according to scientists, is enough time to understand the trend of glacial melt. While the Chhota Shigri glacier may give clues to glacial melt in other Himalayan glaciers, but scientists say topography and micro-climatic factors for each glacier is different.
The team from the School of Environmental Sciences, JNU, has focused on mass balance—difference of ice accumulated and lost to melting since 1969. It has divided the span of 43 years into three periods. In period I (1969-85) there was a negative mass balance and ice mass loss of 5.76 metres (water equivalent) in 16 years, in period II (1986-2000) there was status quo, but in period III (2001-12) a massive 6 metres (water equivalent) was lost in just 10 years. Over the whole modeling period the specific annual MB has been negative 60% of the time. The glacier lost about 13 metres (water equivalent) in the 43 years.
“This acceleration in ice melt in the Chhota Shigri glacier can surely be attributed to temperature rise. But the acceleration has not yet reached dangerous levels. Also, topographical factors influence glacial melt, so we cannot just say that the only reason for this kind of loss is climate change. Glaciers have their own way of balancing mass,” said A L Ramanathan, one of the authors of the study. The JNU team has its own weatherstation on Chhota Shigri glacier which has been recording weather parameters since 2009. But for this study, published in Annals of Glaciology journal recently, the team has used weather data from Bhuntar airport’s observatory close by. Chhota Shigri is at a slightly higher elevation than the airport but it can reflect the status of the glacier with a minor error margin, Ramanathan said.
The steady loss of ice mass in last 10 years was further corroborated by the team by conducting studies on ground and manually measuring ice loss annually. A team of PhD researchers from JNU visits Chhota Shigri every October. Glacial melt is of concern because of its impact on water resources. “If most of the glacial mass melts, there will be more water in the rivers for a few years but later the perennial nature of rivers will be affected. For Chhota Shigri, the entire mass or what we can call the foxed deposit has not eroded yet. But melting has accelerated,” Ramanathan added. Chhota Shigri feeds Chandra river, one of the tributaries of the Indus river system.
