Recent Trends in Melting Glaciers, Tropospheric Temperatures over the Himalayas and Summer Monsoon Rainfall over India


This report by the Division of Early Warning and Assessment (DEWA), United Nations Environment Programme (UNEP), looks at claims about climate change impacts on the Himalayas, sometimes referred to as the ‘Third Pole’ Three Indian organisations collaborated with the UNEP on this report – the Institute of Green Economy (Gurugram), The Energy Resources Institute (TERI) University (New Delhi), and Sharda University (Greater Noida).

The report summarises discussions that took place at a two-day international workshop in Delhi (December 28-29, 2009) titled ‘Emerging Issues in Climate Change – State of Tropospheric Temperature, Pollution, Melting Glaciers and their Potential Impact on Monsoon and High Altitude Vegetation in the Himalayas-Tibetan Plateau’. The workshop was attended by representatives of government, international organisations, experts, scientists, and academics.

The report has two chapters: the first looks at literature on glacial melting, while the second assesses how the Himalayas affect summer monsoon rainfall in India.

Chapter 1 says that the retreat of Himalayan glaciers has mostly been attributed to global warming. However, there is some disagreement about this, both in scientific interpretations and statistics. The chapter also has a long and detailed list of studies that provide evidence for the retreat and advance of several Himalayan glaciers.

Chapter 2 says that an increase in the concentration of aerosols over the Indian Ocean has caused a weakening of the monsoon rainfall and leads to frequent droughts in the country. However, there are other factors, such as dust mixed with soot aerosols that have advanced the monsoon rainfall to early summer.

In conclusion, the report recommends inter-country efforts to pool data in order to arrive at more reliable conclusions.    


  1. According to a July 19, 2009, article in the Times of India by journalist Nitin Sethi, Himalayan glaciers shrank by 38 per cent in 40 years.

  2. Between 1979 and 2009, there was a warming of 0.8 degree Celsius over the entire South Asian monsoon region during the month of May.

  3. India has the second largest glacier area – 23,000 square kilometres – after China, which  has 49,873 square kilometres.    

  4. The report says that China’s glaciers have been retreating since the Little Ice Age (1330-1870). However the speed of their retreat has accelerated over the past decade.

  5. The negative effects of climate change are sea level rise, ocean desalination and disruption of marine ecosystems, glacial lake floods followed by drought, unstable areas due to thawing permafrost, avalanches and landslides due to warming, threats to biodiversity, and desertification.

  6. The positive effects of climate change could be tree lines advancing to higher elevations, more land exposed for agriculture, and new ecosystems that could be beneficial to people.

  7. According to a 2009 essay in Sustainable Mountain Development No. 56, an ICIMOD (International Centre for Integrated Mountain Development) publication, monitoring the ‘terminus location’ of a glacier (usually its lower end) is neither a complete nor a comprehensive assessment of the entire glacier’s condition or health. Thus, data from the terminus location cannot adequately represent the conditions controlling the changes in volume and mass across the entire glacier system.    

  8. There are several reasons for disagreement among scientists about why Himalayan glaciers are melting, including different interpretations of what constitutes the Himalayan region and what constitutes a glacier, observations at different locations, measurements at different times of the day, season or year, and non-availability of high-resolution data.

  9. According to a 2008 essay in the journal Nature, the lack of data has been worsened by hostility between ICIMOD’s member countries – including India and Pakistan – which are reluctant to share data.

    Focus and Factoids by Harshala Chandraiah and Oorna Raut.


Division of Early Warning and Assessment (DEWA), United Nations Environment Programme (UNEP)


United Nations Environment Programme, Nairobi, Kenya


30 Dec, 2009