Global warming cause of glacial melting and glacial floods

Posted: 20 December 2010

People in the Himalayas and other mountain areas must prepare for a tough and unpredictable future due to the rapid melting of glaciers caused by climate change, according to a new UN report.

Glaciers in Patagonia and in Alaska have been losing mass faster and for longer than glaciers in other parts of the world, according to the new report compiled by the UN Environment Programme (UNEP) in partnership with scientists world-wide including at the Norwegian Polar Institute and Norut Alta.

The third fastest rate of loss is among glaciers in the North West United States and South West Canada followed by ones in the high mountains of Asia including the Hindu Kush of the Himalayas, the Arctic and the Andes.

Overall Europe’s glaciers have been putting on mass since the mid-1970s but this trend switched in around the year 2000.

While the overall trend is down, higher levels of precipitation in some places has increased the mass and in some cases the size of glaciers including in western Norway, New Zealand’s South Island and parts of the Tierra del Fuego in South America.

Glacier cumulative mass balance
Glacier cumulative mass balance. Most mountain glaciers are losing mass, and the overall rate of mass loss has increased in the last decade. For the last decade the highest mass loss per unit area has been observed in the European Alps, Patagonia, Alaska, and north-western USA/south-western Canada.

Some mountain ranges are experiencing apparently contradictory effects. In smaller areas of the Karakoram range in Asia, for example advancing glaciers have even over-ridden areas that have been ice-free for some 50 years.

Meanwhile in northern areas of the Karakoram and the majority of Tibet, Tian Shan and Himalayas, glaciers are in fact receding – and some rapidly.

“Accumulation of science shows us a clear general trend of melting glaciers linked to a warming climate and perhaps other impacts, such as the deposit of soot reducing the reflection of heat back into space”, says UN Under-Secretary-General and UNEP Executive Director Achim Steiner. “This report underlines a global trend, observed over many decades now in some parts of the globe, which has short and long term implications for considerable numbers of people in terms of water supplies and vulnerability”.

"Without doubt the main driving force behind the rapid melting of Himalayan glaciers and formation of the catastrophic Glacial Lake Outburst Floods (GLOFs) is warming due to climate change. The risk to lives and livelihoods in the fragile Hindu Kush Himalayan region is high and getting higher. Immediate action by global community for launching long-term adaptation and resilience building programme is urgently needed,” said Madhav Karki, Deputy Director General, International Centre for Integrated Mountain Development (ICIMOD).

"These alarming findings on melting glaciers underline the importance of combating climate change globally. It sends a strong message to us as politicians and climate negotiators,” said Norway's Minister of the Environment and International Development Erik Solheim.

Glacier, Himalayas<br>&#169 DEP Kumar/UNEP/Topham
Glaciers are melting in the Himalayas
© DEP Kumar/UNEP/Topham

Mr Solheim announced in Cancun that Norway will fully fund, with more than $12 million, the five year Hindu Kush-Himalayas Climate Impact Adaptation and Assessment (HICIA) Programme from 2011.

The initiative will be carried out by the Centre for International Climate and Environmental Research, ICIMOD and UNEP-Grid Arendal.

The Norwegian Minister added: “People in the Himalayas must prepare for a tough and unpredictable future. They need our committed support. Therefore, Norway will fully fund the brand new 5-year programme. We see this programme as a potent mix of solid climate science, promising intra-regional cooperation and concrete adaptation projects on the ground. We support the programme with great enthusiasm and look forward to continued close cooperation with the program partners”.

“ICIMOD is indeed very pleased to acknowledge the generous announcement by the Royal Norwegian Government in taking a major and timely action by announcing a fresh and substantial support in launching HICIA programme," said Dr Karki.

Key findings

Melting glaciers could, in some places and perhaps in a matter of a few decades, cause a reduction in water availability in some dry areas, such as in Central Asia and parts of the Andes, says the report High Mountain Glaciers and Climate Change - Challenges to Human Livelihoods and Adaptation.

In dry regions of Central Asia, Chile, Argentina and Peru, where there is little rainfall and precipitation, receding glaciers will have much more impact on the seasonal water availability than in Europe or in parts of Asia, where monsoon rains play a much more prominent role in the water cycle.

The report says that many glaciers may take centuries to fully disappear. But underlines that many low-lying, smaller glaciers, which are often crucial water sources in drylands are melting much faster.

“When glaciers disappear, people, livestock, birds and animals will be forced to move,” says Christian Nellemann of the UNEP-GRID Arendal research centre in Norway. “But ironically, a lot of people die in deserts also from drowning, when increasingly unpredictable rains cause flash floods.”

  • Most glaciers have been shrinking since the end of the Little Ice Age around 150 years ago. However, since the beginning of the 1980s the rate of ice loss has increased substantially in many regions, concurrent with an increase in global mean air temperatures.
  • In some regions, it is very likely that glaciers will largely disappear by the end of this century, whereas in others glacier cover will persist but in a reduced form for many centuries ahead. 

As glaciers melt, lakes held back by walls of mud, soil and stones can form holding back sometimes millions of tonnes of water which can put at risk villagers and infrastructure such as power plants.

Recent flood events in the Hindu Kush-Himalaya region
Recent flood events in the Hindu Kush-Himalaya region. Since Asia comprises a large portion of the World’s population, and more than 40% of all the floods in the world occur in Asia, a large number of people are affected by disasters. In the ten-year period from 1999–2008, 402 floods were recorded in Africa, 342 in the Americas, 259 in Europe and 649 in Asia. In the same time period close to 1 billion people were affected by floods in Asia whereas the corresponding figures for Europe were around 4 million, for the Americas 28 million and Africa 22 million. The vast majority of people either injured, made homeless or otherwise affected by natural disasters on a global basis, i.e. 80–90%, live in Asia. As a rough estimate floods appear to cause 20–25% of all deaths associated with natural disasters across Asia.

In the last 40 years, Glacial Lake Outburst Floods – also known as GLOFs – have been increasing, not only in China, Nepal and Bhutan, but also more recently in Patagonia and the Andes.

  •  Five major GLOFs took place in April, October and December 2008 and again in March and September 2009 in the Northern Patagonia Icefield, Chile. On each occasion, the Cachet 2 Lake, dammed by the Colonia Glacier, released around 200 million tons of water into the Colonia River. The lake has since rapidly refilled, suggesting high risk of further GLOFs.
  • There has been a near doubling in the frequency of GLOFs in the Yarkant region of Karakoram, China, from 0.4 times annually between1959 and 1986 to 0.7 times annually from 1997-2006. This has been attributed to a warming climate.
  • In Bhutan on 7 October 1994, the glacial lake Luggye Tsho in the Lunana region, burst. The ensuing GLOF, which contained an estimated 18 million cubic metres of water, debris and trees, swept downstream killing over 20 people, and travelled over 204 km.


Boosting adaptation including reducing the risk to people, livestock and infrastructure will be increasingly important in a climate-constrained world.

In respect to melting glaciers and the formation of glacial lakes, siphoning off the water from such lakes is one adaptive action. This has been successfully carried out at lakes in the Cordillera Blanca, Peru.

Similar projects have been carried out in the Tsho and Thorthormi Glaciers in Nepal and Bhutan but the cost and technical challenges in remote locations can be high.

  • The Peruvian authorities have had substantial experience in the remediation of glacial lakes, having undertaken the first works in response to the catastrophic inundation of Huaraz in 1941, which resulted in over 5,000 fatalities.
  • Over 5000 people are killed in Asia every year by flash floods, and impacting hundreds of thousands of people in the mountain regions.

The challenge of GLOFs comes against the background of increasing concern over the impacts of extreme weather events such as flash floods on lives and livelihoods. Annually an estimated 100 to 250 million people every year are affected by flooding.

The report also calls for more investment in glacial research and monitoring. Studying and modeling the runoff from glaciers and rivers and analysing future variability linked with climate change is complex but necessary.

Mr. Steiner added: “If the world is to decisively deal with climate change, we must also address the need for programmes targeted towards adaptation strategies to build long-term resilience. Local people are already having to make tough decisions and choices as the climate around them changes. It is time for governments and the international community to step up action on cutting emissions and supporting adaptation.”. 

 Download the report here.

More information on the Hindu Kush-Himalayan Region from the International Centre for Integrated Mountain Development, ICIMOD .