Himalayan glaciers ‘retreating substantially’
|
By Daniel Nelson
Most Himalayan glaciers in Bhutan, China, India and Nepal are retreating, Dr. Arun B. Shrestha, Climate Change Specialist at the Nepal-based inter-governmental regional organisation International Centre for Integrated Mountain Development (ICIMOD), told OneWorld UK and OneClimate.net this week. Shrestha’s comment comes in the wake of controversy over criticism of a claim made by the Intergovernmental Panel on Climate Change (IPCC) that Himalayan glaciers will disappear by 2035. The scientists who made the prediction in conversation with a journalist now describes it as "speculative". The controversy is one of several that has fuelled allegations by “climate change deniers” and by cautious scientists about aspects of the panel’s work. Although glacial retreat is likely to be an indication of climate change, Shrestha emphasised that the evidence for the shrinkage of glaciers is largely visual and that the only sure way of telling whether a glacier is getting smaller – whether it is losing volume – is to conduct detailed measurements of the amount of snow and ice lost and gained during the year. Shrestha confirms in the interview that lakes formed by retreating glaciers are an increasing hazard in the region. More than 200 glacial lakes are “potentially dangerous”, he says - that is, they are liable to burst. ICIMOD is “working towards” a glacial lake inventory and in the region. In terms of mountain people’s ability to adapt to changes brought about by climate change, he says, “The common observation in the Himalayas is that traditional adaptation strategies are failing in spite of constant improvisation. Rapid changes in the climate are constantly challenging people’s abilities to adapt and this may be true anywhere.” Here is the email interview in full: * What is the evidence on Himalayan glacier melt, in terms of whether glaciers are shrinking, and, if so, at what pace? Shrestha: The majority of observations on glacier fluctuation indicate that the Hindu Kush-Himalayan (HKH) glaciers are retreating substantially, especially in China, Bhutan India, and Nepal. The glaciers in the Karakorum range are also in a general state of retreat, although some of these glaciers may be advancing. Reported rates of retreat include 160 metres per year on average from 1988 to 1993 for the Luggye glacier in Bhutan; and 35 metres per year on average from 1984 to 1998, increasing to 60 metres per year between 1988 and1993 for the Raphstreng glacier in Bhutan. The valley glaciers on the right flank of the Poiqu Basin on the eastern slope of the Xixiabangma mountains in China retreated at a rate of 45-68 metres per year over the last 25 years with a 100 metre shift upslope in the elevation of the termini. The retreat rate is determined by the size and geometry of each glacier, the altitude of the glacier, and the local climatic conditions. There cannot be one representative rate for the whole region and it is not useful to try to establish a range of retreat rates or average retreat rate. * How solid is the evidence at present? Shrestha: The glacier observations in the Himalayan region are mainly based on observations of changes in terminus position (from satellite images and some ground-based observations). Terminus fluctuation is an indicator of glacier growth/shrink but is influenced by several factors. Mass balance measurements are the only way to determine whether a glacier is really losing volume. [Mass balance is the difference between the amount in water equivalent of snow accumulated, and the amount of snow and ice removed by melting.] Unfortunately, mass balance measurements in the Himalayas are rare and intermittent. Until mass balance measurements are available for a variety of glaciers at different altitudes and in different parts of the extended Himalayan ranges (east to west) it will be difficult to make a detailed or accurate scientific assessment of the extent and rate of deglaciation, or of the associated climate change factors. * How quickly could shrinking glaciers, or glacial changes, affect climate, or indeed other regional matters, such as water supply? In other words, how much do changes in glaciation matter and over what sort of time-span? Shrestha: Glaciers take some time to react to climatic perturbations. The time that a glacier takes to respond to climatic perturbation causing changes in glacial fluctuation (heating, cooling, changes in precipitation) is called the response time. Larger glaciers have a larger response time or longer time-lag; smaller glaciers respond more quickly. For large glaciers, the time-lag may be in the range of decades, while for small glaciers it may be a few years. As glaciers are storage of fresh water, glacier fluctuations are likely to have impact on water resources. However, the understanding on the present day contribution of glaciers to the runoff at small to large basin scales is not well known. Without this, it is difficult to predict extent of impacts on water resources in the future, particularly the timing at which the impact would take effect. * Are changes in glaciers the only indicators of climate change in the Himalayan region? Shrestha: Glaciers are good indicators of change, mainly because the changes are quite vivid. Beside glaciers, there are other indicators as well. Records of meteorological and hydrological variables (temperature, precipitation, river runoff, etc) are primary indicators. Biodiversity change is another important indicator. Glacial lakes are direct outcome of glacial retreat. * In general, to what extent is the issue of climate change now on ICIMOD’s agenda? When did it become a major area of concern? Shrestha: Climate change has been identified as a strategic driver in the strategic framework of ICIMOD 2007. Climate change is well placed in ICIMOD’s agenda, particularly in its new Medium Term Action Plan (MTAP) 2008-2012. The focus of ICIMOD’s climate change-related activities is to generate basic information to fill the critical gaps in scientific understanding and to pool regional and global understanding in the same. ICIMOD carries out a wide range of activities related to climate change, including the following: • Working towards generating regional baseline data, particularly on cryosphere and climate change, and developing mechanisms for sharing of data and information. The HKH region is considered as lacking the data needed to assess climate change and its impacts accurately. The problems relate both to lack of data and analyses, and to a lack of appropriate mechanisms for data and information sharing and dissemination - including, for example, lack of long-term data sets and problems with data quality. ICIMOD’s focus is on developing baseline data and information and reducing gaps and uncertainties. Recently, ICIMOD has developed the concept of using a transect approach to focus efforts for long-term monitoring. • Updating the inventory of glaciers and glacial lakes in the region and extending to other areas; detailed studies of the rate of glacier retreat and monitoring of potentially dangerous lakes in selected sub-basins; and a GLOF (glacial lake outburst flood) risk assessment, which includes state of the art field studies, and downstream impact and socioeconomic assessments. [Such floods occur when a lake contained by a glacier bursts out, as a result of erosion, a buildup of water pressure, an avalanche, an earthquake, volcanic eruptions under the ice, or if a large enough portion of a glacier breaks off and massively displaces the waters in a glacial lake at its base.] • Documenting community adaptation strategies to climate related stresses, particularly too much and too little water; assessing the vulnerability of communities with the aim of helping to build their resilience to climate related hazards developing; a climate-induced risk mapping approaches. • Activities related to REDD [Reducing Emissions from Deforestation in Forest Degradation, the forest component of international climate change negotiations]. • Carrying out an assessment of climate change vulnerability of the mountain ecosystems in the Eastern Himalayas, including an analysis of stakeholders’ perceptions of climate change; and developing plans to strengthen the transboundary landscape and corridor development process and scale up transboundary cooperation and habitat connectivity to address the challenges of conservation of biological resources and human well-being using a more community-based and integrated approach. * We have been told that the build-up of water in Himalayan mountain lakes is a potentially serious problem: if this is correct, why is it occurring? Is it a major concern? If so, have the potentially most dangerous lakes been identified? Can action be taken to limit risk to life and property? Shrestha: Glacial lakes have formed in many places in the area left at the foot of retreating valley glaciers. An inventory compiled by ICIMOD in 2001 later identified 8,790 glacial lakes within selected parts of the Hindu Kush-Himalayas. Some 204 of the glacial lakes were considered to be potentially dangerous - that is, liable to burst out leading to a glacial lake outburst flood (GLOF). There have been at least 35 GLOF events in Bhutan, China and Nepal during the 20th century. ICIMOD is working towards a second generation glacial lake inventory and regional GLOF risk assessment. ICIMOD is working on developing GLOF risk assessment methodology including field- and desk-based techniques and has tested the methodology in 4 pilot catchments in Nepal. * There is growing interest in adaptation to climate change, and historically mountain communities have shown considerable adaptive skills: do you think that lessons learned in environmental adaptation by Himalayan communities could help adaptation to climate change elsewhere in the world? Shrestha: The lessons learnt in the Himalayas through a case studies in four countries is that successful adaptation can take place only in the presence of favorable conditions. These mainly include strong institutional and policy support, social and local institutional mechanisms and good governance. Development planning must take into account climate risk with a good balance between short-term priorities and long-term gains. These messages are quite generic and applicable to any part of the world. For instance, Australia has long endured water shortage but has never faced a famine only because they have good enabling factors. However, there is a limit to how much these factors can alone contribute to adaptation. Environmental conditions need to be favorable as well. The common observation in the Himalayas is that traditional adaptation strategies are failing in spite of constant improvisation. Rapid changes in the climate are constantly challenging people’s abilities to adapt and this may be true anywhere. + Melting Himalayas - ICIMOD's comments on a turbulent debate (21 January 2010) http://www.icimod.org/?page=737 + ICIMOD's Comments to the Discussion paper, Himalayan Glaciers: A State-of-Art Review of Glacial Studies, Glacial Retreat and Climate Change (30 November 2009) http://www.icimod.org/?page=83 +Interview: Q&A: Andreas Schild and the glacial retreat debate, Surabhi Pudasaini, 21 January 2010 http://www.scidev.net/en/features/q-a-andreas-schild-and-the-glacial-retreat-debate-1.html + Hindu Kush-Himalayan Glaciers: Frequently asked questions (2009) http://books.icimod.org/index.php/search/publication/653 + The Changing Himalayas : Impact of Climate Change on Water Resources and Livelihoods in the Greater Himalayas (2009) http://books.icimod.org/index.php/search/publication/593 # |
Printable version
top of the page