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The Changing Himalayas
The Changing Himalayas
Impact of climate change on water resources and livelihoods in the greater Himalayas
Mats Eriksson, Xu Jianchu, Arun Bhakta Shrestha, Ramesh Ananda Vaidya, Santosh Nepal, Klas Sandström
Summary: The greater Himalayan region “the roof of the world” – contains the most extensive and rugged high altitude areas
on Earth, and the largest areas covered by glaciers and permafrost outside the polar regions. The water resources from this area
drain through ten of the largest rivers in Asia, in the basins of which more than 1.3 billion people find their livelihoods. The region
and its water resources play an important role in global atmospheric circulation, biodiversity, rainfed and irrigated agriculture,
and hydropower, as well as in the production of commodities exported to markets worldwide. The water resources of this region
are currently facing threats from a multitude of driving forces. Global warming is having a severe impact on the amount of snow
and ice, which has serious implications for downstream water availability in both short and long term as up to 50% of the average
annual flows in the rivers are contributed by snow and glacial melting. The warming in the greater Himalayas has been much
greater than the global average: for example, 0.6 degrees Celsius per decade in Nepal, compared with a global average of
0.74 degrees Celsius over the last 100 years. Changes in precipitation are ambiguous with both increasing and decreasing
trends in different parts of the region. The most serious changes are probably related to the frequency and magnitude of extreme
weather events, such as high intense rainfalls leading to flash floods, landslides and debris flows. There is a severe gap in the
knowledge of the short and long-term implications of the impact of climate change on water and hazards in the Himalayas, and
their downstream river basins. Most studies have excluded the Himalayan region because of its extreme and complex topography
and the lack of adequate rain gauge data. There is an urgent need to close the knowledge gap by establishing monitoring
schemes for snow, ice, and water; downscaling climate models; applying hydrological models to predict water availability; and
developing basin wide scenarios which also take water demand and socioeconomic development into account. Climate change
induced hazards such as floods, landslides, and droughts will impose significant stresses on the livelihoods of mountain people
and downstream populations. Society will need to improve its adaptation strategies, and level structural inequalities that make
adaptation by poor people more difficult. It is important to strengthen local knowledge, innovations, and practices within social
and ecological systems as well as strengthening the functioning of institutions relevant for adaptation. Sound science together with
credible, salient, legitimate knowledge is important to support the development and implementation of sound policies.
growing international importance, and a rapid reduction
in poverty. China and India are also the two leading
The Region
producers of rice in the world, most of the harvest coming
The ‘greater Himalayan region’, sometimes called
from irrigated agriculture in the Ganges, the Yangtze, and
the ‘Roof of the World’, is noticeably impacted by
the Yellow River basins. However, as noted in the Stern
climate change. The most widely reported impact is the
Report on ‘The Economics of Climate Change’, “China’s
rapid reduction in glaciers, which has profound future
human development could face a major ‘U-turn’ by this mid-
implications for downstream water resources. The impacts
century unless urgent measures are now taken to ‘climate
of climate change are superimposed on a variety of other
proof’ development results” (Stern 2006).
environmental and social stresses, many already recognised
Continuing climate change is predicted to lead to major
as severe (Ives and Messerli 1989).
changes in the strength and timing of the Asian monsoon, inner
The ‘Roof of the World’ is the source of ten of the largest
Asian high pressure systems, and winter westerlies – the main
rivers in Asia (Table 1). The basins of these rivers are
systems affecting the climate of the Himalayan region. The
inhabited by 1.3 billion people and contain seven
impacts on river flows, groundwater recharge, natural hazards,
megacities. Natural resources in these basins provide
and the ecosystem, as well as on people and their livelihoods,
the basis for a substantial part of the region’s total GDP
could be dramatic, although not the same in terms of rate,
and important environmental services, which are also of
intensity, or direction in all parts of the region. Given the
importance beyond the region (Penland and Kulp 2005;
current state of knowledge about climate change, determining
Nicholls 1995; Woodroffe et al. 2006; Niou 2002; She
the diversity of impacts is a challenge for researchers, and risk
2004; Macintosh 2005; Sanlaville and Prieur 2005).
assessment is needed to guide future action.
China and India are today experiencing economic growth,
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