Scientists from around the world have assessed the planet’s 78 mountain glacier–based water systems and, for the first time, ranked them in order of their importance to adjacent lowland communities, as well as their vulnerability to future environmental and socioeconomic changes. These systems, known as mountain water towers, store and transport water via glaciers, snow packs, lakes and streams, thereby supplying invaluable water resources to 1.9 billion people globally—roughly a quarter of the world’s population.

The research, published in the prestigious scientific journal Nature, provides evidence that global water towers are at risk, in many cases critically, due to the threats of climate change, growing populations, mismanagement of water resources, and other geopolitical factors. Further, the authors conclude that it is essential to develop international, mountain-specific conservation and climate change adaptation policies and strategies to safeguard both ecosystems and people downstream.

Globally, the most relied-upon mountain system is the Indus water tower in Asia, according to their research. The Indus water tower—made up of vast areas of the Himalayan mountain range and covering portions of Afghanistan, China, India and Pakistan—is also one of the most vulnerable. High-ranking water tower systems on other continents are the southern Andes, the Rocky Mountains and the European Alps.

To determine the importance of these 78 water towers, researchers analyzed the various factors that determine how reliant downstream communities are upon the supplies of water from these systems. They also assessed each water tower to determine the vulnerability of the water resources, as well as the people and ecosystems that depend on them, based on predictions of future climate and socioeconomic changes.

Of the 78 global water towers identified, the following are the five most relied-upon systems by continent:

  • Asia: Indus, Tarim, Amu Darya, Syr Darya, Ganges-Brahmaputra
  • Europe: Rhône, Po, Rhine, Black Sea North Coast, Caspian Sea Coast
  • North America: Fraser, Columbia and Northwest United States, Pacific and Arctic Coast, Saskatchewan-Nelson, North America-Colorado
  • South America: South Chile, South Argentina, Negro, La Puna region, North Chile

The study, which was authored by 32 scientists from around the world, was led by Prof. Walter Immerzeel (Utrecht University) and Dr. Arthur Lutz (Utrecht University and FutureWater), longtime researchers of water and climate change in high mountain Asia.


The SREB is part of the Belt and Road Initiative, being a development strategy that focuses on connectivity and cooperation between Eurasian countries. Essentially, the SREB includes countries situated on the original Silk Road through Central Asia, West Asia, the Middle East, and Europe. The initiative calls for the integration of the region into a cohesive economic area through building infrastructure, increasing cultural exchanges, and broadening trade. A major part of the SREB traverses Asia’s high-altitude areas, also referred to as the Third Pole or the Asian Water Tower. In the light of the planned development for the SREB traversing the Third Pole and its immediate surroundings, the “Pan-Third Pole Environment study for a Green Silk Road (Pan-TPE)” program will be implemented.

The project will assess the state and fate of water resources in the region under following research themes:

1. Observed and projected Pan-TPE climate change
2. Impacts on the present and future Water Tower of Asia
3. The Green Silk Road and changes in water demand
4. Adaptation for green development

Hasta el momento no existe una metodología ampliamente aceptada para cuantificar el impacto del riesgo climático en proyectos de recursos hídricos que son apoyados y financiados por el Grupo del Banco Mundial. El Grupo de Evaluación Independiente (IEG) en su informe de 2012 titulado «Adaptación al clima Cambio: Evaluar la experiencia del Grupo del Banco Mundial», reconocía que «los modelos climáticos han sido más útiles para establecer el contexto que para informar de las mejores opciones de decisión política y de inversión” y que «a menudo tienen un valor agregado relativamente bajo para muchas de las aplicaciones descritas». En el informe se reconoce que «aunque el sector hidroeléctrico tiene una larga tradición para gestionar la variabilidad climática, el Grupo del Banco carece de herramientas de orientación específica y de metodologías apropiadas para incorporar las consideraciones del cambio climático en el diseño y la evaluación de los proyectos hidroeléctricos».

Tras su publicación en 2015 («Confrontando la incertidumbre climática en la planificación de recursos hídricos y el diseño de proyectos: El marco del árbol de decisiones»), el DTF se ha aplicado a diferentes proyectos del Banco en seis casos piloto de diferente índole (generación hidroeléctrica, suministro de agua, y riego) y financiado con fondos del Water Partnership Program. Este esfuerzo continúa en el marco de este análisis para dos proyectos adicionales que reciben financiación del Fondo Fiduciario para el Crecimiento Verde de Corea (KGGTF) y que se centran en aumentar la resiliencia y seguridad hídrica frente a inundaciones y el aumento del riego en la cuenca del río Nzoia en Kenia, y en la aplicación de la Guía de Resiliencia Climática del Sector Hidroeléctrico, basada en el DTF, para la central hidroeléctrica de pasada de Kabeli-A en Nepal.

FutureWater contribuye al proyecto mediante la ejecución de tareas específicas encaminadas a evaluar el riesgo de ambos proyectos mediante la modelización de cultivos y de asignación de agua en el caso de estudio de Nzoia, y la modelización hidrológica para cuencas de alta montañas en el caso de estudio de Nepal.

HI-AWAREHI-AWARE is one of four consortia of the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA). HI-AWARE aims to contribute to enhanced adaptive capacities and climate resilience of the poor and vulnerable women, men, and children living in the mountains and flood plains of the Indus, Ganges, and Brahmaputra river basins through the development of robust evidence to inform people-centred and gender-inclusive climate change adaptation policies and practices for improving livelihoods.

HI-AWARE will:

  • Generate scientific knowledge on the biophysical, socio-economic, gender, and governance conditions and drivers leading to vulnerability to climate change;
  • Develop robust evidence to improve understanding of the potential of adaptation approaches and practices, with an explicit focus on gender and livelihoods;
  • Develop stakeholder-driven adaptation pathways based on the up- and out-scaling of institutional and on-the-ground adaptation innovations;
  • Promote the uptake of knowledge and adaptation practices at various scales by decision-makers and citizens; and
  • Strengthening the interdisciplinary expertise of researchers, students, and related science-policy-stakeholder networks.

HI-AWARE study sites

HI-AWARE will focus its activities in 12 sites, representing a range of climates, altitudes, hydro-meteorological conditions, rural-urban continuum, and socio-economic contexts in four study basins: the Indus, Upper Ganga, Gandaki and Teesta. It will conduct research in these sites, including modeling, scoping studies, action research, and randomized control trials. It will test promising adaptation measures in observatory labs at the sites for out-scaling and up-scaling. It will also conduct participatory monitoring and assessment of climate change impacts and adaptation practices to identify:

  • Critical moments – times of the year when specific climate risks are highest and when specific adaptation interventions are most effective;
  • Adaptation turning points – adaptation turning points – when current policies and management practices are no longer effective and alternative strategies have to be considered; and
  • Adaptation pathways – sequences of policy actions that respond to adaptation turning points by addressing both short term responses to climate change and longer term planning.

FutureWater’s main tasks focus on biophysical drivers and conditions leading to vulnerability to climate change. Key tasks are to:

  • Develop detailed mountain specific and basin scale climate change scenarios;
  • Improve cryosphere-hydrological modeling to assess significant shifts in flow regimes with an aim to develop water demand and supply scenarios as well as improve and apply water-food impact models; and
  • Better understand climate change impacts on extremes (heat, floods, drought),and quantify these extremes from climate models and subsequently impact models.

Warming of the climate system is unequivocal. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased. The Himalayan region (after Antarctica and the Arctic) has the third largest amount of ice and snow in the world, and is exceptionally vulnerable. The various Global Climate Models (GCM) predict very similar future temperature trends for the region, but projections of future precipitation patterns differ widely. As a consequence, the need for increased knowledge about future climate change remains high. The main focus of GCMs thus far was on temperature increases and potential changes to the hydrological cycle. The overall tendency that has emerged is that wetter regions are likely to become wetter and drier regions drier. Increased scientific knowledge, coupled with recent weather events, show that changes in hydrological extreme events can be substantial and the geographical and temporal resolution of predicted changes remains low in many areas.

For Statkraft, as the largest generator of renewable energy in Europe and a leading company in hydropower internationally, an understanding of future changes to the hydrological cycle and its uncertainty is crucial for effective business planning. Investment decisions regarding the business strategy for the next 50 years depend on accurate predictions of climate change impacts on inflow over that period.  In addition, changing probabilities and magnitudes of extreme events can put additional risk on infrastructure (dams and hydropower plants) or on other crucial infrastructure (roads and transmission lines).  Statkraft’s intention to grow in the region makes it necessary to assess short, medium and long-term impacts, risks and opportunities resulting from climate change, to ensure sustainable management of the water resources for all stakeholders. Currently, Statkraft’s main business focus lies with northern India (mainly the state of Himachal Pradesh) and Nepal, while Bhutan and Myanmar might be areas of future business development as well.

Kaligandaki Hydro power located in Nepal.

Through the International Centre for Integrated Mountain Development (ICIMOD), the inter-governmental learning and knowledge sharing Centre serving the eight regional member countries of the Hindu Kush Himalayas (HKH), FutureWater provided a comprehensive review study on climate change and the impacts on cryosphere, hydrological regimes and glacier lakes in the Indus, Ganges, and Brahmaputra river basins. This review study was done in the context of future hydropower development in the region.

The climate, cryosphere and hydrology of the Hindu-Kush Himalaya (HKH) region have been changing in the past, and will continue to change in the future; warming of the climate system is unequivocal. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased. The Himalayan region has the third largest deposit of ice and snow in the world, after Antarctica and the Arctic and might be exceptionally vulnerable. There is good agreement among Global Climate Models (GCM) on future temperature trends in the region, but projections of future precipitation patterns differ widely. As a consequence, the demand for increased knowledge about future climate change is still high. A main focus has been given to temperature increases and changes to the hydrological cycle with the tendency that wetter regions mainly will become wetter and drier regions will become drier. Growing scientific knowledge and recent weather events show that extremes related to hydrological changes can be substantial though and the geographical and time-wise resolution of predicted changes is still low in many areas.

Energy is one of the major drivers of changes in the HKH region. The region has a high potential for hydropower due to abundance of water in conjunction with verticality of landscape. However, the changing climate and hydrological regime might pose a risk to hydropower development in the future. It has become imperative for hydropower developers to have a good understanding about the changes in the hydrological cycle and its uncertainty. Also, changing probabilities and magnitudes of extreme events can put additional risk on hydropower infrastructures.

Hydropower projects in Nepal according to the Department of Electricity as of 16 March 2015. The Tamakoshi basin is indicated by the blue boundary.
Hydropower projects in Nepal according to the Department of Electricity as of 16 March 2015. The Tamakoshi basin is indicated by the blue boundary.

The overall objective of this project is therefore to improve the understanding of the expected impacts of climate change on water availability in the context of potential hydropower development in the Tamakoshi River Basin. Specifically, the project aims to:

  • Understand the current baseline hydrological regime of the Tamakoshi River Basin
  • Develop detailed climate change projections for the 21st century, including factors relevant for hydropower development
  • To understand the future hydrology and its potential impact on the hydropower potential

Global warming is considered as one of the major threats for the world’s population and coping with it may be one of the largest challenges for this century. Multiple attempts to streamline global policy on climate change mitigation have been made over the past decades, and the “Paris Agreement” which was signed at the 21st Conference of the Parties in 2015 is considered a major breakthrough in formulating adequate measures to tackle climate change. Governments agreed on “a long-term goal of keeping the increase in global average temperature to well below 2°C above pre-industrial levels”, and “to aim to limit the increase to 1.5°C, since this would significantly reduce risks and the impacts of climate change”. In response to this development, the Intergovernmental Panel on Climate Change (IPCC) will publish a Special Report on global warming of 1.5 °C above pre-industrial levels, and is gathering scientific content for this report.

Flooding in Bangladesh.

However, scientific evidence of the impacts of a 1.5 ˚C global warming, and more importantly, the differences in impacts between a 1.5 ˚C and a 2 ˚C global warming, is lacking. Therefore, the scientific community has been mobilized to provide this scientific evidence as input to the special report. FutureWater leads a regional assessment quantifying the impacts of a 1.5 ˚C versus a 2 ˚C global warming for a major global climate change hotspot: the Indus, Ganges and Brahmaputra river basins in South Asia.

Water is becoming an increasingly critical factor in Asia. The catchments of Hindu – Kush Himalayan (HKH) are a source of a significant portion of this water. Glaciers are a component of the HKH water budget. There is general agreement that a widespread retreat of the global ice cover has been occurring since at least the late 1800s. However, a consensus view of the significance of this retreat in terms of factors determining glacier mass balance, or the resulting water resources and general environmental impacts has not been reached for the HKH mountains. It is believed that only a combined effort of local observation, remote sensing and simulation modeling can lead to a better understanding of what’s happening. Especially the modeling is essential to provide projections for the future.

FutureWater has conducted a review of current state of knowledge in (i) climate change datasets and downscaling used for glacier and high mountain modelling, (ii) glacier and snow contribution to river runoff in the HKH region, (iii) hydrological modelling studies used for glacier and high mountain environments and, (iv) downstream impacts of climate change on the HKH region.

The concept of using simulation models in scenario analysis.
Importance of Himalayan’s rivers for people.

The Indus basin is a densely populated area and water supplied by the Indus River is extremely important for agriculture, domestic use and hydropower production. The Indus is largely dependent on melt water generated in the Himalayas, Karakoram and Hindu Kush mountains. Understanding of the hydrological regimes in the mountainous Upper Indus basin (UIB) is essential for water resources management in the region.

It is highly likely that future climate change will impact future water availability in the Upper Indus river basin. Temperature increases and changes in the timing, magnitude, and phase of precipitation will alter the timing and contribution of snow and ice melt.

High-resolution gridded meteorological datasets, which capture the spatial variability of precipitation, are critical for modelling the hydrology of high-mountain regions. In the Upper Indus Basin (UIB), previous modelling studies have demonstrated that snow and glacier melt are major contributors to stream discharge, and on daily or seasonal scales can play even larger roles. However, hydrologic models suffer from a lack of gridded input climate data which accurately reflects the topographic complexity and spatial variability in precipitation. Improvements to existing gridded datasets using high-elevation station data will increase the reliability of hydrological models in the region. FutureWater’s Spatial Processes in Hydrology (SPHY) model will be updated and recalibrated to improve understanding of the stream flow composition in the basin and to provide better estimates of the future water availability, by forcing the model with downscaled CMIP5 general circulation models.

Summarizing, the three main goals of the project are:

  • To develop a high-quality meteorological forcing dataset (temperature and precipitation) for the UIB by merging existing gridded datasets and high-altitude climate observations.
  • To improve the existing large-scale SPHY model by including a reservoir scheme and recalibrating the model with additional observations (geodetic mass balance, time series of river runoff, time series of reservoir inflow data).
  • To use the recalibrated SPHY model to examine shifts in the basin hydrology under CMIP5 climate change scenarios.

The energy sector is sensitive to changes in seasonal weather patterns and extremes that can affect the supply of energy, harm transmission capacity, disrupt oil and gas production, and impact the integrity of transmission pipelines and power distribution. Most infrastructure has been built to design codes based on historic climate data and will require rehabilitation, upgrade or replacement in the coming years. This poses both a challenge and an opportunity for adaptation. Central Asia is one of the most vulnerable regions in the world. Expected climate impacts range from increased temperature (across the region), changes in precipitation and snow, greater extreme weather events, aridisation and desertification, health, and changes in water resources.

Toktogul reservoir, Kyrgyzstan

Energy and water are closely interrelated as water is used to generate energy (hydropower, cooling of thermal plants) but energy is also required to fulfil water needs (e.g. pumping, water treatment, desalination). Especially in Central Asia, meeting daily energy needs depends to a large extent on water. Guaranteeing sufficient water resources for energy production, and appropriately allocating the limited supply, is becoming increasingly difficult. As the region’s population keeps on growing, competing demand for water from other sectors is expected to grow, potentially exacerbating the issue.

The World Bank is committed to working with the governments of Central Asia to undertake analysis and to identify priorities in adaptation to climate change, including strengthening regional trade through a rigorous, transparent region-scale study. Therefore it currently undertakes a regional assessment to identify areas of possible coordination and possible transboundary impact. The overall project objective is to contribute to a better understanding of the challenges and opportunities for effective joint management of climate adaptation, contributing to the objective of the World Bank’s Central Asia strategy of energy and water security through enhanced cooperation. The results of this assessment should guide current and future decision-makers on options for investments in and management of power generation and transmission/distribution assets through enhanced cooperation.

Amy_Darya_Syr_Darya_mapThe objective of this study is to support the “Central Asia Regional Energy Sector Vulnerability Study” led by Industrial Economics (IEc) and funded by the World Bank, by carrying out an expanded risk assessment for water availability and water related energy sector impacts in the region. The work will build on the existing tools developed previously for Syr Darya and Amu Darya basins. Various necessary extensions and enhancements of the tools will be made to include the latest understanding of climatological and hydrological processes and include the latest planned investments in hydropower facilities and cooling water abstractions of the thermal power plants in the region.