The Andean Glacier and Water Atlas

The Atlas focuses on the status of water resources in the Andes, identifying existing vulnerabilities of mountain communities dependent on these resources and proposing possible adaptation strategies and policies to address water vulnerability and security.


UNESCO Publishing

United Nations Educational, Scientific and Cultural Organization

A Centre collaborating with UN Environment

From the shade of an adobe house overlooking Peru’s Santa River, Jimmy Melgarejo squints at the dual peaks of Mount Huascarán looming against a cloudless sky. “The snow keeps getting farther away,” says Melgarejo, a farmer worried about his livelihood. “It’s moving up, little by little. When the snow disappears, there will be no water.”

(from Fraser 2012)

Editors Tina Schoolmeester, GRID-Arendal, Norway Koen Verbist, UNESCO-IHP, France

Published by the United Nations Educational, Scientific and Cultural Organization (UNESCO), 7, place de Fontenoy, 75352 Paris 07 SP, France, and GRID-Arendal, P.O. Box 183, N-4802 Arendal, Norway

Authors Kari Synnøve Johansen, GRID-Arendal, Norway Björn Alfthan, GRID-Arendal, Norway Elaine Baker, GRID-Arendal at the University of Sydney, Australia

© UNESCO and GRID-Arendal, 2018 UNESCO ISBN 978-92-3-100286-1 GRID-Arendal ISBN 978-82-7701-177-6

Malena Hesping, GRID-Arendal, Norway Tina Schoolmeester, GRID-Arendal, Norway Koen Verbist, UNESCO-IHP, France

Contributing Authors Wouter Buytaert, Imperial College of London, United Kingdom Gino Casassa, Geoestudios and Universidad de Magallanes, Chile Raquel Guaite Llabata, Peru Rodolfo Iturraspe, Universidad Nacional de Tierra del Fuego, Argentina Anil Mishra, UNESCO-IHP, France Elma Montaña, Inter-American Institute for Global Change Research (IAI), Uruguay Andres Rivera, Centro de Estudios Científicos, Chile Lucas Ruiz, Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, Argentina Wilson Suarez Alayza, SENAMHI, Peru Mathias Vuille, University at Albany, State University of New York, USA

This publication is available in Open Access under the Attribution-ShareAlike 3.0 IGO (CC-BY-SA 3.0 IGO) license ( by-sa/3.0/igo/). By using the content of this publication, the users accept to be bound by the terms of use of the UNESCO Open Access Repository (http:// and the Commonwealth of Learning’s Open Access Repository ( The present license applies exclusively to the text content of the publication. For the use of any material not clearly identified as belonging to UNESCO or GRID Arendal, prior permission shall be requested from: publication. or UNESCO Publishing, 7, place de Fontenoy, 75352 Paris 07 SP France, or GRID-Arendal, P.O. Box 183, N-4802 Arendal, Norway. The designations employed and the presentation of material throughout this publication do not imply the expression of any opinion whatsoever on the part of UNESCO or GRID-Arendal concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Any ideas and opinions expressed in this publication are those of the authors and do not necessarily reflect the views of UNESCO or GRID-Arendal and do not commit these organizations.

Other contributions Marina Antonova, GRID-Arendal, Norway Barbara Avila, UNESCO-IHP, France Louis Dorémus, GRID-Arendal, Norway Hanna Lønning Gjerdi, GRID-Arendal, Norway Marie-Claire Hugon, UNESCO-IHP, France Laura Puikkonen, GRID-Arendal, Norway Laura Wallace, UNESCO-IHP, France Levi Westerveld, GRID-Arendal, Norway

External Reviewers Mathias Vuille, University at Albany, State University of New York, USA Bolivar Caceres, Instituto Nacional Meteorologia e Hidrología, Ecuador

United Nations Educational, Scientific and Cultural Organization

International Hydrological Programme

Layout GRID-Arendal

The Andean Glacier and Water Atlas is developed in the framework of the project “The Impact of Glacier Retreat in the Andes: International Multidsciplinary Network for Adaptation Strategies”, executed by UNESCO's International Hydrological Programme (IHP) and supported by UNESCO/Flanders Fund-in- Trust for the support of UNESCO's activities in the field of Science (FUST). Recommended citation: Schoolmeester, T., Johansen, K.S., Alfthan, B., Baker, E., Hesping, M. and Verbist, K., 2018. The Andean Glacier and Water Atlas – The Impact of Glacier Retreat on Water Resources . UNESCO and GRID-Arendal.

Copy-editing Strategic Agenda, London

Cartography Riccardo Pravettoni, GEO-GRAPHICS Front cover photo: iStock/naphtalina Back cover photo: iStock/cta88


7 Preface 8 Key messages 10 Policy recommendations 12 Introduction

14 Peaks, plateaus and valleys 25 Living in the Andes 32 A changing climate 41 Shrinking ice 52 Accelerated glacier melt 62 Addressing water challenges

70 Policy recommendations 72 References



Achieving and maintaining water security in vulnerable areas, such as mountainous and arid regions, is challenging. Yet, projections of increased climate variability indicate the situation is only likely to become more complex. To tackle this situation, it is essential to develop mitigation and adaptation policies based on the scientific understanding of climate impacts on water security. In the Andean region, water scarcity and uncertainty are the main issues; many Andean valleys are seasonally dry and depend on glacier runoff to support the people, energy, food production and ecosystems. The Andean Glacier and Water Atlas has been compiled as part of a multidisciplinary project initiated by UNESCO and aided by the Flanders Fund in Trust (FUST). The project, “The Impact of Glacier Retreat in the Andes: International Multidisciplinary Network for Adaptation Strategies”, aims to improve understanding of vulnerabilities, opportunities and potential for adaptation to change, particularly climate change. The Atlas illustrates the significant reduction in glacier mass happening throughout the region. It quantifies the contribution of glaciers to drinking water supplies in cities, agriculture, hydropower and industries, such as mining. The findings highlight the impact of shrinking glaciers on water availability and security for millions of people. The current reliance on glacier melt coupled with the measurable changes being observed mean a strengthened science-policy dialogue is needed. This kind of discussion would raise awareness regarding the impact of retreating glaciers on water resources.

Several Andean countries have initiated processes to protect and conserve glaciers and their strategic mountain water reserves. These initiatives provide concrete examples of how to tackle the challenges considering the local context. The Atlas provides specific recommendations on addressing the issues of water vulnerability and security. This includes improving the understanding of climate change impacts on communities, in order to strengthen local capacities to develop specific adaptation responses. Continued urbanisation in conjunction with reduced glacier runoff will pose additional challenges to mountain cities that are currently dependent on glaciers for their water supply. Improved water governance will be key to ensuring that competing water uses are adequatelymanagedunder the additional pressure. The International Hydrological Programme of UNESCO will continue its support to the Andean countries, as part of its Eight Phase (2014–2021) “Water Security – Responses to Local, Regional, and Global Challenges”, and continue to strengthen the UNESCO working group on snow and ice in Latin America. The atlas also directly supports the implementation of the Sustainable Development Goals (SDGs), the Paris Agreement and the Sendai Framework for Disaster Risk Reduction. We would like to thank the Government of Flanders and the Royal Norwegian Ministry of Climate and Environment for providing financial support for the publication, and all the stakeholders involved, including scientists, governmental agencies, politicians, participating countries and the broader IHP Water Family.

Blanca Jiménez-Cisneros Director, Water Sciences Division Secretary International Hydrological Programme (IHP) UNESCO

Peter Harris Managing Director GRID-Arendal


Key messages

Temperatures have been rising across the Andes. There is evidence of altitude amplification, with temperatures rising faster at higher altitudes. The annual mean temperature in most countries of the Tropical Andes (Venezuela, Colombia, Ecuador, and Peru) increased by approximately 0.8°C during the 20th century. The altitude of the freezing level height has also risen by an approximate average of 45 m across the region. In the Andean mountains of Chile and Argentina, temperatures have risen between 0.2 and 0.3 per decade since the mid-1970s. Temperatures could increase further in the Tropical Andes by between 2°C and 5°C by the end of the 21st century, according to certain projections. In the Southern Andes temperatures could increase by between 1°C and 7°C. The degree of warming is also likely to be greater at higher elevations. Much larger inter-annual temperature variability and a higher likelihood of extremely hot years can also be expected. Even the coldest years could become much warmer than the warmest years observed today. Past precipitation trends are less clear, but there are indications snow cover has been decreasing over the past few decades. Precipitation trends are difficult to identify in the Andes due to the lack of reliable long-term observational records. Annual precipitation is already highly variable because it depends on location and is influenced by El Niño events. However, snow cover has seen an overall decreasing trend in the past two decades, in line with rising temperatures. This has been especially significant in the Central Andes and on the eastern flanks. In the Southern Andes, the snow line is also moving upwards which is increasing the risk of flash floods downstream.

Future precipitation trends are difficult to estimate, with projections revealing a mixed picture across the Andes region.

Most models predict an increase in precipitation during the wet season and a decrease during the dry season in the tropical Andes, as well as over the Altiplano region. Under the IPCC high emission scenario, by 2100, precipitation is projected to increase along the coastal regions of Colombia and Ecuador and in some places along the eastern Andes, and south of the equator. However, by 2100, precipitation is projected to decrease in the southern (tropical) Andes, including the Altiplano regions; which would lead to increased drought. Important reductions in precipitation of more than 30 per cent are expected in the southern Andes, particularly in Chile and Argentina. Most glaciers have been retreating around the world since the beginning of the 18th century. This retreat is linked to anthropogenic climate change. The pace of retreat and loss of certain glaciers is most rapid within the Tropical Andes. In Venezuela, just one glacier remains, and it is predicted to disappear by 2021. In Colombia, rapid retreat has occurred and has accelerated over the past few decades. By the middle of this century it is likely that only the largest glaciers on the highest peaks will remain. Ecuador’s glaciers are restricted to the country’s highest peaks and within two mountain ranges, but its glacial loss has been dramatic over the past 50 to 60 years. Peru hosts the largest number of tropical glaciers on the continent. Of two major glacial systems in the country, the Cordillera Blanca glaciers have been retreating rapidly over the past few decades, although there have been some brief periods of advancement. Rapid glacial retreat has also been observed on Bolivia’s glaciers since the 1980s, with some glaciers having lost two-thirds or more of their mass. Many of the glaciers, with an area of less than 0.5 km 2 , are so small that they are even more vulnerable to glacial retreat. In Chile and Argentina, most glaciers are retreating, and the rate has increased over the last decades. Large, low-lying, tidewater and freshwater glaciers in Patagonia and Tierra del Fuego have experienced rapid retreat. Although less rapid, retreat is also occurring in glaciers at higher altitudes. A few glaciers are still advancing due to local ice dynamics. Glaciers are retreating in every Andean country. The most rapid retreat is in the Tropical Andes, in lower-altitude glaciers.


During drought years, glacial meltwater becomes critically important for certain areas.

Glacial meltwater can be extremely important, especially within the Tropical Andean region, which is highly populated and includes some major population centres. During a normal year, glacier meltwater contributes to around 5 per cent of the available water supply in Quito, Ecuador, 61 per cent in La Paz, Bolivia, and 67 per cent in Huaraz, Peru. During a drought year, the maximum monthly contribution of water from glaciers increases to around 15 per cent in Quito, 85 per cent in La Paz and 91 per cent in Huaraz. ‘Peak water’ has been reached for many glaciers in the Andes, meaning that meltwater runoff will continue to decrease in the future. As glaciers melt, they provide meltwater. Peak water refers to a point in time where meltwater runoff is at its maximum. For many glaciers in the Tropical Andes, ‘peak water’ was reached in the 1980s and these glaciers have been contributing less and less meltwater over time. For many glaciers, peak water has either already recently been reached or it will be within the coming 20 years. Future glacier shrinkage will lead to a long-term reduction in dry season river discharge from glacierised catchments. The highest impacts will be felt in areas where meltwater significantly contributes to the available water supply, especially during the dry season. Consequently, these are the areas with the greatest needs to adapt to a reduced availability of glacial meltwater.

Glacier retreat and volume loss is ‘locked in’ and will continue in the future across the whole of the Andes, leading to significant changes in hydrology. This will impact communities and ecosystems. The extent of loss depends on which IPCC warming scenarios are used for projections. Even under the least warming scenario, glaciers will continue to shrink. The most dramatic retreat and volume loss is expected for tropical glaciers, where even under moderate warming scenarios, volume losses of between 78 and 97 per cent are projected by the end of the century. In the Southern Andes glaciers are expected to further decrease and the rate of loss is expected to accelerate.

Climate change adaptation is essential for healthy societies and ecosystems.

The Andean region is undergoing significant climatic changes that will have far-reaching consequences for the environment, and the lives of many Andean people. Communities will need to tackle the challenges resulting from climate change, such as water scarcity, unpredictable water availability, and flooding and other climate hazards. Adaptation needs to be based on careful analysis of the underlying socio-economic factors of vulnerability to climate change in order to avoid maladaptation.

Glacial meltwater is a critical water source at certain times of the year for millions of people – most notably for those living in the Andean highlands of Bolivia, Chile and Peru.

However, its importance is seasonal and not uniform across the Andes, with people in certain regions being more reliant on it than others. The Andean highlands of Bolivia, northern Chile and southern Peru are hotspots of water stress, because of their semi- arid climate and marked seasonality. With limited hydrological storage capacity in the small upland catchment flows, glacier meltwater has so far acted as an important buffer mechanism.


Policy recommendations

Increase support for science-based policy decisions

Implement preventive measures for natural hazards related to glaciers

The interaction between science and policy is often weak and hampered by the definition of common goals and objectives. Joint problem framing and more effective interaction between social and physical climate and impact sciences is needed. Grounding policy in science will help to effectively allocate resources to address the environmental challenges caused by climate change in the Andes and the associated threat to lives and livelihood. There is a particular need to consider local and indigenous knowledge systems as a valuable source of information for sustainable management of fragile mountain ecosystems. By ensuring that traditional knowledge and sciences co-produce information for policymaking, enables these livelihoods to address the challenges posed by climate change impacts. Bottom-up and top-down approaches have the opportunity to meet and create a stronger outcome (Huggel et al. 2015). Many aspects of future climate change remain highly uncertain, due to old and inadequate climatic and glaciological monitoring networks. Improved data-gathering infrastructure is needed to monitor climate change at the elevation of the glacier, including a network of automated weather stations at high elevations and improved on-site monitoring. Equally, better inclusion of these data with advanced remote sensing and geographic information system applications is urgently required. On the modelling front, more detailed climate change projections, relying on a variety of models and several different emissions scenarios are needed, particularly considering that climate change impacts are disproportionately high in mountains. Map the current and projected impacts of climate change on Andean glaciers

For risks from Glacial Lake Outburst Floods (GLOFs), adaptation measures should focus on implementation of preventive measures, including for example creating hazard maps, regulating building codes and land use planning, and creating early warning systems, complemented by comprehensive education and awareness programmes (Vuille et al. 2018).

Develop climate services

There is a need for targeted climate services for water resources management, to ensure that monitoring and early warning information reaches the water users in an appropriate format and timing. This requires a better understanding of the real needs of local stakeholders, based upon a bottom-up assessment of water security vulnerabilities, in order to tailor specific climate services to inform current and future hazards. The penetration of cell phones and smart phones in even the most remote locations provides a novel pathway for dissemination to and interaction with local water users. Recognising that water usage is impacted by societal forces and trends, further in-depth research and understanding is needed of water demand and use trends. Population dynamics, urbanisation, changing consumer patterns, demands for certain goods within international markets and the development trajectories of different sectors, including agriculture, mining and hydropower all influence water usage. Furthermore, water auditing and efficiency tools should be applied to each sector to determine where water conservation measures can be made. With the irreversible loss of many glaciers that will occur in the Andes, irrespective of any current or future mitigation, scenario development/planning should be undertaken for water resource management in order to anticipate and deal with future uncertainty and scarcity. Increase understanding of water demand and use – now and in the future

Implement good water governance

The importance of water governance should be recognized at the highest level of decision-making. Integrated water resource management (IWRM) approaches should continue to be developed across the Andes countries, while integrating new information about projected climate impacts and trends.


Promote mechanisms for adaptation learning

Long-term monitoring and evaluation of adaptation projects and initiatives should be undertaken in order to measure adaptation actions according to a pre-defined set of criteria, which could include effectiveness, efficiency, equity, inherent flexibility, acceptability and robustness. Platforms and mechanisms should be developed which allow for experiences and lessons to be shared between and within countries and across a wide diversity of stakeholders (including municipalities, rural communities, civil society, private sector, national governments etc.). The Climate Risk Informed Decision Analysis (CRIDA) provides such a framework to develop adaptation pathways under climate change uncertainty (UNESCO and ICIWaRM, 2018). The most effective mechanism for responding to changes in water availability is improving adaptive capacity, including training of farmers and other stakeholders and developing and implementing or accessing technology and building supporting infrastructure. These actions require viable financing options. In order to offset the decreasing amount of water, which was previously stored in snow and ice, investment is needed in water storage and distribution systems as well as in natural water retention methods. For example, multiple use water storage systems should be encouraged, which can supply multiple water needs such as drinking water and irrigation. Innovative financing mechanisms, such as municipal water funds, should also be explored. Furthermore, focussing on increasing and/or diversifying the range of livelihood options, that are available to local communities can also help spread risk and allow for different adaptation strategies to be adopted. Accessing new technologies, including decentralised small-scale hydropower systems, should also be explored where relevant. Finance adaptation measures

strategies. The IPCC has started to focus on the climate risks in mountains with a special report soon to be published. This should lead to mountains being included in the next IPCC global assessment report.

Make mountains a focus of targeted adaptation policy

Increase policy coordination and integration within and between countries

A growing number of organisations in Latin America are working on climate change adaptation specific to mountain areas (ELLA, 2017). However national adaptation policies rarely recognise the unique problems and challenges encountered in high mountains (Schoolmeester et al., 2016). The World Bank Mountain Vulnerability Framework (Brodnig and Prasad, 2010) recognises mountain specificities, such as accessibility, fragility and marginality that can be assessed to develop tailored adaptation

Countries could benefit from harmonising policies and aligning national laws to protect mountain environments, building further on the lessons learnt in some of the Andean countries that have adopted novel approaches. The UNFCCC recognises the potential gains from regional synergies that promote joint efforts in the development and implementation of adaptation actions. These include knowledge sharing, avoiding duplication, economies of scale and cost sharing and conflict minimisation.



Mountains are often referred to as the water towers of the world, given their role in providing water to populations around the globe. This could not be truer than in the Andean region, where mountains play a crucial part in providing water to over 75 million people within the region, and a further 20 million people downstream. Some of this water is provided through rainfall. At higher elevations the glaciers have long provided a steady stream of meltwater when it is most needed, during the dry season. Yet the Andes is not, and has not been, immune to climate change. Several archaeologic studies have linked climate stress to the cultural behaviour of civilisations in the Andes (Binford et al., 1997; Dillehay & Kolata, 2004; Tung et al., 2016). The collapse of the Tiwanaka civilisation for example, coincided with rapid and significant climate change; drier conditions had affected the hydrological and ecological characteristics of the land the people used for agriculture (Binford et al., 1997). This mountainous region is once again entering a period of unprecedented change. Glaciers in the Andes are some of the fastest retreating in the world. In some areas, many glaciers have disappeared, while in other areas a steady decline will continue for decades to come.

With fast retreating glaciers, there is a paradox. Over the past few decades, many communities living beneath them may have enjoyed a period of relatively more abundant water, as the glaciers have released their meltwater. The evidence now shows most glaciers have reached their peak water output or will reach it within the coming decades. The signals are clear. They point to an urgency to better understand the environmental changes to come and to implement suitable adaptation responses. This atlas has been designed to provide a comprehensive overview of the status of glaciers across the Andes region and possible adaptation options. It is intended for policy makers in the region, as well as the general public. The start of the atlas focuses on introducing the region both in geographical, historical and socio-economic terms. Then, it describes the climate and specifically examines past and projected trends in temperature, and precipitation. The section entitled “Shrinking Ice” provides more detailed insights into glacial trends in each Andean country and projected trends. The “Accelerated Glacier Melt” section examines the impact on communities and various sectors of glacial melt and glacial outburst floods. A non-exhaustive overview of adaptation options is then provided and includes a series of best practise cases. The atlas concludes with a series of recommendations, particularly targeted at policy makers.




The Andes are the longest continental mountain range in the world, extending for more than 7,000 km from Venezuela in the north to Argentina in the south. Geographically they can be divided into three regions; the Northern Andes which includes the Venezuelan, Colombian and Ecuadorian mountains, the Central Andes which encompasses the Peruvian and Bolivian mountains and the Southern Andes which consists of the Chilean and Argentinean mountains. Together the Northern and Central Andes form the Tropical Andes. The Southern Andes is often referred to as the extratropical Andes. Peaks, plateaus and valleys

that started approximately 140 million years ago (Isacks, 1988). This collision caused the formation of a series of parallel mountain chains or cordilleras, interspersed with high peaks, plateaus and valleys. The Andes are the second highest mountain range after the Himalayas and are a defining feature of the South American continent. They have an average altitude of 4,000 m, with many peaks higher than 6,000 m above sea level (Arana, 2016). The highest mountain, Mount Aconcagua in Argentina is 6,908 m. The ongoing tectonic movement in the Andes generates frequent earthquakes and volcanic activity. Extinct or active volcanos can be found across the region, including the highest volcano on earth, Ojos del Salado in Chile, which is 6,893 m (Borsdorf & Stadel, 2015). The Dry Andes stretch over most of western Argentina and central Chile and are divided into two sub-zones: the Desert Andes, which extend from the northern boundary of Chile to the Choapa Basin (~17°30 ' –32° S) and the smaller Central Andes (32–36° S) (Lliboutry 1998; Barcaza et al., 2017). Due to low precipitation, glaciers do not occur in the Desert Andes, only permanent snow patches and glacierets (Lliboutry 1998). In contrast many large glaciers are found in the wetter central Andes, which are characterised by a Mediterranean climate with wet winters (April–September) and dry summers (October–March) (Barcaza et al., 2017). The Wet Andes is the southern sub-region of the Argentine and Chilean Andes. It extends south of the Itata river, where the elevation of the mountains decreases sharply, to Cape Horn. The area includes the heavily glacierized Patagonian Andes and the sub-polar Tierra del Fuego archipelago and is characterised by increased annual rainfall with a strong west– east gradient (Garreaud, 2009; Barcaza et al., 2017).

The Andes were formed as a result of the subduction of oceanic plates under the South American continental plate; a process

A diversity of climates

Crossing seven countries, Venezuela, Colombia, Ecuador, Peru, Bolivia, Argentina and Chile, the Andes covers three large climatic zones. These are generally defined as the Tropical Andes, the Wet Andes and the Dry Andes. Within these broad zones, however, there is considerable climatic variation – also from east to west – reflected in numerous complex sub-zones that occur as a result of orography, regional and local atmospheric circulation patterns and ocean currents. The Tropical Andes extend from their northernmost point (which includes high islands in the Caribbean), southwards until the Bolivian border (Cuesta et al., 2012). The northern part of the Tropical Andes is very wet with low seasonal temperature variability. The high rainfall sustains dense cloud forests. The southern Tropical Andes are drier, with the highest rainfall occurring during the summer months and a distinct dry season from April to September (Espinoza et al., 2015).



Andes glaciers Glaciers are thick masses of ice which flow slowly due to gravity. Glaciers, including the ice sheets of Greenland and Antarctica, cover about 10 per cent of the world’s land surface and store about 75 per cent of global freshwater (National Snow and Ice Data Center, 2018). In the Andes, the greatest number of glaciers is found along the border between Chile and Argentina (approximately 4,000). A smaller number are found in the Tropical Andes, which constitute more than 95 per cent of the world’s tropical glaciers (Vuille et al., 2008). The largest number of tropical glaciers is located in the Peruvian Andes, with the Quelccaya Ice Cap located in the Cordillera Vilcanota being the largest single ice body in Peru (Hastenrath, 1998). In the Andes, glaciers only form above the snowline, where snow persists throughout the year. Their formation depends on latitude, altitude, and annual precipitation. As snow accumulates it compresses the underlying snow, creating a layer of dense snow, called a firn. As the snow continues to accumulate the pressure increases, further compacting the firn, which develops into solid

This complex topography, coupled with elevation, altitude and climatic gradients has made the Andes one of the most ecologically diverse mountain systems in the world (Borsdorf & Stadel, 2015). The wide variety of ecosystems with their rich flora and fauna, have long provided support for human settlements. Features include high-land plateaus, sometimes referred to as mountain knots, that are formed where mountain chains meet. Some of the highest cities in the world, such as La Paz in Bolivia and Quito in Ecuador are found on these high plateaus. The Andes cryosphere The cryosphere, originating from the Greek word for cold, kryos, consists of areas where water is frozen. It includes places that are either seasonally or year-around below freezing. The cryosphere on land includes areas of snow cover, glaciers, ice caps, ice sheets, river and lake ice, permafrost and seasonally frozen ground. The cryosphere plays an important role in climate with many direct links and feedbacks. These influence surface fluxes of energy and moisture, cloud formation, precipitation and atmospheric and oceanic circulation (Khromova, 2010). In the Andes, the freezing and melting regime of snow and ice has a significant impact on alpine hydrology and ecology (Diaz et al., 2003).


Tropic of Cancer


Glaciers in the Andes

Pico Cristbol Coln





Pico Bolvar



Ritacuba Blanco




Nevado del Ruiz 5.311





Volcan Galeras

Glacier monitored by the World Glacier Monitoring Service Glacier


Equator line





Glacier length Kilometres










Glacier area Square kilometres




1.265 (Pio XI Brueggen, Chili)

Nevado Auzangate



Nevado Coropuna




Nevado Illimani



Nevado Sajama

100 10 1








Tropic of Capricorn


Volcan Llullaillaco



Nevado Ojos del Salado



Cerro Aconcagua



6.550 Cerro Tupungato



Buenos Aires

Volcan Domuyo





Monte Tronador



Cerro San Valentn



Monte Fitz Roy




Source:World Glacier Monitoring Service database, accessed February 2018.


During periods of increased snow mass accumulation or ablation, the equilibrium is disrupted and the glacier will either advance or retreat more than normal (National Snow and Ice Data Center, 2018). Few glaciers ever remain at equilibrium. While glaciers are extremely sensitive to environmental and climatic changes, they also play a role in influencing the global climate. For example, the reflective capacity of ice and snow is important in regulating atmospheric temperature. The term ‘albedo’ describes the ability of surfaces to reflect solar radiation. Dark surfaces have a low albedo, which means they absorb more energy and warm up, while white surfaces have a high albedo, reflecting a large part of solar energy back into space. The high albedo of ice and snow keeps these surfaces cooler. The more atmospheric temperatures rise, glaciers shrink, and snow cover disappears, the more radiation is absorbed by the surrounding darker ground, which warms and reinforces the melting. This is an example of a positive feedback loop. Shrinking glaciers and reduced snow cover are not the only concern in regard to the earth’s changing albedo. Black carbon is emitted into the air as fine particles as a result of incomplete combustion, for example from wood fired stoves or from diesel burning engines. When the particles sink to the ground, they create a layer of soot. These fine particles can travel relative far in the air and, when covering glaciers or snow, they darken the surface and reduce the glaciers’ albedo. This causes the glaciers to absorb more sunlight and warm accordingly. Research shows that glaciers near population centres, where polluting activities are concentrated, are more affected by black carbon pollution than those further away (Schmitt et al., 2014).

glacier ice. When this ice gets thick enough the glacier begins to flow, due to the force of its own mass under gravity, either by sliding or internal deformation. A glacier can be divided into two zones; the upper accumulation zone, where the snow mass accumulates and the lower ablation zone, where more glacier mass is lost, or ablated, than gained through snowfall. Ablation can occur due to melting, wind erosion and calving (National Snow and Ice Data Center, 2018). The point between the two zones where accumulation equals ablation is termed the equilibrium line. The equilibrium line is visible on temperate glaciers, a glacier at melting point that contains liquid ice. The line marking the boundary between new snow and old snow (firn) exposed by melting. However, the line tends to be diffuse on polythermal glaciers, which have a complicated thermal structure (Hambrey & Alean, 2016).

Glacier mass balance

Snow precipitation


Lateral moraine

Accumulation zone

Snow and rn

Pressure and solution

Equilibrium line

Snow akes

Terminal moraine



Glacial Lake

Granular snow (50% air)

Ablation zone

Flood plain


Melting front

Glacier movement

Firn (25% air)


GEO-GRAPHICS / GRID-Arendal 2018


Glacier distribution, surface area and altitude in the Andes


10º N

Equator line

10º S

20º S


Tropic of Capricorn


30º S

Glacier area

40º S

Square kilometres






50º S

10 5 or less


1 000

2 000

3 000

4 000

5 000

6 000

6 640

Altitude Metres

GEO-GRAPHICS / GRID-Arendal 2018

Sources: World Glacier Monitoring Service database, accessed February 2018.

Glacier classification

based on World Glacier Monitoring Service (WGMS) and Global Land Ice Measurements from Space Initiative (GLIMS) Morphology – Primary Classification

Mountain glacier Develop in high mountain regions and can range from small masses of glacial ice to large valley-filling systems. Mountain glaciers include cirque, niche or crater type, hanging glaciers and ice aprons. Ninety-one per cent of the glaciers of Peru’s Cordillera Blanca are mountain glaciers.

Outlet glacier Flows down from an ice sheet, ice field or ice cap beyond its margins. Has no clearly defined catchment area and usually follows local topographic depressions.

Valley glacier

A glacier that flows down a valley and has a well-defined catchment area. Ice free slopes usually overlook the glacier surface.

Ice field Approximately horizontal ice-covered area (no dome shape) smaller than 50,000 km 2 . Ice masses are not thick enough to obscure the subsurface topography. Two of the world’s most extensive ice fields are found in Patagonia.

Glacieret A small ice mass of indefinite shape that forms in hollows, river beds and on protected slopes. Glacierets develop from snow drifts, avalanches and heavy snow accumulation in certain years. Usually there is no visible flow pattern with almost no ice movement. The accumulation and ablation areas are often not clearly defined.

Ice cap Dome-shaped masses of glacier ice with radial flow. An example is the Quelccaya Ice Cap located in Peru. The ice cap is at an average altitude of 5,470 m and spans an area of 44 km 2 (Thompson et al., 1985).

Rock glacier

A glacier-shaped mass of rock in a cirque or valley containing interstitial ice, slowly moving downslope as a debris mass.


Glacier classification

(WGMS and GLIMS) Selected glacier types found in the Andes, based on secondary characteristics

Tidewater glacier Glaciers that flow down into the ocean. They often calve numerous small icebergs. Numerous tidewater glaciers in Patagonia originate in the ice fields and terminate in the Chilean fjords.

Cirque glacier A special type of mountain glacier that forms in a cirque – an amphitheatre-shaped depression on the side of a mountain in which snow and ice accumulates. As cirque glaciers grow, they may spread into valleys and form valley glaciers. Venezuela has one remaining cirque glacier, the Humboldt glacier.

Piedmont glacier

A type of ice field formed on a lowland by the lateral expansion of a glacier or the coalescence of several glaciers.

Hanging glacier

A glacier perched on a steep mountain-side or issuing from a hanging valley.

Debris covered glacier A mountain glacier where the ablation area is covered by rock debris. The debris is predominantly derived from rockfall but may also contain basal debris that has reached the surface due to deformation processes. In the accumulation area rock debris is mixed with snow. When it moves into the ablation area, melting increases the concentration of debris at the surface.

Ice apron

Steep, ice covered mountain faces. Usually thin ice mass which adhere to a mountain slope or ridge.

Sources: Cogley et al., 2011; Rau et al. 2005; National Snow and Ice Data Center, 2018; Hambrey & Alean 2016; and Braun & Bezada, 2013



Rivers, basins and lakes Most of the large rivers in South America are fed by water from the Andean mountain range. These high mountains often receive more precipitation than lowlands. In general, they also have glaciers and snow-covered areas, which provide a large reservoir of water. This storage capacity and the release of meltwater are especially important in regions with a high degree of seasonality and low levels of precipitation.

The Amazon river basin is the largest drainage basin in the world, covering an area of almost 6 million km 2 . It occupies more than one third of the South American land mass and contributes almost 20 per cent of the freshwater discharge to the ocean (Calléde et al., 2010; FAO 2015). The transboundary basin has five main tributaries: the Negro river, which drains the Brazilian Shield in the northern Amazon; the Solimões river, which drains the Northern and Central Andes and a large part of the Lowlands; the Madeira river, which drains the Southern Andes, the Southern Foreland basins and part of the Brazilian shield; the Tapajós and Xingu rivers, which drain the remaining area of the Brazilian shield (Bouchez et al., 2017). Glaciers in the eastern cordilleras of Bolivia and Peru contribute to the hydrological cycle of the Amazon Basin. However, their influence tends to decrease rapidly downstream due to the high contribution of precipitation along the eastern slopes of the Andes (Bookhagen and Strecker, 2008). It is estimated that the Amazon rainforest generates and recycles as much as 50 per cent of this precipitation (Jones et al., 2017). On the eastern side of the range and south of the Amazon basin, the La Plata basin covers an area of around 3.1 million km 2 . This transboundary basin includes parts of Brazil, Argentina, Paraguay, Bolivia and Uruguay. It is composed of three large sub-basins, principally fed by the Paraná, Paraguay and Uruguay rivers. The Paraná and Uruguay rivers join the La Plata River which discharges into the Atlantic Ocean near Buenos Aires. In addition to rivers, lakes play a vital role in the hydrology of the Andes and provide water and hydroelectric power for many communities. Many of the high-altitude lakes were formed by glacial movement and are fed by cold turbid meltwater from glacial ablation (Barta et al., 2017). In the Northern Andes wetlands, called páramos and cloud forests are important for water storage (Buytaert et al., 2017). Water yield in these generally wet regions is high, as the wetland soils are usually saturated and therefore have high runoff (Mosquera, Lazo, Célleri, Wilcox, & Crespo, 2015).



Living in the Andes

Humans have survived and flourished in the Andes for thousands of years. The oldest, high-altitude settlement in the world, discovered at 4,500 m above sea level in the Peruvian Andes, is thought to date to more than 12,000 years old. This suggests that hunter-gatherers occupied high altitude environments of the Andes just 2,000 years after their initial entry into South America (Rademaker et al., 2014). The process of the domestication of crops and livestock in the region is thought to have started between 8,000–9,000 years ago, with vital crops like potato, squash, cotton, and perhaps maize being grown at this time (Dillehay et al., 2007; Piperno & Dillehay, 2008). This coincided with rapid population growth in the South-Central Andes at this same time (Perez et al., 2017). By the early 16th century, the central Andes were the centre of the Inca Empire, the largest empire the New World had ever seen. About 15 million people were thought to inhabit the Andes mountains (Denevan, 1992). Much of the expansion of the Inca Empire into modern/day Colombia, Ecuador, Chile and Bolivia

from AD1100 until the arrival of the Spanish in AD1532 is thought to be due to increased crop productivity, linked to favourable climate conditions and a 400-year warming period. This allowed the Inca and their predecessors to exploit higher altitudes and build agricultural terraces that used glacial meltwater-fed irrigation (Chepstow-Lusty et al., 2009). The Andes continue to be a major influence on seven of South America’s fourteen countries in modern times, having left their indelible mark on the culture and language in the region. According to figures from 2012, about 44 per cent (75 million people in 2012) of the total population of the seven countries live within the Andes mountainous region (Devenish & Gianella, 2012). Spanish is spoken across all countries, and a large number of other indigenous languages are spoken across the region. For example, variations of the Quechua language, which have survived since Incan times, are spoken by about 10 million people. Indigenous languages are official languages in Peru and Bolivia, within regions of Colombia and Ecuador, and are recognised in political constitutions within Venezuela and Ecuador.


Population in the Andean region Population in the Andean region Population in the Andean region Million people


Million people



Million people



Colombia Argentina






Venezuela Peru Venezuela Peru Venezuela Peru







Chile Ecuador


Ecuador Chile









1960 1970 1980 1990 2000 2010 2015


1960 1970 1980 1990 2000 2010 2015


1960 1970 1980 1990 2000 2010 2015 Source: TheWorld Bank, 2018


Source: TheWorld Bank, 2018



Source: TheWorld Bank, 2018


The Andean countries in numbers





15 692

1 141


5 805






6 018


Thousand square kilometres Country area

1 285



6 049

Andean area



Total area

Country population Million people


1 099


Population living in the andean region

3 105



Total population


Urban extent in the Andes





13 792

Percentage of urban extent located in the Andes


GDP per capita, 2016* Current US Dollars

*Data for Venezuela refer to 2014


2 766

12 440


Source: CONDESAN, Sustainable Mountain Development in the Andes, 2012; The World Bank, 2018

GEO-GRAPHICS / GRID-Arendal 2018

experience social exclusion; for example when various rights, opportunities and resources are less available or systematically blocked to persons or groups. In the Andean countries, indigenous people and rural communities have traditionally lived under lower standard living conditions and with lower levels of education, as well as lack of access to economic markets and political decision- making (Borsdorf & Stadel, 2015). This has also influenced their access to land, water and other resources. The marginalisation of indigenous communities continues to remain a challenge for several of the Andean countries, albeit there has been increasing awareness on the topic. In Bolivia and Peru for example, greater empowerment and autonomy of indigenous communities has been visible (Andolina, Laurie & Radcliffe, 2009; Borsdorf & Stadel, 2015: Martin & Wilmer, 2008). The Andes´ influence extends well beyond its own geographical range and contributes significantly to the GDP of the Andean countries. For example, apart from serving the needs of the millions of people in the region itself, water from the Tropical Andes is of crucial importance for at least a further 20 million people living downstream. Almost all of the major cities on the western Pacific slope of the Andes rely heavily on water and the energy produced from hydropower, which the Andes mountains provide (Devenish & Gianella, 2012). The Andes are vital as a

The social, economic and political reality of the Andean countries varies significantly, while there are also a number of common issues. The countries have experienced economic growth and poverty reduction during the last decades, but there have also been examples of serious setbacks as a result of national or global financial crisis. The economic disparity between the economically stronger and weaker Andean countries has continued to remain, and despite progress, poverty continues to be a core issue. The illicit drugs industry, as well as corruption remains high on the agenda of socio-economic challenges of the countries (Thoumi, 2002). Populations within the seven Andean countries have been steadily urbanising for decades, and the total urban population now ranges from 63.9 per cent in Ecuador to 91.8 per cent in Argentina (United NationsPopulationDivision, 2014). The reasons for theurbanisation are multifaceted, including poverty in the rural areas, temporarily or seasonal livelihood opportunities, and internal displacement as a consequence of insecurity issues (Castles, de Haas & Miller, 2014; Grau & Aide, 2007). Rural populations are also drawn to cities due to improved living conditions, which can include higher income, lower infant mortality and longer life expectancy (Grau & Aide, 2007).

Rural mountain communities (many of which are indigenous people), are often disproportionally poor and are more likely to


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