• Some of the world’s most iconic glaciers are set to disappear by 2050, according to a new study by UNESCO, which highlights the accelerated melting of glaciers in World Heritage Sites. 

• These include Dolomites in Italy, Yellowstone National Park and Yosemite National Park in the United States and Mount Kilimanjaro in Tanzania.

• As many as 50 UNESCO World Heritage sites are home to glaciers, representing almost 10 per cent of the Earth’s total glacierized area. They include the highest (next to Mt. Everest), the longest (in Alaska), and the last remaining glaciers in Africa.

• The UNESCO study, in partnership with the International Union for Conservation of Nature (IUCN), shows that these glaciers have been retreating at an accelerated rate since 2000 due to CO2 emissions, which are warming temperatures.

• Glaciers in a third of sites are under threat, regardless of efforts to limit temperature increases.

• However, the study outlines that it is still possible to save the other two-thirds, if the rise in global temperatures does not exceed 1.5°C compared to the pre-industrial era.

The critical importance of glaciers for sustaining life on Earth

• Covering about 10 per cent of the planet’s surface, ice masses are crucial for sustaining life on Earth.

• Glacial ecosystems provide vital resources to a significant proportion of the global population because of their high biological diversity and ecosystem services such as sediment sinks, freshwater reservoirs and habitats for biodiversity. 

• The benefits include freshwater for domestic use, agriculture, industry and hydropower, as well as climate regulation.

• About 50 per cent of the global biodiversity hotspots on the planet are located in basins drained by glaciers and contain a third of the entire terrestrial species diversity.

• Often referred to as natural “water towers”, glaciers in mountains provide lowlands with essential freshwater supply. 

• The High Mountain ranges of Asia are covered by approximately 100,000 km² of glacier ice and feed the great rivers of Central Asia (Amu Darya and Syr Darya) and South Asia (Brahmaputra, Ganges and Indus), Southeast Asia (Huang He, Mekong and Yangtze). 

• The Antarctic and Greenland ice sheets are the largest bodies of ice in the world and play an important role in the global climate system. They serve as a global thermostat regulating ocean circulation, and their white ice cover cools the atmosphere by reflecting sunlight (albedo effect).

• Glaciers are a sensitive indicator of climate change and one that can be easily observed. Although there are around 200,000 glaciers on the planet, only a few hundred are currently monitored in-situ because they are often difficult to access. Satellite imagery has thus become one of the most valuable methods to keep track of the world’s retreating glaciers.

The dynamics of glaciers

• Glaciers are bodies of moving ice that develop as snow accumulated in cold places compacts and recrystallizes. The formation of a glacier takes decades to millennia, and its size varies depending on the amount of ice it retains throughout its lifespan. 

• Each year, glaciers gain and lose mass. They gain mass from snow and precipitation in their upper portions (accumulation zone) and lose mass in their lower portions (ablation zone) by partially melting in summer. In marine-terminating glaciers, they also lose mass by calving icebergs that float away.

• The balance between accumulation and ablation is the mass balance of the glacier. If accumulation is greater than ablation, then the glacier has a positive mass balance and will advance. If ablation is greater than accumulation, then the glacier has a negative mass balance and will retreat. 

• The glacier terminus is the end of a glacier at any given point in time. Changes in the terminus position are often used as an important indicator for monitoring the long-term dynamic behavior of glaciers. 

• Earth’s glaciers vary incredibly in their sizes and shapes, ranging from small cirque glaciers to ice masses hundreds of meters thick in mountains and ice sheets. 

There are two main groups of glaciers:

i) Unconstrained glaciers have a morphology and flow pattern largely independent of underlying topography, like polar ice caps or the Antarctic and Greenland ice sheets.

ii) Constrained glaciers have a morphology and flow pattern strongly dependent on underlying topography, like ice field, cirque, valley, piedmont and tidewater glaciers.

World Heritage Sites

• Adopted in 1972, the UNESCO Convention Concerning the Protection of the World Cultural and Natural Heritage (World Heritage Convention) has been ratified by 194 States united in a shared objective to protect and cherish the world’s most outstanding natural and cultural heritage. 

• Under this unique international Convention, more than a thousand natural, cultural and mixed (both natural and cultural) sites are currently recognised for their Outstanding Universal Value – “cultural and/or natural significance which is so exceptional as to transcend national boundaries and to be of common importance for present and future generations of all humanity” – and inscribed on the UNESCO World Heritage List.

Disappearing World Heritage glaciers

• Glaciers have been identified in 50 sites on the UNESCO World Heritage List. Around 18,600 glaciers have been identified in 50 World Heritage sites. From very small cirque glaciers (less than 10 km²) to large ice caps (more than 1000 km²), all types of glaciers can be found in World Heritage Sites.

• Projections indicate that, regardless of the applied climate scenario, glaciers in all World Heritage sites outside the polar ice sheets with glacierized areas less than 10 km² may almost completely disappear by 2050.

• These glaciers span an area of about 66,000 km², representing almost 10 per cent of the Earth’s glacierized area. 

• World Heritage glaciers lose on average some 58 billion tonnes of ice every year — equivalent to the total annual volume of water consumed in France and Spain together — and contribute to almost 5 per cent of global observed sea-level rise. 

• Projections indicate that glaciers in one-third of World Heritage glacierized sites will disappear by 2050 regardless of the applied climate scenario and glaciers in around half of all sites could almost entirely disappear by 2100 in a business-as-usual emissions scenario.

The way forward

• The main action to counteract substantial glacier retreat worldwide due to climate change is to drastically cut greenhouse gas emissions to limit global warming to 1.5°C in line with the Paris Agreement agreed under the United Nations Framework Convention on Climate Change (UNFCCC). 

• If emissions are drastically cut to limit global warming to 1.5°C relative to pre-industrial levels, glaciers in two-thirds of World Heritage sites could be saved. 

• At site level, adaptative measures need to be strengthened to respond to inevitable glacier changes in the near future. 

• These include identifying knowledge gaps and improving monitoring networks, designing and implementing early warning and disaster risk reduction measures, making glaciers a focus of targeted policy, and promoting knowledge exchange, stakeholder engagement and communication.

• The successful implementation of these measures requires the mobilisation of key stakeholders (like governments, civil society, Indigenous Peoples, local communities and the private sector) to develop sustainable financing and investments, notably through the establishment of an international fund for glacier research and monitoring.

• Monitoring strategies need to be improved and different techniques such as in-situ measurements, remote sensing, satellite data and modelling must be combined to generate high quality products.

• Comprehensive and successful adaptation actions addressing disasters must be built on a robust foundation of the best available understanding of current and future glacier evolution. The modernisation of hydrometeorological networks and disaster response capacities, as well as actions by humanitarian agencies and research organisations contribute to risk reduction.

• Despite their critical role in environmental sustainability, national adaptation policies rarely recognise the unique problems and challenges related to glaciers. Laws written specifically to protect glaciers have only recently been considered within national political agendas. For instance, Argentina became the first country in the world to adopt a Glacier Protection Act in 2010. Given the importance of glaciers for water security, approaches and strategies for integrated water resources management should be developed and updated, taking into consideration new information and trends on glaciers.

• Lack of sustainable funding is among one of the most prevalent issues hampering the effective protection and management of all World Heritage Sites. Hence, there is an acute need to bridge the funding gap to successfully implement actions for the effective monitoring of glaciers, notably through the establishment of an international fund for glaciers to support comprehensive research and develop effective response measures.

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