UNESCO World Heritage Sites in Danger of Global Warming

PARIS, France, April 10, 2007 (ENS) - The Great Barrier Reef, Kilimanjaro National Park, and The Tower of London are among the UNESCO World Heritage sites that will be threatened by climate change in this century, according to a publication by the UN agency released today.

The report, "Case Studies on Climate Change and World Heritage" is intended to raise awareness and mobilize support for preservation of the 830 natural and cultural sites inscribed on the UNESCO World Heritage List.

The UNESCO report follows the second of three global assessments by the UN's Intergovermental Panel on Climate Change, IPCC, released on Friday.


A herd of elephants in Kenya's Amboeseli National Park with Tanzania's Mount Kilimanjaro behind them. The mountain's famed ice fields are melting. (Photo credit unknown)
The latest assessment projects that human-caused global warming will produce droughts and floods across the world, that glaciers and ice sheets would melt, resulting in floods and rising sea levels as well as extreme weather events over the next century.

Today's publication of the UNESCO report follows a 2005 decision by the World Heritage Committee to start studying the impact of climate change on World Heritage sites.

In March 2006, 50 experts on the subject met at UNESCO and in July 2006 they presented the World Heritage Committee with predictions, suggestions for management of climate change impacts, and a strategy to assist the 183 countries that are Parties to the World Heritage Convention.

"The international community now widely agrees that climate change will constitute one of the major challenges of the 21st century," says the Director-General of UNESCO, Koïchiro Matsuura, in his Foreword to the publication.

Matsuura calls for "an integrated approach to issues of environmental preservation and sustainable development."

Divided into five chapters, the UNESCO report deals with the impact of global warming on glaciers, marine biodiversity, terrestrial biodiversity, archaeological sites, and historic cities and settlements. Lead author is Augustin Colette, climate change consultant to the UNESCO World Heritage Centre.


The melting of glaciers around the world is affecting the appearance of sites inscribed for their outstanding beauty and destroying the habitat of rare wildlife species such as the snow leopard and the red panda in Nepal's Sagarmatha National Park.

The park is an exceptional Himalayan high altitude landscape dominated by Mount Everest, the world’s highest mountain.


The Pattar glacier in Nepal's Sagarmatha National Park (Photo © J.M. Gassend / UNESCO)
It is now feared that the Himalayan glaciers are rapidly retreating because of climate change. Since the mid-1970s, the average air temperature rose by 1°C in the Himalayan region, almost twice as fast as the global average warming of 0.6 °C reported by the IPCC, this trend being most pronounced at high altitude sites.

Almost 67 percent of the glaciers in the Himalayan and Tienshan mountain ranges have retreated in the past decade – by as much as 30 meters per year for the Gangotri glacier.

Rapid melting of glaciers is already increasing the magnitude and frequency of catastrophic floods downstream. The continued melting will eventually affect the availability of life-giving water for drinking, food production, and ecosystem maintenance.

Changes in the atmospheric temperature and in the rate of rainfall will affect the equilibrium between the amount of precipitation stored in winter and the melt during summer.

The melting season of snow coincides with the rainy season in the Himalayas. Consequently, any intensification of rainfall is likely to contribute to the rapid disappearance of snow and ice.

These changes could have disastrous effects on human lives with flooding resulting from glacial lake outbursts threatening human settlements. The establishment of monitoring and early warning systems and the artificial draining of glacial lakes are recommended to help avoid disasters.

The global average temperature increase projected by the end of the century ranges from 1.4 to 5.8 degrees C. The UNESCO report states that a 4 degree C increase of atmospheric temperature would eliminate nearly all glaciers on Earth.

Marine Biodiversity

The report examines the effects of climate change on the marine World Heritage sites. Seventy percent of the world's deep sea corals, inhabited by hundreds of thousands of fish species, are expected to be affected by changing conditions related to rising temperatures and increased ocean acidification by the year 2100.

Australia's Great Barrier Reef, listed as a World Heritage Site in 1981, is expected to be subjected to increasingly frequent bleaching events, cases in which corals turn white and may die due to rising sea temperatures.


A glimpse of Australia's Great Barrier Reef (Photo © Great Barrier Reef Marine Park Authority)
The largest coral reef ecosystem in the world, 2,100 km in length, the Great Barrier Reef Lagoon contains 2,900 individual reefs with 400 species of corals, 1,500 species of fish and several thousand species of molluscs. It is the habitat of species such as the dugong and the green and loggerhead turtles, which are threatened with extinction.

According to model projections, warming in the Great Barrier Reef Region would be in the range of 2 to 5 degrees C by 2100. The most likely outlook is that mass bleaching events, leading to widespread death of corals, will become more frequent on the Australian coast in the coming decades.

IUCN-World Conservation Union estimates that 20 percent of the world's coral reefs have already been wrecked. A further 50 percent are facing immediate or long term danger of collapse, the IUCN said today at the opening of the IUCN Marine Protected Area Summit in Washington, DC.

"Governments and the conservation community need to step up marine protection if we are to support the global effort to tackle climate change," said IUCN Director General Julia Marton-Lefèvre.

"As Friday’s UN Climate Change Report stated, a sea temperature rise of 1-3 degrees C will be enough for a major decline in coral reefs, unless corals adapt to warmer waters. This acclimatization will only be possible if they are protected from other stresses such as pollution or overfishing," Marton-Lefèvre warned.

Intact coral reefs and mangroves act as natural barriers against storms and floods. Healthy marine ecosystems world-wide will be more resilient to climate change impacts such as coral bleaching and mortality, displacement of key species and overall decline in ecosystem quality if coral reefs remain intact.

Coral reefs provide livelihoods to 100 million people and provide the basis for industries such as tourism and fishing, worth an annual net benefit of US$30 billion.

Terrestrial Biodiversity

Biodiversity on land is also threatened by climate change, says the report, which features a detailed case study of the Heritage Site of Cape Floral Region Protected Areas, South Africa, where biodiversity is threatened by shrinking bioclimatic habitats - due to warming and changes in precipitation.

The Cape Floral Region represents less than 0.5 percent of the area of Africa but it is home to nearly 20 percent of the continent’s floral biodiversity. As such it is one of the richest areas for plants in the world. It displays the highest levels of endemism at 32 percent and it has been identified as one of the world’s 18 biodiversity hot spots, and due to its unique floristic values it is recognized as one of the world’s six floral kingdoms.


Cape Floral biome at South Africa's Table Mountain, a UNESCO World Heritage Site in the Western Cape Province. (Photo courtesy Government of South Africa)
According to the IUCN, experiments, observations and modeling show that climate change might be the most significant threat facing biodiversity in the Cape Floral Region over the next 50 to 100 years. The most threatening aspects of climate change are shrinking of optimal bioclimatic habitats with warming and potential drying; ecosystem changes in response to modification of environmental conditions; and increase of fire frequency.

As a result of these physical changes, four out of five protected areas in South Africa are predicted to lose 10 percent to 40 percent of their plant species by the year 2050. The first impacts of climate change on the biodiversity of the Cape Floral Region are already becoming apparent, UNESCO reports.

Climate change will force some plant and animal species to migrate as they are unable to adapt to their changing environments, which poses a problem for the conservation of biodiversity hotspots listed as natural World Heritage sites.

On the global scale, climate warming is expected to lead to changes in the distribution of species, including invasive pathogens and parasites and on the timing of biological events, such as flowering, and the relationships between predator and prey, parasite and host, plant and pollinator.

The report recommends several measures to deal with this problem such as the creation of protected areas. Another strategy is relocation of particularly endangered species either toward safer habitats in the wild, or by storing genetic resources in gene or seed banks, or in protected ex-situ conservatories.

Archaeological Sites

Climate change is also expected to damage archaeological World Heritage sites, according to the report which examines prospects for Chan Chan Archaeological Zone, Peru, alongside other World Heritage properties in Canada and the Russian Federation.

Changes in precipitation and drought cycles, in humidity, water-table levels and ensuing soil chemistry will, inevitably, impact the conservation of archaeological remains.

Likewise, temperature rises, especially the melting of permafrost in the Arctic region and rising sea levels are also expected to take their toll on this heritage.

The report analyses how rainfall and flooding related to the El Niño pattern of warming in the eastern tropical Pacific is undermining the fragile earthen fabric of Chan Chan, the largest pre-Hispanic city in South America. The remains of the capital of the ancient Chimu Kingdom, it is one of the most important early earthen architecture cities in the Americas.

"Of special concern for archaeological evidence, compared to any other type of properties, is the fact that climate change may jeopardize the conservation of precious evidences whose existence is even not known today," says the UNESCO report.


Monolithic lanzon of Chavin (Photo © Alejadro Balaguer / PromPeru)
The site of Chavín is the most significant and representative site of the Formative period, 1500 to 300 BC, in the Peruvian Central Andes. Its stone-faced platform mounds, terraces, and sunken plazas of this former place of worship are characterized by a series of subsurface galleries. It was inscribed on the World Heritage List in 1985, as an exceptional testimony of a civilization which has ceased to exist.

Chavín lies at the confluence of the Mosna and Wacheqsa rivers in the province of Huari, in a high valley on the eastern side of Peru’s Cordillera Blanca.

This site is located near the Natural World Heritage site of Huascarán National Park. As elsewhere in the world, glaciers are melting in this area, leading potentially to the formation of glacial lakes, and to glacial lake outburst floods.

No matter whether the trend is toward an increased frequency of droughts or floods, the UNESCO report says, changes in water-table levels, in humidity cycles, in time of wetness, in groundwater, and in soil chemistry will impact on the conservation of archaeological remains.

Historic Cities

Rising sea levels and flooding due to climate change could have a devastating effect on both the buildings and social fabric of historic cities and settlements, according to the report.

Climate change may lead to more frequent and intense flooding of the River Thames which flows through the City of London. The most significant flood threat to London arises from a combination of high tides and storm surges caused by low pressure systems travelling over the North Sea, and the funnelling of water from the southern North Sea into the Thames Estuary.

The UNESCO report finds that by the 2050s, a 34 cm rise in sea level at Sheerness changes the one in 1,000 year flood level, to a one in 200 year flood event. By 2100, it is estimated that the Thames Barrier will need to be closed about 200 times per year to protect London from tidal flooding.

Tower of London

The Tower of London is near enough to the Thames River to suffer flooding. (Photo © J. Didon / UNESCO)
Just one overtopping of the Thames Barrier will have an indirect cost blow to the British economy of £30 billion says the UNESCO report, which predicts that flooding will inundate at least the three World Heritage sites closest to the Thames - the National Maritime Museum, Greenwich, the Tower of London and the Palace of Westminster.

Rapid flowing waters will erode their walls, and post-flooding drying will favor the growth of damaging micro-organisms such as molds and fungi, the report warns.

Founded in the fifth century and spread over 118 small islands, Venice is threatened by the sea level rise that is projected to result from climate change. "The whole city is an extraordinary architectural masterpiece in which even the smallest palaces contain works by some of the world’s greatest painters such as Giorgione, Titian, Tintoretto, Veronese and other artists," the UNESCO report says.

The combination of local and global sea-level changes results in a net rising of the sea level in Venice. Out of the 10 highest tides between 1902 and 2003, eight have occurred since 1960. According to the moderate scenarios of climate change, the projected net altitude loss of Venice will reach 54 centimeters by 2100. If nothing is done, Venice could be flooded daily.

Prague in the Czech Republic is also threatened by flooding, but the ancient city of Timbuktu in Mali is in for a different kind of climate stress. The threats of sand encroachment and desertification are accompanied by extreme rain events.

In the recent past, the mud mosques in Timbuktu suffered severe damage from the heavy rains of 1999, 2001 and 2003 that caused the collapse of traditional earthen buildings.

Between 1901 and 1996, temperature increased by 1.4 degrees C in Timbuktu, and the impact of droughts is becoming significant. Projected changes show that in future the area will face a decrease in average rainfall, and an increase in atmospheric temperature, which will surely enhance desert encroachment and sandblown damage in Timbuktu.

The UNESCO report, "Case Studies on Climate Change and World Heritage," is online at: http://whc.unesco.org/documents/publi_climatechange.pdf