Historic Preservation (World Heritage Sites)

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Historic Preservation (World Heritage Sites)


World Heritage Sites (WHSs) are natural or architectural sites that are listed as having special value by the World Heritage Committee of the United Nations Educational, Scientific, and Cultural Organization (UNESCO). WHSs are protected under the 1972 international treaty known as the Convention Concerning the Protection of the World Cultural and Natural Heritage (World Heritage Convention, for short). As of 2007, there were 830 sites on the World Heritage list, spanning 138 countries, and the convention had been ratified by 183 states. Most of the sites (644) appear on the list due to their cultural value, while 162 are on the list for natural values, and 24 for a mixture of the two. All sites are iconic, that is, instantly recognizable by most persons as spectacular or significant, whether for natural reasons, cultural reasons, or both.

Historic WHSs, primarily buildings, neighborhoods, and archaeological sites, are threatened by climate change in a variety of ways, from damage to still-buried archaeo-logical evidence to erosion, salt weathering, inundation by rising seas, neglect by stressed human populations, and more. Adaptation to climate change at WHC sites is proposed by UNESCO not only for the sake of the particular sites, but to increase public awareness and willingness regarding adaptation in other settings.

Historical Background and Scientific Foundations

Cultural preservation efforts by international bodies were first made in the early twentieth century. The predecessor of the United Nations, the League of Nations, set up several groups for international cultural cooperation and preservation, including the International Museums Office in 1926. In 1931, this group convened a conference that produced the Athens Charter for the Restoration of Historic Monuments, the first international statement on the principles of historic preservation. (This Athens Charter is not to be confused with the famous Athens Charter of the 1933 International Congress for Modern Architecture.)

In 1937, the International Museums Office convened a Cairo conference on the principles of archaeological excavation. The United Nations replaced the League of Nations in 1945, and UNESCO was also founded that year. In 1956, the Cairo archaeological principles were taken by UNESCO as the basis for its recommendations for the preservation of archaeological sites.

The concept of a World Heritage Trust was advanced to the U.N. in 1965 by American preservationists. In 1968, Sweden offered to host a conference on the human environment at which such a trust would be discussed. In 1972, the proposed conference was held in Stockholm, the capital of Sweden. It was at this conference that the World Heritage Convention was drafted. The General Assembly of the United Nations approved it on November 16, 1972, creating the UNESCO World Heritage Center to administer the World Heritage List of sites. The World Heritage Center is overseen by the World Heritage Committee, a body of 21 member states elected for fixed terms (six years, prior to 2005; four years, since that time) by all the signatories of the World Heritage Convention.

Although climate change became a scientific concern in the 1970s, it was not until 2005 that the UNESCO World Heritage Center began to systematically consider the impacts of climate change on WHSs. A group of experts was convened by the center in March 2006 to assess climate impacts, and it issued its recommendations in July 2006. In addition to recommending adaptation measures that could be taken to protect WHSs, the committee urged that WHSs could also serve as “a useful tool to share and promote lessons learnt and best practices, as well as to raise awareness regarding climate change impacts using their iconic value.”

Threats to natural-value WHSs from climate change are numerous and direct. For example, the glaciers of Glacier National Park in the United States will likely be gone by 2030. A few of the ways in which historic sites are threatened by climate change include:

  • Buried archaeological evidence is preserved because it is in balance with local processes of chemistry, biological growth, and water flow (hydrology). Any changes to these processes can destroy or degrade archaeological sites.
  • Increased soil moisture may lead to greater salt mobilization from ground water into the walls of ancient buildings, leading to harmful crystallization on decorated surfaces.
  • Wood and other organic materials in buildings may be threatened by pests as bio-zones migrate with changing climate.
  • Increased flooding, storminess, wind, humidity, heat, and ultraviolet levels, forecast in many parts of the world as effects of climate change, can damage heritage structures.

For example, in the United Kingdom, government scientists have suggested that the water level of the Thames estuary in London may rise by 10–34 in (26–86 cm) by 2080. Under these conditions, the dike system that protects London from storm surges and extremely high tides, the Thames Barrier, is likely to be overflooded by about 2025, threatening damage to the Palace of Westminster and the Tower of London, both World Heritage Sites. Reconstruction of the barrier to deal with higher water levels is a possible adaptation to climate change.

The City of Chan Chan in the Andean Mountains of Peru is a site of about 5.4 sq mi (14 sq km) that records the high level of urban engineering achieved by the Chimor society. Its elaborate, decorated structures were built not of stone but of packed, dried earth, and are highly vulnerable to extreme precipitation events (unusually heavy rainfalls). Such events, associated with the El Niño weather cycles of 1982–1983 and 1997–1998, have already caused extensive damage to the Chan Chan ruins and such events are anticipated to become steadily more common under climate change. Groundwater levels, as determined by some 68 monitoring wells at the site, threaten the site from beneath and have been rising steadily.


EL NIÑO: A warming of the surface waters of the eastern equatorial Pacific that occurs at irregular intervals of 2 to 7 years, usually lasting 1 to 2 years. Along the west coast of South America, southerly winds promote the upwelling of cold, nutrient-rich water that sustains large fish populations, that sustain abundant sea birds, whose droppings support the fertilizer industry. Near the end of each calendar year, a warm current of nutrient-poor tropical water replaces the cold, nutrient-rich surface water. Because this condition often occurs around Christmas, it was named El Niño (Spanish for boy child, referring to the Christ child). In most years the warming lasts only a few weeks or a month, after which the weather patterns return to normal and fishing improves. However, when El Niño conditions last for many months, more extensive ocean warming occurs and economic results can be disastrous. El Niño has been linked to wetter, colder winters in the United States; drier, hotter summers in South America and Europe; and drought in Africa.

HYDROLOGY: The science that deals with global water (both liquid and solid), its properties, circulation, and distribution.

SALT MOBILIZATION: Movement of salt under, through, or on the surface of the ground, usually by water.

STORM SURGE: Local, temporary rise in sea level (above what would be expected due to tidal variation alone) as the result of winds and low pressures associated with a large storm system. Storm surges can cause coastal flooding, if severe.

ULTRAVIOLET: Light that vibrates or oscillates at a frequency of between 7.5 x 1014 and 3 x 1016 Hz (oscillations per second), more rapid than the highest-frequency color visible to the human eye, which is violet (hence the term “ultraviolet,” literally above-violet). Ultraviolet light is absorbed by ozone (O3) in Earth's stratosphere. This absorption serves both to shield the surface from this biologically harmful form of radiation and to heat the stratosphere, with important consequences for the global climate system.

WORLD HERITAGE CONVENTION: Treaty (the Convention Concerning the Protection of World Cultural and Natural Heritage) adopted by the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1972. Its goal is to encourage the protection of cultural and natural sites of “outstanding universal value.” Such sites are designated as World Heritage Sites.

WORLD HERITAGE SITE: A site deemed by the World Heritage Committee of the United Nations Educational, Scientific and Cultural Organization (UNESCO) to be of “outstanding universal value.” The site may be cultural, such as a building or neighborhood, or natural, such as a lake or mountain. Under the World Heritage Convention, the U.N. encourages (but cannot enforce) protection of World Heritage Sites.

In its 2007 report “Case Studies on Climate Change and World Heritage,” UNESCO also discussed the potential impact of climate change on other heritage sites, including: Cape Floral Region Protected Areas, South Africa;

Golden Mountains of Altai, Russian Federation; the Great Barrier Reef, Australia; Ichkeul National Park, Tunisia; Prague, Czech Republic; Quadi Qadisha and the Forest of the Cedars of God, Lebanon; Sagarmatha National Park, Nepal; Sundarbans, India and Bangladesh; Timbuktu, Mali; and Venice, Italy.

Impacts and Issues

Organizations supporting the preservation of historic buildings, neighborhoods, and archaeological sites have been established in many countries—for example, the National Trust for Historic Preservation in the United States. The same aspects of climate change that imperil WHSs are a threat to many of the sites that such national and local organizations seek to protect.

In July 2006, the UNESCO World Heritage Committee adopted a climate-change response strategy based on the recommendations of its expert committee. Controversy arose after the United States was elected to the committee in October 2005. The United States submitted a position paper casting doubt on climate change and opposing adaptations proposed by the committee. The paper argued that “There is not unanimity regarding the impacts, causes, and how to or if man can affect the changes we are observing.” The statement was technically correct: unanimity would only exist if there was not one dissenting voice, and dissenters from the scientific consensus on climate change do exist. However, that consensus position is affirmed by a large majority of the world's climatologists, meteorologists, and geophysicists.

The United States also argued that sites put forward for inclusion on the World Heritage in Danger list—sites especially endangered by climate change and other causes—should not be listed without the support of the governments of the countries where the sites are located, even though, as the U.S. position paper acknowledged, such a requirement is “not specifically articulated” in the World Heritage Convention. The United States argued that the World Heritage Committee should not address the issue of climate change at all, writing that “There is no compelling argument for the Committee to address the issue of climate change—especially at the risk of losing the unified spirit and camaraderie that has become synonymous with World Heritage.”

The U.S. position, while controversial, was unusual. Because the decisions of the 21-nation World Heritage Committee are taken by majority vote, the United States was unlikely to prevail in its efforts to keep certain nominated sites off the World Heritage in Danger list, including Mt. Everest and the Waterton-Glacier International Peace Park in Canada and the United States. Inclusion on the danger list would, according to the terms of the World Heritage Convention, require the World Heritage Committee to demand action for the preservation of the listed sites. Such action would include measures to mitigate climate change. The issue had not yet been decided as of November 2007.

See Also United Nations Environment Programme (UNEP).


Web Sites

“Case Studies on Climate Change and World Heritage.” United Nations Educational, Scientific, and Cultural Organization. World Heritage Center, 2007.<http://whc.unesco.org/documents/publi_climatechange.pdf> (accessed November 16, 2007).

“Predicting and Managing the Effects of Climate Change on World Heritage.” World Heritage Center, March 2006. <http://whc.unesco.org/uploads/activities/documents/activity-393-1.doc> (accessed November 16, 2007).

“USA Opposing World Heritage Action on Climate Change” (press release). Friends of the Earth, March 15, 2006. <http://www.foe.co.uk/resource/press_releases/usa_opposing_world_heritag_15032006.html> (accessed November 16, 2007).

“World Heritage Committee Adopts Strategy on Heritage and Climate Change.” World Heritage Center, July 2006. <http:// whc.unesco.org/en/news/262> (accessed November 16, 2007).

Larry Gilman

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Historic Preservation (World Heritage Sites)

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Historic Preservation (World Heritage Sites)