The World Heritage Convention laid down by the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1972 provides the basis for the designation and management of World Heritage Sites. According to article 11.4 of the convention, UNESCO, through the World Heritage Committee, may place threatened World Heritage Sites whose conservation require major operations and for which "assistance has been requested" on a List of World Heritage in Danger. This action is intended to increase the international awareness to the threat and to encourage counteractive measures. Threats to a site can be either ascertained dangers which are proven imminent threats or potential dangers that could have adverse effects on the characteristics of a site.
In the case of natural sites, ascertained dangers include the serious decline in the population of an endangered or other valuable species or the deterioration of natural beauty or scientific value of a property by man-made activities such as logging, pollution, human settlement, mining, agriculture and major public works. Ascertained dangers for cultural properties include serious deterioration of materials, structure, ornaments or architectural coherence and the loss of historical authenticity or cultural significance. Potential dangers for both cultural and natural sites include development projects, armed conflicts, insufficient management systems or changes in the legal protective status of the property. In the case of cultural sites gradual changes due to geology, climate or environment can also be potential dangers.
Before a property is inscribed on the List of World Heritage in Danger, its condition is assessed and a potential programme for corrective measures is developed in cooperation with the state party involved. The final decision about inscription lies in the hand of the committee. Financial support from the World Heritage Fund may be allocated by the committee for listed properties. The state of conservation is reviewed on a yearly basis. Depending on the outcome of the review, the committee may request additional measures or delete the property from the list if the threats ceased to exist or may consider deletion from both the List of World Heritage in Danger and the World Heritage List. Of the two former sites, the Dresden Elbe Valley was delisted after placement on the List of World Heritage in Danger while the Arabian Oryx Sanctuary was directly delisted. As of 2012, there are 38 entries (17 natural, 21 cultural) on the List of World Heritage in Danger. Many of the listed sites are located in the developing world with 17 in Africa (of which five are in the Democratic Republic of the Congo), 9 in Asia, 8 in the Americas and 4 in Europe. The majority of endangered natural sites (12) is located in Africa.
While danger listing has sparked conservation efforts and released funding, resulting in a positive development of some sites such as Galápagos or Yellowstone, the list itself and UNESCO's implementation of it have been the focus of criticism. In particular state parties and other stakeholders of World Heritage Sites have questioned the authority of the Committee to declare a site in danger without their consent. Until UNESCO set a precedent in 1992 placing several sites on the danger list against their view, state parties would have first submitted a program of corrective measures before a site could be listed. Instead of being used as intended, the List of World Heritage in Danger is perceived by some states as a black list and according to Christina Cameron, Professor at the School of Architecture, Canada Research Chair on Built Heritage, University of Montreal, has been used as political tool to get the attention of state parties. The International Union for Conservation of Nature (IUCN) notes that UNESCO has referenced the List of World Heritage in Danger (without actually listing the site) in a number of cases where the threat could be easily addressed by the state party. The Union also argues that listing a site as endangered over a long period of time is questionable and that other mechanisms for conservation should be sought in these cases.