The World Heritage List, maintained by the World Heritage Programme administered by UNESCO, includes 878 sites which are considered as having outstanding importance. Many sites have stood the test of time for hundreds, if not thousands of years, but some face a serious and imminent threat of destruction, either from natural disasters, armed conflict, the effects of climate change or tourism development. The World Heritage Committee has compiled an 'In Danger' short-list of 30 sites in order to inform the international community of the threat and to encourage corrective action.

While 30 sites out of 851 might not sound too alarming, a site that is not included in the In Danger list may still be at risk. The causes are often more insidious in nature or less obviously demanding of immediate response, and they include the impact of increasing tourism resulting in a continuous but gradual process of erosion or intrusion upon a site, commercial and residential sprawl, and the effects of climate change and the consequent risk of severe weather events. Nazca is not on the In-Danger list.