Despite international protections, industrial activity threatens nearly half of all natural world heritage sites. The World Wildlife Fund (WWF) has released a report that says some 114 of the total 229 sites are slowly being destroyed by activities such as mining, oil exploration, overfishing and illegal logging. 

The 229 heritage sites include Australia's Great Barrier Reef, the U.S. Grand Canyon, China's giant panda sanctuaries in Szechuan, Machu Picchu, Egypt's pyramids and Florida's Everglades National Park - to name a few. These iconic habitats, rich with culture, history and refuge for endangered animals, are all supposed to be protected under the United Nations' designated world heritage status. 

"Even this small fraction of our planet is not receiving the protection it deserves," said David Nussbaum, chief executive of WWF-UK. "These areas contribute to our economies through tourism and natural resources, providing livelihoods for millions of people, while also supporting some of the planet's most valuable ecosystems."

The livelihoods of some 11 million people are directly dependent on the preservation of these sites, as they provide food, fresh water, shelter, and medicine, according to the report. What's more is over 90 percent of the natural world heritage sites provide jobs for residents, without which they would have no source of stable income. 

The United Nations Educational, Scientific and Cultural Organization (UNESCO) classifies world heritage sites as either cultural, natural or mixed.

A natural heritage site is one with outstanding physical, biological and geological formations, including the habitats of threatened plant or animal species, and areas with scientific, conservation or aesthetic value. Cultural heritage refers to sites with historical, aesthetic, archaeological, scientific, ethnological or anthropological value, such as monuments. Lastly, mixed heritage refers to sites including both cultural and natural criteria.

UNESCO lists 197 natural and 32 mixed heritage sites in 96 countries around the world, alongside 802 cultural sites. Together, the 229 natural and mixed sites account for more than a fifth of all UNESCO world heritage sites.

Within the sites at risk, the report said oil or gas concessions had been granted in 40 and mining allowed in 42. It also indicated that 28 sites are threatened by the construction of dams or unsustainable water use; another 28 are at risk of illegal logging; two from overfishing; and 20 from road or railway development. What's worse is that many of the sites are believed to be in danger of more than one of these threats. 

World heritage sites are are meant to be protected for future generations, and under the World Heritage Convention, the countries in which the respective sites lie are responsible for preserving them. 

"Despite the obvious benefits of these natural areas, we still haven't managed to decouple economic development from environmental degradation," WWF director general Marco Lambertini said. "Instead, too often, we grant concessions for exploration of oil, gas or minerals, and plan large-scale industrial projects without considering social and environmental risks."