​Sydney, Jan 31 (IANS) Most of the over 100 natural World Heritage sites that are being severely damaged by expanding human infrastructure and land use are in Asia, a new study has warned.

India's Manas Wildlife Sanctuary and Nepal's Chitwan National Park are among the most impacted Natural World Heritage Sites (NWHS), the study, published in the journal Biological Conservation, identified.

"It is time for the global community to stand up and hold governments to account so that they take the conservation of natural World Heritage sites seriously," said lead author James Allan from University of Queensland in Australia.

"We urge the World Heritage Committee to immediately assess the highly threatened sites we have identified. Urgent intervention is clearly needed to save these places and their outstanding natural universal values," Allan added.

Natural World Heritage Sites (NWHS), via the formal process run by UNESCO (United Nations Educational, Scientific and Cultural Organisation), are globally recognised as containing some of the Earth's most valuable natural assets.

The authors looked at human pressure over time using the updated global Human Footprint criteria, which includes roads, agriculture, urbanisation and industrial infrastructure, along with forest loss.

They found that the Human Footprint has increased in 63 per cent of Natural World Heritage Sites (NWHS) across all continents except Europe over the past two decades. 

The most impacted NWHS were found in Asia. Even celebrated places like Yellowstone National Park in the US were impacted, losing some six per cent of its forests. 

Meanwhile, Waterton Glacier International Peace Park that crosses the Canadian and USA border lost almost one quarter of its forested area (23 per cent or 540 km2).

"Any place that is listed as a World Heritage site is a globally important asset to all of humanity," said senior author James Watson of the University of Queensland and Wildlife Conservation Society.

"The world would never accept the Acropolis being knocked down, or a couple of pyramids being flattened for housing estates or roads, yet right now, across our planet, we are simply letting many of our natural World Heritage sites be severely altered," Watson noted