Paris (AFP) - From Amazon rainforests to the Arctic Circle, indigenous peoples are leveraging ancestral knowhow to protect habitats that have sustained them for hundreds and even thousands of years, according to a landmark UN assessment of biodiversity released Monday.

But these "guardians of nature" are under siege, warns the first major UN scientific report to fully consider indigenous knowledge and management practices.

Whether it is logging, agribusiness and cattle ranching in the tropics, or climate change warming the poles twice as fast as the global average, an unrelenting economic juggernaut fuelled by coal, oil and gas is ravaging the natural world, the grim report found.

A million of Earth's estimated eight million species are at risk of extinction, and an area of tropical forest five times the size of England has been destroyed since 2014.

"Indigenous peoples and local communities are facing growing resource extraction, commodity production, along with mining, transport and energy infrastructure," with dire impacts on livelihoods and health, the report concluded.

Experts estimate that there are some 300 million indigenous people living in mostly undisturbed natural areas, and another 600 million in "local communities" straddling the natural and built worlds.

At least a quarter of global lands are traditionally owned, managed or occupied by indigenous groups, the UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) found.

- Pushing the boundaries -

"Indigenous peoples have truly been guardians of Nature for the rest of society," Eduardo Brondizio, co-chair of the UN report and a professor of Anthropology at Indiana University Bloomington, told AFP.

Research has shown, for example, that forests under indigenous management are more effective carbon sinks and are less prone to wildfires than many so-called "protected areas" controlled by business concessions.

"We have been guardians of our lands for millennia and have deep interaction with ecosystems where we live," said Lakpa Nuri Sherpa, a Sherpa activist from eastern Nepal.

"Our lands are among the most biodiverse on the planet."

But nearly three-quarters of regions worldwide under indigenous stewardship have seen a decline in most measure of biodiversity and ecosystem health, the report found.

"The pressures on them continue to be enormous," said Brondizio.

"The global economy keeps pushing the boundaries of resource extraction" deeper into indigenous territory, he said.

"Indigenous peoples have been retreating from those economic frontiers for 500 years, but get caught every time."

Globally, the pace of deforestation is staggering.

Last year, the tropics lost an area almost the size of England, a total of 120,000 square kilometres (46,000 square miles).

Almost a third of that area, some 36,000 km2, was pristine primary rainforest.

- Timber traffickers -

In Brazil -- home to nearly half of the world's plant and animal species -- landowners fell multi-storied trees to make way for soya bean crops, rogue miners pollute rivers, and timber traffickers steal valuable species.

"It is like using the goose that lays golden eggs to make soup," said Brondizio.

The livestock industry is a double climate threat: it destroys forests to make way for grazing land and soy crops to feed cattle, and generates huge amounts of methane, a potent greenhouse gas.

Extraction industries of all kinds have found an ardent backer in far-right President Jair Bolsonaro, who came into office in January.

"I am worried," said Brondizio, who is Brazilian, noting the weakening of environmental protections and an increase in the vilification of indigenous peoples.

Everywhere in the tropics, local populations that push back against big business and their backers are at risk.

More than 200 environmental campaigners -- half from indigenous tribes in tropical forests -- were murdered in 2017, according to watchdog group Global Witness.

"Our global home is under threat, and Nature is in decline, all driven by an economic and political system that favours increasing consumption and growth over living in harmony with Nature," said Aroha Te Pareake Mead, a member of the Ngati Awa and Ngati Porou Maori tribes in New Zealand.

https://www.yahoo.com/news/indigenous-peoples-guardians-nature-under-siege-235931504.html