The world must act immediately to stop the rapid loss of animal and plant species that allow humans to exist, the UN warned at a major summit on biodiversity.

Delegates from the 193 members of the UN’s Convention on Biological Diversity are gathering in the central city of Nagoya, Japan to try to work out strategies to reverse a man-made mass extinction.

“The time to act is now and the place to act is here,” CBD executive secretary Ahmed Djoghlaf said as the meeting opened, describing the 12-day event as a “defining moment” in the history of mankind.

“Business as usual is no more an option when it comes to life on earth... we need a new approach, we need to reconnect with nature and live in harmony with nature.”

Delegates were told human population pressures were wiping out ecosystems such as tropical forests and coral reefs, killing off animal and plant species that form the web of life on which humanity depends.

“This meeting is part of the world’s efforts to address a very simple fact. We are destroying life on earth,” the UN Environment Programme’s executive director Achim Steiner said in a speech at the opening ceremony.

“We are destroying the very foundations that sustain life on this planet.”

Delegates in Nagoya plan to set a new target for 2020 for curbing species loss, and will discuss boosting medium-term financial help for poor countries to help them protect their wildlife and habitats.

But similar pledges to stem biodiversity loss have not been fulfilled, and Mr Djoghlaf said governments around the world had to acknowledge that failure.

“Let’s have the courage to look into the eyes of our children and admit that we have failed individually and collectively to... to substantially reduce the rate of loss of biodiversity by 2010,” Mr Djoghlaf remarked.

“Let us look into the eyes of our children and admit that we continue to lose biodiversity at unprecedented rates.”

At the start of the decade, UN members pledged under the Millennium Development Goals to achieve “a significant reduction” in the rate of wildlife loss by 2010, the International Year of Biodiversity.

Instead, habitat destruction has continued unabated, and some experts now warn that the planet faces its sixth mass extinction phase – the latest since dinosaurs vanished 65 million years ago.

Nearly a quarter of mammals, one-third of amphibians, more than one in eight birds, and more than a fifth of plant species now face the threat of extinction, said the International Union for Conservation of Nature.

In May, a UN report warned of looming “tipping points” that could irreversibly damage ecosystems such as the Amazon rainforest, through logging and land clearance, and coral reefs through global warming and overfishing.

The earth’s 6.8 billion humans are effectively living 50 per cent beyond the planet’s biocapacity in 2007, according to a new assessment by WWF that said by 2030 humans will effectively need the capacity of two earths. Meanwhile, disputes between rich and poor nations that have plagued efforts to curb greenhouse gases threaten to similarly hamper biodiversity negotiations. The EU is calling for a target of halting biodiversity loss by 2020, while many developing nations only support a weaker goal of “taking action” on the issue.

Factbox

• UN members pledged under the Millennium Development Goals to achieve “a significant reduction” in the rate of wildlife loss by 2010, the International Year of Biodiversity. The UN admitted last month that this goal had been badly missed.

• Out of 44,838 species on the “Red List” of species compiled by the International Union for Conservation of Nature, 869 are considered to be extinct or extinct in the wild, while at least 16,928 are threatened with extinction.

• Nearly one-third of species of amphibians, more than one in eight birds, nearly a quarter of mammals and more than a fifth of plant species face the threat of extinction. Habitat loss, hunting, pollution, invasive species and climate change are the major culprits.

• Species that have recently been wiped out include the Alaotra grebe (Tachybaptus rufolavatus), a Madagascar water fowl that was killed by an introduced species of predatory fish and by nylon fishing nets. Species on the brink include a group of North Pacific right whales that has dwindled to about 30 individuals after massive slaughter in the 19th and 20th centuries.

• Biodiversity is not just about a species count but about the health of the food chain on which humans depend. In May, a UN report warned of looming “tipping points” that could irreversibly damage fundamental ecosystems such as the Amazon rainforest, through logging and land clearance, and coral reefs, through global warming and overfishing.

• Earth’s list of wildlife is still far from being documented, especially of species that live in the soil and in the deep ocean. This year, more than 200 previously unidentified species have been identified, including a white-tailed mouse and a tiny, long-snouted frog, found in remote islands off Papua New Guinea.

• There are also species that, once thought extinct, are rediscovered. Two species of African frog and a Mexican salamander thought to have been wiped out were found in remote habitat niches this year. And a study of 187 mammals that had been “missing” since 1500 found that 67 species had subsequently been found again.

Sources: IUCN, July 2009; IUCN and Kew Gardens study, September 2010; Global Biodiversity Outlook 3 (UN’s Convention on Biological Diversity), May 2010; Conservation International, September 2010; Proceedings of the Royal Society B: Biological Sciences, September 2010.