The Earth is on the brink of "major biodiversity crisis" fuelled by the steady destruction of ecosystems, a group of the world's most distinguished scientists and policy experts warn today.

Nineteen leading specialists in the field of biodiversity, including Robert Watson, chief scientist at the World Bank, and Professor Georgina Mace, director of the Institute of Zoology, are calling for the urgent creation of a global body of scientists to offer advice and urge governments to halt what they call a potentially "catastrophic loss of species".

Destruction of natural habitats and the effects of climate change are causing species to die out at 100 to 1,000 times faster than the natural rate, leading some scientists to warn we are facing the next mass extinction.

Nearly one-quarter of the world's mammals, one-third of amphibians and more than one-tenth of bird species are threatened with extinction. Climate change alone is expected to force a further 15%- 37% of species to the brink of extinction within the next 50 years.

Writing in the journal Nature today, the experts from 13 nations urge for the new body, the international mechanism of scientific expertise on biodiversity (Imoseb), to be set up to force better biodiversity policies around the world.

"We are on the verge of a major biodiversity crisis. Virtually all aspects of diversity are in steep decline and a large number of populations and species are likely to become extinct this century. Despite this evidence, biodiversity is still consistently undervalued and given inadequate weight in both private and public decisions," the authors say.

The new body will be modelled loosely on the Intergovernmental Panel on Climate Change (IPCC), a collection of the world's top climate scientists that is convened to assess the latest research on climate change and its potential implications. Because the IPCC is funded by governments, it carries sufficient clout to influence international and regional policy.

Dr Watson, a former chairman of the IPCC, said the Imoseb may face a tougher task than the IPCC because biodiversity is often more complex than climate change. An 18-month consultation is under way to agree how the body will accumulate scientific evidence, identify causes of damage and recommend ways to limit or reverse them.

In May, the World Conservation Union said the number of known threatened species stood at 16,119. Polar bears, desert gazelles and sharks were all added to the list of species facing extinction. Melting ice caps, hunting and over-fishing were identified as the culprits.

"Whether it's forests, marine systems, grasslands, you name it, they are in disrepair," said Dr Watson. "For the sake of the planet, the biodiversity science community has to create a way to get organised, to coordinate its work across disciplines, and together with one clear voice advise governments on steps to halt the potentially catastrophic loss of species already occurring."

In danger

- Great white shark populations have decreased by up to 95% in the past 50 years

- Polar bears are expected to suffer a population decline of 30% in the next 45 years

- Unregulated hunting and habitat degradation in the Sahara desert have caused an 80% drop in the dama gazelle population

- A quarter of freshwater fish in Africa is threatened by human activity