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Past century sees biodiversity dive

May 20, 2005 By Michael Hopkin This article courtesy of Nature News.

The latest of the Ecosystem Assessment reports is bad news.

Biodiversity is disappearing faster than ever, according to a report backed by the United Nations. Without action to curb the rate of ecosystem damage, its authors argue, the health and livelihoods of people around the world could be under threat.

Humans have done more damage to the world's stock of biological diversity in the past 50 years than at any other time in history, say the researchers behind the study, titled Ecosystems and Human Well-being: The Biodiversity Synthesis Report. Over the past century, species extinctions have reached about 1,000 times their natural rate, because of human actions.

Unless this trend is halted, people will lose vital benefits from the natural world, dubbed 'ecosystem services', said Kaveh Zahedi at the report's launch in London on 19 May. "Everyone depends on nature for a secure livelihood," said Zahedi, who is head of the UN Environment Programme's World Conservation Monitoring Centre in Cambridge, UK.

Some 3.5 billion people around the world depend on the oceans for food, added Jim Knight, the recently appointed British government minister with responsibility for biodiversity issues. But since the advent of commercial fishing, global fish stocks have plunged by up to 90%. Around 70% of the world's population still rely on nature for traditional medicines, he added.

Millennium plan

We know biodiversity has value, but we've been bad at assessing what that value is.
Georgina Mace
Institute of Zoology, London
The report is the latest in a series arising from the Millennium Ecosystem Assessment, a four-year project to catalogue data on the world's natural resources that involves more than 1,300 scientists. It reveals that 12% of bird species, almost a quarter of mammals and around a third of the world's amphibians are facing extinction.

This is largely due to destruction of natural ecosystems such as grasslands and forests, says Georgina Mace, one of the report's authors and director of science at the Institute of Zoology in London. She adds that 10-20% of the remaining resources are due to be converted to other land uses, such as agriculture, by 2050.

But there have been some successes, Mace says. In Europe, for example, financial incentives to encourage farmers to set land aside as a refuge for natural plants, birds and insects, have allowed biodiversity in farmland to bounce back.

This shows that economics is the key to achieving similar feats across the world, she argues. "We know biodiversity has value, but [in the past] we've been bad at assessing what that value is."

The report's authors have put a price tag on the environment to support their argument. They calculate, for example, that an intact hectare of mangrove forest is worth more than US$1,000 to a country such as Thailand, and only $200 when farmed intensively.

Disputed goal

However, the report has raised fears that efforts to protect biodiversity may be at odds with the UN Millennium Development Goals, first among which is to stamp out world poverty and hunger. Some economic analysts argue that this cannot be achieved without an increase in intensive farming.

"There are trade-offs to be worked through," admits Mace. "The issue is recognizing that there are no win-wins."

Zahedi points out that another of the Millennium Development Goals calls for environmental sustainability, arguing that, in cases such as fisheries, efforts to preserve biodiversity are not in conflict with the need to ensure a continuing food supply.


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