Biodiversity in peril

Development & Ecosystems

Biodiversity in peril

Mirror image : A lone crocodile swims under the reflections of trees lining the Rio das Mortes or River of the Dead in Brazil's Amazon basin.  ( Damon Winter / The New York Times )

Nearly 80 per cent of the world’s population – 4.8 billion people as calculated in 2000 – live in areas experiencing a high level of threats to human water security or biodiversity. Water-management strategies aimed at improving human water security, such as building dams to provide access to water-starved regions, often detrimentally affects wildlife that also depends on freshwater resources, such as migrating fish.

But a study published in Nature is the first to consider factors affecting both human water security and biodiversity in its analysis of threats to global freshwater resources, such as pollution and the density of dams. “If you analyse water-security issues from both a human and biodiversity perspective, you find that the threats are shared and pandemic. Even rich countries, which you would expect to be good stewards of water, have some of the most stressed and threatened areas,” says Charles Vorosmarty, a civil engineer at the City University of New York, one of the lead investigators of the analysis.

“The study addresses one of the biggest issues affecting global water resources, and that is how to strike a balance between the need for water for human development and the need for water for other ecosystem services,” says David Molden, deputy director for research at the International Water Management Institute, based near Colombo in Sri Lanka.

Downstream effects

Vorosmarty and his colleagues carried out a computer-based assessment to quantify documented threats to human water security and freshwater biodiversity in global river systems. From this they produced a series of global maps showing the cumulative effect of the multiple threats.

One of the maps illustrates areas where human water security is affected, together with the severity of the threats. Another charts the same areas and threats for biodiversity, and a third map combines the two surveys.

The researchers found that regions of the world with intensive agriculture and dense human settlement, such as the United States and Europe, experience some of the highest levels of threats to both human water security and biodiversity.

In addition, the results show that local impacts are transported downstream, with more than 30 of the 47 largest rivers in the world, including the Nile, recording at least moderate threat levels at the river mouth. Only a small fraction of the world’s rivers are unaffected by humans, with remote parts of the Amazon that flow through dense rainforest showing the lowest levels of threats.

Trade-off

Through costly engineering solutions, developed countries can provide their populations with clean water.  But poorer countries such as China sometimes struggle with basic water provision, says Vorosmarty. He estimates that, by 2015, around US$800 billion will be required to cover the annual global investment in water infrastructure.Vorosmarty notes that technological solutions that help to deal with threats to human water security, such as building dams, can harm biodiversity. But he adds that there does not need to be a trade-off between providing people with water and protecting biodiversity.

For example, preserving flood plains rather than constructing flood-control reservoirs would provide a cost-effective way to control floods while protecting the biodiversity of wildlife that occupies such areas.“If you want to manage water resources better, you have to jointly manage biodiversity protection and human water security,” he says.

Natasha Gilbert, Nature News

China wakes up to biodiversity threat

Li Li wears military fatigues and leads a band of a dozen or so activists. He is the head of the Panther Protection of Wildlife Organisation. Li Li says his only motivation is to preserve the richness of China’s countryside. This country’s economy has seen remarkable growth in the last decade and it is on track to become the world’s second largest economy by the end of the year. But that economic development has come at a high cost as the country is now the world’s biggest polluter.

According to a World Bank report in 2007, 20 of the world’s 30 most polluted cities were in China. The country’s rich biodiversity – about 10 percent of the world’s – is increasingly under threat. “What we’ve seen in the last 30 years thanks to economic development has been a massive erosion of habitats and pressure on the species used in traditional Chinese medicine,” says Jonathan Watts, author of the book, When a Billion Chinese Jump. “By some estimates that species loss in China is 50-100 percent higher than the global average.” But China is beginning to wake up to the problem. It is a crisis that the country cannot ignore. Campaigns are being launched across the country, persuading people to become greener. The country is the world’s leader in terms of clean energy.

Every hour, a new wind turbine is erected, according to a new Greenpeace report. And Chinese companies are leading the way in green technology, such as the development of electrical cars. “I think the situation here is better than five years ago,” says Xi Yan, the director of the Wildlife Conservation Society in China.

Martin Patience, New York Times News Service

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