November 14, 1995 in Nation/World

World Faces Loss Of Diverse Species Humans Accelerating Natural Extinction Rate

Heather Dewar Knight-Ridder
 

In the United States, the price of a fish dinner keeps going up, up, up as the North Atlantic is fished nearly dry. In the Amazon, malaria cases have skyrocketed after forest-clearing caused an explosion of disease-bearing mosquitoes. In Southeast Asia, flooding has wiped out entire towns because the mangrove forests that once acted as natural buffers have been reduced by half.

And all over the world, deadly diseases are going unchecked because the natural medicines that could save lives simply have vanished before their benefits could be discovered.

The natural wealth that scientists call biodiversity is disappearing at an “unprecedented” and alarming rate - roughly 1,000 times faster than the natural rate of extinction, according to a new study compiled by 1,500 scientists worldwide for the United Nations Environment Program.

If humans do not act to slow “the downward spiral” to extinction, onetwentieth to one-fifth of all living things are in danger of disappearing, with grave, unpredictable results for humankind, say the authors of the massive study.

The 1,100-page report, “Global Biodiversity Assessment,” was made public Monday in advance of a United Nations-sponsored conference in Jakarta, Indonesia. It is the first attempt at a worldwide assessment of Earth’s living resources, according to Tony Janetos, one of the editors.

It is an enterprise fraught with peril, since most of the world’s plants and animals are still unknown to science. Even the total number of species is a matter of doubt, with estimates ranging from 5 million to 80 million worldwide. The U.N. scientists agreed that Earth is probably inhabited by 13 million to 14 million different kinds of living things. But fewer than one in six, or 1.75 million, have even been named and described so far.

Since the start of the 19th century the best-known species, the flowering plants and higher animals, have been disappearing 50 to 100 times faster than they did in prehistoric times, the scientists said. By conservative estimates, 112 kinds of birds and mammals have gone extinct in the last two centuries.

“Tens of thousands of species are already committed to extinction,” the scientists wrote. “It is not possible to take preventive action to save all of them.”

The decline in diversity is “very dramatic” and “outside the range of anything experienced before,” including the mass extinctions of prehistoric times, said Janetos, director of the National Aeronautics and Space Administration’s land use program.

“There’s no doubt that humans are the primary factor behind the change,” Janetos said, “and yet humans are still dependent on the natural world for survival … In a sense, biodiversity is like humanity’s capital. You try not to spend capital if you don’t have to, and if you do have to, you try to understand the consequences first.”

The single greatest cause of extinction, the report concludes, is conversion of wilderness into farm fields.

Since 1700, the world’s cropland has increased fivefold. Some landscapes have been especially hard-hit: 98 percent of the dry forests on Central America’s Pacific coast are gone. So are 90 percent of Brazil’s Atlantic forest, half of Thailand’s mangroves and 54 percent of the United States’ wetlands.

As those habitats vanish, so does the natural variety they contain. Today, 90 percent of the world’s food supply comes from just 100 plant species, while thousands of other sources of food and medicine are ignored or obliterated. And increasingly, those 100 species are bred for high yields and ease of farming - weakening their ability to overcome diseases or changes in climate. It’s a state of affairs that leaves humans vulnerable to calamity, the report warns.

MEMO: Cut in the Spokane edition.

Cut in the Spokane edition.

Get stories like this in a free daily email


Please keep it civil. Don't post comments that are obscene, defamatory, threatening, off-topic, an infringement of copyright or an invasion of privacy. Read our forum standards and community guidelines.

You must be logged in to post comments. Please log in here or click the comment box below for options.

comments powered by Disqus