We humans are using the Earth to improve our lives, but our children and grandchildren will be forced to live in a deteriorating environment...

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We humans are using the Earth to improve our lives, but our children and grandchildren will be forced to live in a deteriorating environment that endangers their existence, more than 1,300 scientists warn.

In a report this week, a team of international experts concluded that the world is at risk on a variety of fronts, including a skyrocketing runoff of nutrient-rich farm waste that’s killing swaths of the world’s oceans, a massive wave of animal and plant extinctions and a planet that’s growing warmer.

But it’s not hopeless, the scientists said.

The five-year study, commissioned by the United Nations and a number of businesses and independent groups, arrived at a mixed prognosis for planet Earth: Its deteriorating environmental health is treatable, but only with aggressive and expensive corrective measures.

In the 219-page report, scientists looked at 24 “services” the Earth’s ecosystem provided and found that 15 are in trouble.

“At the heart of this assessment is a stark warning,” the board overseeing the report wrote. “Human activity is putting such a strain on the natural functions of Earth that the ability of the planet’s ecosystem to sustain future generations can no longer be taken for granted.”

The Millennium Ecosystem Assessment:

www.millenniumassessment.org


Increased demand for food, fresh water, energy and raw materials is weakening the delicate but complex systems of plants, animals and biological processes that make Earth livable, warned the report, released Wednesday.


What’s gone wrong



Ecosystems being drained or degraded largely in the pursuit of human well-being include:

Land: More of it has been converted to cropland since 1945 than in the 18th and 19th centuries combined. Cultivated land covers one-quarter of Earth’s land surface.

Coral reefs: About 20 percent of the world’s coral reefs were lost and another 20 percent degraded in the past few decades.

Rivers and lakes: Although the amount of fresh water stored behind dams has quadrupled since 1960, its use for agriculture and other needs has exceeded long-term supplies by 5 to 25 percent.

Coastal areas: Farmers’ increased use of nitrogen fertilizers since 1985 has polluted waterways and coastal ecosystems. About 35 percent of mangrove swamps needed for water filtration in coastal areas have been bulldozed.

Oceans: Many areas have been overfished, reducing stocks by 90 to 99 percent of preindustrial fishing levels.

Source: Millennium Ecosystem Assessment

The Christian Science Monitor


What makes this study — the Millennium Ecosystem Assessment — different from others is that it’s based on evidence generally agreed upon by scientists, rather than facts of the “he-said, she-said” variety, according to study executive director Walter Reid, an ecologist.

The study was compiled by 1,360 scientists from 95 nations who pored over 16,000 satellite photos from the U.S. National Aeronautics and Space Administration and analyzed statistics and scientific journals. Their findings highlight the planet’s problems at the end of the 20th century, as the human population reached 6 billion.

Aimed at business and government leaders, the report is often written not in the scary language of an environmental polemic but as a financial ledger for Earth. The scientists repeated the analogy of a person overspending his resources. “What we’ve been doing now is running down the account, if you will,” said Oregon State University zoology professor Jane Lubchenco, president of the International Council for Science. “We’ve been utilizing services assuming that they were free and would always be available.”

World Bank chief scientist and study co-chairman Bob Watson said that unless humankind changes its ways, consumption will “undermine the very ability for these ecosystems to provide the goods and services we need.”

Poorer countries will pay the steepest price, Watson said. Much of the problems surround water or the lack of it, a situation particularly acute in poor countries.

Nitrogen and phosphate runoff from farms is creating “dead zones” in oceans around the world and the problem is likely to increase by two-thirds by 2050, the report found. There are more than 50 dead zones, including in the Gulf of Mexico, Chesapeake Bay and Puget Sound, caused by an abundance of nutrients choking off oxygen, Lubchenco said.

More than one-quarter of the world’s wild-fish stocks are overharvested. For example, the number of Atlantic cod caught off Newfoundland’s east coast went from more than 800,000 tons a year in the 1960s to none. Cod fishing was halted after the stock of fish collapsed.

“We always have this sense that if we just let up on overfishing for a while, the fish will bounce back,” said Tundi Agardy, lead author on the coastal chapter of the report. “But what we found is that, many times, the recovery of overexploited species is made impossible by all sorts of things like pollution, habitat loss and climate change.”

More than 2 billion people live in “dryland ecosystems,” which hold one-third of the world’s population but only 8 percent of the renewable water supply. Unable to keep up with the demand for water, these regions will become poorer and their political institutions will become more unstable, the report said.

Most species are seeing populations drop. The report said 32 percent of amphibian species, 25 percent of mammals and 12 percent of birds are threatened with extinction in the next century.

By 2050, the world won’t be able to feed everyone, despite better farming, the report predicted. Add the prospect that global warming will worsen, making it harder for some species to survive.

Computer models showed that some of the report’s proposed changes fixed some problems (see “How to fix it”), said University of Wisconsin, Madison, zoology professor Stephen Carpenter, a co-author. “There are quite a few things that we could be doing to make things better, but we’re not doing any of them.”

Material from The Christian Science Monitor and The Associated Press is included in this report.