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Putting the Squeeze on Earth

Almost half the land on the planet has been transformed by humans-in ways that include the filling of wetlands, the conversion of prairie to farmland or the replacement of forests with cities. That conclusion comes from a recent analysis of the latest research on the subject. Biologist Jane Lubchenco of Oregon State University presented the findings to more than 4,000 scientists at the International Botanical Congress in St. Louis in August. "As inhabitants of Earth, we need to take stock of these massive changes, understand their implications and change our direction," she said. "We are currently inattentive stewards. It is in our best interests to be more fully engaged in ensuring our own health, prosperity and well-being."

Among the other statistics compiled by Lubchenco and two colleagues, Harold A. Mooney and Peter M. Vitousek of Stanford University:

* Rates of extinction are 100 to 1,000 times what they would be without human-induced changes. On land, the accelerated rates are largely caused by habitat loss and species invasions.

* The coastal areas of the world's oceans contain an estimated 50 "dead zones," areas with little or no oxygen to support life.

* About 3,000 marine species are in transit in ballast water of ships around the world, resulting in a serious invasion of various nonnative species in our waterways.

* Excess fertilizer use and burning of fossil fuel has more than doubled the amount of available nitrogen in the environment. Nitrogen is a nutrient that in large amounts can unbalance ecosystems, causing problems such as blooms of algae.

Despite all the grim findings, Lubchenco found reason for hope: "It is encouraging that there is an increasing focus on the part of the private sector, religious groups and individual citizens to take responsibility and undertake innovative action."

# posted by Medical Information : 3:32 AM