Loss of Amazon Rain Forest May Come Sooner Than Expected

National Geographic News
June 26, 2001

EDINBURGH, Scotland—While many environmental issues today are highly contentious, there's one cause that seems to unite nearly everyone: pleas to save the world's rapidly disappearing rain forests. Yet a new mathematical model suggests we may not be acting fast enough.

According to projections by a Penn State professor, Amazonian rain forests could reach a "point of no return" in as little as 10 to 15 years from now if deforestation continues at the present rate of about one percent a year.

The model further shows that rain forest in Brazil could be wiped out entirely within 40 to 50 years—much sooner than predicted in other studies, which have led many researchers to estimate that total rain forest loss won't happen until the end of this century, 75 or 100 years away.

James (Bud) Alcock, a professor of environmental sciences at the Abington campus of Penn State, reached these conclusions by constructing a mathematical model that used the two million-square-mile Amazon River Basin as an example.

Because moisture is critical to rain forest ecosystems, Alcock studied how the ecosystem responds to changes in natural climate cycles that occur over time when large areas of trees and vegetation are cleared for agriculture, logging, and mining.

"Because of the way tropical rain forests work, they are dependent on trees to return water to the air," he said, adding that about a quarter of the total rain forest in the Amazon River Basin has already disappeared.

The results showed that, with no action to curb the losses, the rain forest could become unsustainable—that is, unable to regenerate and thrive fast enough to maintain its unique ecosystem and the life it supports—within the next decade or so.

Alcock presented his findings June 25 at a joint conference of the Geology Society of America and the Geology Society of London in Edinburgh, Scotland.

Climate-Forest Connection

"The interdependence of climate and forest means risks to the forests are much closer at hand than what we might expect," said Alcock.

He explained: Rain forests require high levels of precipitation, which comes from rain. A healthy forest takes in that rain and returns it to the atmosphere so it can be recycled (a process called evapotranspiration).

Without a healthy base of vegetation, there is greater runoff of water. This upsets the balance of water circulation, which over time is likely to make a rain forest highly unstable.

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