Forests in question

As world warms, scientists try to solve Amazon puzzle

MANAUS, BRAZIL. Julio Tota stood atop a 195-foot steel tower in the heart of the Amazon rain forest, watching “rivers of air” flowing over an unbroken green canopy that stretched as far as the eye could see.

These billows of fog showed researcher Tota how greenhouse gases emitted by decaying organic material on the forest floor don’t rise straight into the atmosphere, as scientists had supposed.

Instead, they hover and drift — confounding scientific efforts to unlock the secrets of the world’s largest remaining tropical wilderness.

“What we’ve learned is the Amazon rain forest is much more fragile and much more complex than we had first imagined,” Tota said. “My research is pretty specific. It’s aimed at showing why all our measurements are probably off.”

Tota is part of the Large Scale Biosphere-Atmosphere Experiment, a decade-old endeavor involving hundreds of scientists, led by Brazilians and with funding from NASA and the European Union. Their open-air “laboratories” are 15 such observation posts spread over an area of rain forest larger than Europe.

The project’s goal is to make the best scientific arguments for why this vast rain forest — along with other endangered forests in Africa, southeast Asia and elsewhere — is essential to combating global climate change.

But, as the first phase of the $100 million experiment draws to a close, its researchers acknowledge that the data have raised more questions than answers.

Scientists can now say with certainty that the Amazon is neither the lungs of the Earth nor the planet’s air conditioner.

But a key question remains unanswered: Does the Amazon work as a net carbon “sink,” absorbing carbon dioxide, or is it adding more CO2 to the atmosphere than it is subtracting because of burning and other deforestation that has claimed an average 8,000 square miles — an area the size of Israel or New Jersey — each year of the past decade?

Scientists also can’t predict every way in which continued destruction of the Amazon — for timber, for cattle ranching, for soybean farming — might affect global climate. But it will almost certainly lead to drier conditions over a wide area, since ground moisture taken up and evaporated through trees is recycled as rainfall.