Amazon Losing "Flying Rivers," Ability to Curb Warming

Christine Dell'Amore in Copenhagen
National Geographic News
December 18, 2009

The Amazon's "flying rivers"—humid air currents that deliver water to the vast rain forest—may be ebbing, which could have dire consequences for the region's ability to help curb global warming, an expert said this week at the Copenhagen climate conference.

Rising temperatures in the Amazon region, in large part due to climate change, are creating more arid savannas, which disrupt the water cycle vital to Brazil's farming and energy industries.

Deforestation also plays a role. As more of Brazil's rain forests fall to logging and agriculture, there are fewer trees to release the water vapor that creates these flying rivers.

Until recently, Amazon forest loss has been primarily linked to the trees' role in trapping greenhouse gases, such as carbon dioxide (CO2), which are a root cause of global warming.

"Most people look at the Amazon as the lungs of the world, or as a solution to capture CO2," said Gérard Moss, an engineer and founder of the Flying Rivers Project, an ongoing effort to document the humid air currents and their effects.

"But I'd like people to realize that the Amazon Basin is a huge water pump—rain is [our] most valuable asset," he said by phone Wednesday in Copenhagen, where he gave a press briefing on the project earlier this week.

Flying rivers may transport as much water as the Amazon River itself, he added. "This huge rain machine needs to be preserved."

Watery World

The Amazon region is awash with fresh water: 3,700 cubic miles (15,400 cubic kilometers) falls from the sky each year, the highest rate of rainfall in the world. The runner-up is Russia, with a yearly rate of 1,900 cubic miles (7,800 cubic kilometers).

Flying Rivers Project scientists—led by agronomist and Amazon-rainfall expert Enéas Salati—have determined that a single large tree in the center of the Amazon forest can give off up to 317 quarts (300 liters) of water in a day. (See rain forest pictures.)

In a process called evapotranspiration, trees draw water from their roots and then "transpire" some of that water back into the air.

Since 2003, Moss has flown through Brazil's airborne rivers in a single-engine plane to collect water vapor samples. The vapor's chemical "footprints" are then analyzed at the Center for Nuclear Energy in Agriculture (CENA) in Piracicaba, in the state of Sao Paulo.

Continued on Next Page >>




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