In this 30 October 2014 photo, cracked earth is seen at the almost empty Itaim dam, which is responsible for providing water to the Itu metropolitan area in Itu, Brazil. The government is preparing a study to measure the impact deforestation has had over recent decades, Environment Minister Izabella Teixeira said in an interview. Photo: Andre Penner / AP Photo

4 December 2014

SÃO PAULO (Associated Press) – Vera Lucia de Oliveira looks to the sky, hoping for any sign of rain.

For weeks, the taps in her home have run dry as São Paulo has suffered its worst drought in eight decades, with rainfall at one-third the normal level. Without heavy and prolonged rain, the megacity of 23 million could soon run out of water, experts warn.

"We are always thinking: The rain is coming, the rain is coming," said Oliveira.

But it doesn't, and a growing consensus of scientists believes the answer to what is happening to Oliveria and her neighbors lies not in the sky above their heads but in decades of deforestation of Amazon rainforest hundreds of miles away.

The cutting of trees, scientists say, is hindering the immense jungle's ability to absorb carbon from the air — and to pull enough water through tree roots to supply gigantic "sky rivers" that move more moisture than the Amazon river itself. More than two-thirds of the rain in southeastern Brazil, home to 40 percent of its population, comes from these sky rivers, studies estimate. When they dry up, drought follows, scientists believe.

It's not just Brazil but South America as a whole for which these rivers in the sky play a pivotal meteorological role, according to a recent study by a top Brazilian climate scientist, Antonio Nobre of the government's Center for Earth System Science.

The study draws together data from multiple researchers to show that the Amazon may be closer to a tipping point than the government has acknowledged and that the changes could be a threat to climates around the globe. His work is causing a stir in drought-stricken Brazil as environmental negotiators meet in neighboring Peru at the Dec. 1-12 U.N. climate talks.

Destruction of the Amazon went unchecked until 2008, when the government put teeth in its environmental laws and sent armed agents into the jungle to slow the pace of deforestation by ranchers, soy farmers and timber speculators. The impact was quick: Destruction in 2012 was one-sixth of what was recorded eight years earlier, though it has ticked up in the last two years.

But Nobre and other scientists warn it's not enough just to slow the pace of destruction — it must be halted.

"With each tree that falls you lose a little bit more of that water that's being transported to São Paulo and the rest of Brazil," said Philip Fearnside, a professor at the Brazilian government's National Institute for Research in the Amazon who was not part of Nobre's study. "If you just let that continue, you're going to have a major impact on the big population centers in Brazil that are feeling the pinch now."

U.S. scientists praise the study, with U.S. Geological Survey drought expert James Verdin calling it "compelling and credible." […]

Nobre's October report warned of the crucial need to replant one-fifth of jungle areas that were razed. In addition, 310 million acres, an area twice the size of France, have been degraded by patchwork destruction and need to be restored.

"We're like the Titanic moving straight toward the iceberg," Nobre said in a telephone interview. [more]

Deforestation may be at root of Brazil drought



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