Deforestation may be at root of Brazil drought

In this Oct. 10, 2014 photo, the frame of a car is revealed by the receding water line in the Atibainha dam, part of the Cantareira System that provides water to the Sao Paulo metropolitan area, in Nazare Paulista, Brazil. The sky rivers are generated by the forest acting as a massive pump, according to research that has shown the jungles uniform humidity consistently lowers atmospheric pressure in the Amazon basin. That allows it to draw moist air currents from the Atlantic Ocean much farther inland than areas that dont have forests. Those currents travel west across the continent until they hit the Andes mountains, where they pivot and carry rains south to Buenos Aires and east to Sao Paulo. (AP Photo/Andre Penner)

FILE - In this Sept. 15, 2009 file photo, a deforested area is seen near Novo Progresso, in Brazil's northern state of Para. The "sky rivers" that flow from Brazil's immense Amazon jungle have long kept the nation's southeast a verdant green, a gift of nature that man has used to turn the area's lush, rolling hills into a breadbasket of farms, coffee plantations and thick pasture for cattle. While its too soon for scientists to say with certainty, there is a chorus of growing concern that Amazon deforestation has diminished those atmospheric flows, and that the jungle is nearing a permanent tipping point whereby it won't be able to sustain such rains in the future. Brazil's southeast is seeing a historic drought that has Sao Paulo, a city of over 20 million, on the brink of running out of water. (AP Photo/Andre Penner, file)

FILE - In this Sept. 15, 2009, file photo a forest in the Amazon is seen being illegally burnt, near Novo Progresso, in the northern Brazilian state of Para. The cutting of trees, scientists say, is hindering the immense jungles 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. (AP Photo/Andre Penner, file)

In this Sept. 17, 2009 photo, an environmental agent looks at his GPS device on an illegally deforested farm near Novo Progresso in the northern state of Para, Brazil. 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.(AP Photo/Andre Penner)

In this Oct. 30, 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. (AP Photo/Andre Penner)

In this Oct. 29, 2014 photo, a man exercises on the receding banks of the Guarapiranga dam, which is responsible for providing water to the Sao Paulo metropolitan area, in Sao Paulo, Brazil. Brazil's southeast is seeing a historic drought that has Sao Paulo, a city of over 20 million, on the brink of running out of water. (AP Photo/Andre Penner)