In Brazil, natural conditions caused the problem, but mismanagement of already-thin water resources didn't help. Governors were reticent to restrict water use, especially ahead of the elections earlier this month, and, instead, most officials publicly banked on the rainy season coming to ease the pain. The typical rains that start in late September and October, however, haven't come.
The arid conditions aren't just plaguing the large southern cities, but are also being mirrored in the Amazon rain forest. A 2005 "mega-drought" saw a swaths of forest twice the size of California go dry, reversing the Amazon's traditional role as a carbon sink (instead of absorbing carbon dioxide, rotting trees emitted it). NASA researchers say the effects of that drought are still being felt and persisted until the start of the most recent drought in 2010.
And with deforestation rising again last year—up 29 percent in 2013 after years of declines—the lack of rain is likely to continue. The rain forest effectively acts as a pump for the country, absorbing moisture and releasing it through humid air that generates rain.
"It's a simply hydrological equation," said Michael Coe, director of the Amazon Program at the Woods Hole Oceanographic Institution. "The less evaporation there is, the less water there is for rainfall. We estimate that anywhere from a third to half of the rain that falls is coming from this evaporation."
Coe said it's unclear how much deforestation was directly contributing to dryness in the southern states but said it "could not be ruled out."
What is clear to the country's environmentalists is that a historic reliance on hydropower over other alternative energy sources has left Brazil desperate at a time of need. Brazil held a wind-only energy auction in 2009 that contacted more than 1,800 megawatts of capacity, a bid to diversify. Brazil's Energy Research Agency told Bloomberg last month that the country also planned to purchase 17 gigawatts of wind power over the next decade, while also boosting the meager solar power capacity.
Claudio Maretti, director of the World Wildlife Fund's Living Amazon Initiative, said that diversification is long overdue, especially as new hydroelectric projects become more expensive and carry greater environmental impacts. Maretti said that it's ironic in a country that offers so much choice for telecom companies that power remains so inflexible.
"Why can't I, in my home, choose where to buy power even if I have to pay a higher price?," said Maretti. "We need to be talking about how to improve our grid supply instead of discussing how to build one more dam or getting oil offshore."
Carlos Klink, Brazil's climate-change minister, said that the power emissions were unfortunate, but that the government was working to diversify. More than that, he said, it offers a learning experience on how to cope with the kind of extreme weather that is possible as the climate changes.
"This gives us a flavor of what might come," Klink said in an interview. "We're seeing that we have to do more adaptation for the regional and local level, and we're asking everyone to get involved
Jason Plautz reported from Brazil on a fellowship from the International Reporting Project (IRP).