PHOTOS: "Alarming" Amazon Drought

River's End
Photograph by Rodrigo Baleia, LatinContent/Getty Images
This gallery is part of a special National Geographic News series on global water issues .
Hard-hit by a months-long drought, a waterway within the Amazon Basin trickles to a halt in Manaus, Brazil (see map), on November 19.
The Negro River, a major tributary of the Amazon River, dropped to a depth of about 46 feet (14 meters)—the lowest point since record-keeping began in 1902.
(Related: "Amazon Losing 'Flying Rivers,' Ability to Curb Warming.")
About 60,000 people in the Amazon have gone hungry as falling river levels paralyzed transport and fishing. Millions of dead fish have also contaminated rivers, leading to a shortage of clean drinking water, the Reuters news agency reported. (How much do you know about drinking water? Test your knowledge with a quiz.)
Caused by El Niño—a cyclical warming of tropical waters in the central and eastern Pacific Ocean—such a severe drought usually occurs once in a century. But the 2010 disaster comes just five years after the latest Amazon "megadrought," according to Reuters.
The drought also fits within predictions of climatic extremes this century due to global warming, Reuters reported. (Explore an interactive map of global warming's effects.)
Published December 6, 2010
Stranded Boat
Photograph by Euzivaldo Queiroz, Acrõtica/AFP/Getty Images
A fisher works on his boat stranded on the Negro River in northern Brazil on October 22.
Droughts can actually contribute to greenhouse gas emissions. That's because the vast Amazon rain forest acts as a carbon sink, soaking up about two billion tons of atmospheric carbon a year, according to Reuters. But when trees die or wither—as occurred during the 2005 Amazon drought—the forest switches from a carbon sink to a carbon source.
(Related: "Amazon Opportunity: Brazil Doesn't Count on Carbon Market.")
For instance, the 2005 drought alone released more greenhouse gases than the annual emissions of Europe and Japan combined, Reuters reported.
(Related: "Amazon's Low Salt Content Keeps Carbon Emissions at Bay.")
Published December 6, 2010
No Day at the Beach
Photograph by Marcio Melo, A Critica/Reuters
Usually submerged by the Negro River, a bank under Manaus's Brito Bridge became a recreation spot on October 26.
But for most Brazilians, the drought is no walk in the park. With thousands of boats stranded on the parched riverbeds, many isolated communities have become dependent on emergency aid, according to Reuters.
(Read about the freshwater crisis in National Geographic magazine.)
Published December 6, 2010
Drought Victim
Photograph by Rodrigo Baleia, LatinContent/Getty Images
A boat lies deserted on the banks of the Negro River on the outskirts of Manaus on October 23.
Natural disasters in the Amazon have sparked an exodus of environmental migrants to cities in recent years.
"It's a consistency of extremes," Joao Messias, vice mayor of the small city of Manacapuru, told Reuters. "Our city here is literally full. It has filled up a lot after these big floods and droughts."
(See flood, drought, and climate change pictures.)
Published December 6, 2010
Rock Art Revealed
Photograph by Rodrigo Baleia, LatinContent/Getty Images
A fisher reportedly discovered prehistoric etchings, shown in this November 15 photo, when water receded from the banks of the Negro River, according to the Hindu newspaper. (See related blog: "Mysteries of Prehistoric Rock Art Probed.")
Archaeologists suggest the 7,000-year-old engravings—which feature images of faces and snakes—may be more evidence that the Amazon was once home to large civilizations, the Hindu reported.
(Also see "'Lost' Amazon Complex Found; Shapes Seen by Satellite.")
Published December 6, 2010
High and Dry
Photograph by Rodrigo Baleia, LatinContent/Getty Images
Fishers and other residents gather on the drought-affected banks of the Taruma River near Manaus on October 24.
In the small town of Caapiranga, also near Manaus, residents cut off from boat transport told Reuters that food had doubled in price since the drought began. Compounding the disaster, many farmers also said their cropland has yet to recover from 2009 floods.
(See related blog: "Expect More Floods as Global Water Cycle Speeds Up.")
Published December 6, 2010
Lone Traveler
Photograph by Rodrigo Baleia, LatinContent/Getty Images
A boat squeezes through a narrow channel near Manaus on November 5.
Desperate for food, some residents have scooped up rare manatees from shallow rivers, Reuters reported.
(See pictures of conflict due to freshwater shortages around the world.)
Published December 6, 2010
Drought Debris
Photograph by Rodrigo Baleia, LatinContent/Getty Images
A boat rests amid debris in Manaus on September 15.
The drought has also sparked a surge in wildfires, particularly in the state of Mato Grosso—which means "thick forest," according to Reuters.
There have been 36,700 forest fires in Mato Grasso so far this year, compared with 8,135 in 2009, Reuters reported. The blazes have destroyed cattle pastures, killed livestock, and burned down some of the region's remaining original forest.
(See wildfire pictures.)
Published December 6, 2010
Footprints in the Mud
Photograph by Euzivaldo Queiroz, A Critica/Reuters
People walk the muddy bottom of the Negro River on October 26.
Many complex climate models suggest that Amazon rainfall may change little over this century, Reuters reported.
That's why scientist Rosie Fisher, of Colorado's National Center for Atmospheric Research, was shocked when she saw a map showing Amazon rainfall at less than half its annual rate so this year.
"The map that I'm looking at now looks like the extreme bit of my scenario, and it's happening right now. I'm genuinely quite alarmed by this," Fisher told Reuters.
(Do you know how climate change may affect the world's freshwater? Take a quiz.)
Published December 6, 2010
Exposed to the Elements
Photograph by Rodrigo Baleia, LatinContent/Getty Images
Raised structures sit near exposed riverbanks in Anama on October 25.
Normally, the Amazon region is awash with freshwater: 3,700 cubic miles (15,400 cubic kilometers) falls from the sky each year, the highest rate of rainfall in the world.
Published December 6, 2010
Little House on the Riverbed
Photograph by Rodrigo Baleia, LatinContent/Getty Images
A lone house stands out against a dry riverbed in Cadajas on October 25.
A prolonged drought may harm Brazil's crops. For instance, farmers in the Amazon's fertile Matto Grosso state are highly dependent on Amazon rain to grow their crops, which are extremely profitable because normally so little irrigation is needed.
Published December 6, 2010