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PRI's Environmental News Magazine

Brazilian Drought

Air Date: Week of October 21, 2005

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The Brazilian province of Amazonas has declared a state of emergency to contend with what appears to be the severest drought in the Amazon in recorded history. The drought has worldwide implications as the Amazon River makes up nearly twenty percent of the freshwater on the Earth's surface. Scientists aren't completely sure why this is happening, but the effects of the drought are both undeniable and far-reaching. Host Steve Curwood talks with Dr. Dan Nepstad, a senior scientist from the Woods Hole Research Institute who's based in the Amazon.

Transcript

CURWOOD: From the Jennifer and Ted Stanley Studios in Somerville, Massachusetts, this is Living on Earth. I'm Steve Curwood.

Brazilian officials have declared a state of emergency to deal with what may turn out to be the severest drought on record in the Amazon. The drought has worldwide implications, as the Amazon River makes up nearly twenty percent of the freshwater on the Earth's surface, and carries more water than the nine other largest rivers of the world combined. But right now, with rainfall running at half of normal levels, the Amazon is at an all-time low.

Scientists aren't completely sure why this is happening, but the effects of the drought are undeniable and far-reaching. Fish are dying, wildfires have been intense, and people who live along the riverbanks may be losing a way of life that dates back for centuries. Joining me now is Dan Nepstad. He's a senior scientist at the Woods Hole Research Center and is based in Brazil. Hello, sir.

NEPSTAD: Hi, Steve.

CURWOOD: Can you describe for us, Dan, what you’re seeing down there right now?

NEPSTAD: I’m here at the lower end of the Amazon, right at the mouth, and the rivers I’ve seen at this end are quite large and they’re amazingly dry. Some rivers where you normally have to take a boat across, you basically walk ankle to calf deep in water, and there’s extensive mudflats where normally there would be clear water. A lot of these mudflats are getting covered with dead animals, especially further up the river.

CURWOOD: Dead animals?

NEPSTAD: Dead fish, in some places dead dolphins, dead manatees. We’re still not sure why a lot of the animals are dying. With the fish, it’s probably a lack of oxygen as the rivers shrink in size and fish actually get stuck in some isolated ponds that run out of oxygen.

CURWOOD: Talk to me about the humanitarian side here. The people that live in this region of Brazil, of course, depend on the river system for survival. What’s it like in the villages there along the rivers that rely on the Amazon for transportation?

NEPSTAD: We’re seeing families and small communities of riverside dwellers getting cut off from society as their means of transportation, the river network, dries up so their small boats can’t get through. They’re running out of water because of the problem of animals dying, and their water supply from the river is contaminated by dying and decaying animals.

CURWOOD: What sort of issues do you see arising in the recovery process for them after a drought, after an event like this?

NEPSTAD: I think, in addition to the large number of animals dying, there’s a lot of other problems that are coming down the pike. Most cities, most little towns in the Amazon, don’t have any sewage treatment. Their sewage treatment is to put a pipe into the river. When you reduce the flow of these rivers, your former solution of dilution stops working and we’ve got cesspools building up around these little towns. That has got all of the makings for disease, intestinal disease, cholera, that sort of thing.

Water that’s not moving is also a wonderful breeding ground for insects, including mosquitoes, that carry things like malaria, that carry dengue, and other diseases.

CURWOOD: Talk to me about the theories that are being thrown around as to why the drought is so bad this year. I mean, I’ve heard that it might be deforestation, then I hear that maybe it’s the rising temperatures in the Atlantic Ocean, and, then again, folks say it’s part of the normal cycle. Why do you think the Amazon is in crisis right now?

NEPSTAD: The best single explanation for this year’s record drought is the heating of the oceans off the coast of Africa, the Atlantic Ocean. That heating started spreading over the Gulf of Mexico, providing a tremendous source of hot, damp air that, of course, started to rise, and that air is descending over the western Amazon. And that’s a typical pattern for the dry season for the Amazon, but the heating of the surface waters of the Atlantic reinforced the typical pattern. So there’s all this air descending over the Amazon, drying it up in the process.

Deforestation also inhibits rainfall events. Perhaps it’s linked to the heating of the Atlantic Ocean. It could be that the heating of the Atlantic Ocean is also at play in the large number of hurricanes we’re seeing this year. So, ironically, the Amazon’s drought and fire and the misery that’s taking place where I am now, and the misery that’s taking place in New Orleans, may have a common link.

CURWOOD: Tell me about the fires. With the drought, and the death of the fish and the other animals, I understand there are a lot fires. How extensive are they?

NEPSTAD: We’re trying to get a handle on how big the area that burned is. Right now, it looks like it’s about half the size of Connecticut. Most years Amazon forests are amazingly resistant to fire; they’ve got root systems that go down the equivalent of a five-story building into the soil so that during droughts they can keep their green, dense leaf canopies which makes them very difficult to burn.

What’s happening this year, though, is they’re running out of water. There’s just not enough water in the soil. And what that means is that there’s a potential for a vicious feedback in which drought leads to tree death, which increases the risk of fire, which increases the chance that drought will be more severe in the future, which increases again the risk of more tree deaths.

CURWOOD: I know you’re a scientist but how do you feel about all of this? You’ve been working there for years.

NEPSTAD: Yeah, I’ve been working in the Amazon for the last 21 years, and I’ve never seen such potential for the whole system to become degraded as I’ve seen this year. And I think what’s surprising to me is how precarious many of the traditional populations that live along the rivers throughout the region, how precarious their existence is in the face of a warming planet and drought such as this.

CURWOOD: Dan Nepstad is senior scientist for the Woods Hole Research Center and a forest ecologist in the Amazon. Thank you, sir.

NEPSTAD: Thank you.

 

 

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