STEVE INSKEEP, host:
A canal that changed the world is now having to change itself. The Panama Canal revolutionized shipping between the Atlantic and Pacific Oceans. This morning it's the focus of Climate Connections, our year-long series with National Geographic, because it could be affected by global warming. We have more, this morning, from NPR's Jon Hamilton.
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JON HAMILTON: If you've ever bought shoes at Wal-Mart or bananas at Costco, there's a good chance they came through the Panama Canal on a cargo ship like the Maersk Dartford.
Mr. JORGE DE LA GUARDIA (Panama Canal Authority): We're looking at a Panama ship. It's going south.
HAMILTON: Jorge de la Guardia works for the Panama Canal authority. We're watching the Dartford squeeze through the Miraflores locks on her way from the Atlantic Ocean to the Pacific. Like thousands of ships around the world, the Dartford was built to what's become known as the Panamax standard, that's the maximum size that can still navigate the Panama Canal.
Mr. DE LA GUARDIA: Panama ship is defined as a ship of over 100 feet in the beam and they usually are from about 850 to 965 feet in length.
HAMILTON: The gap between the Dartford's steel hull and the lock's concrete wall is two feet. It's such a tight fit that pilots often use full power to force a ship into the lock like a cork into a wine bottle.
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HAMILTON: Right now about four percent of all world trade passes through the Panama Canal. It's the short cut between the Atlantic and the Pacific. De la Guardia says Panamax ships like the Dartford pay about $250,000 for each crossing.
Mr. DE LA GUARDIA: Well, you know, the canal is the most important industry that Panama has. Because of the canal we have ports. The port activity is increasing tremendously.
HAMILTON: Ships pay to use the canal because the alternative is a 9000 mile detour around Cape Horn on the southern tip of South America. The only other route is way north through the Arctic, and so far ice has made that a risky option. The need for a global shortcut was why a French company started building the Panama Canal at the end of the 19th century. The U.S. finished it in 1914. The canal is critical to international trade, especially between the U.S. and China.
But there's a problem. International shipping companies are starting to use bigger ships because they're more efficient, and these new vessels are too big for the canal. So Panama is spending more than $5 billion on an expansion project. It includes a new set of locks that are much wider and deeper than the existing two sets. The project got underway officially last year.
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HAMILTON: The expansion should be done by the canal's 100th birthday in 2014. That will solve the problem of accommodating bigger ships, but it's also creating a new problem: the canal depends on rain and that's where climate change comes in. The Panama Canal isn't just a channel between two oceans. In fact, it doesn't use ocean water. It runs on fresh water pouring in from 17 artificial interconnected lakes.
Mr. DE LA GUARDIA: Everything works by gravity.
HAMILTON: Jorge de la Guardia says the water flows down into a series of locks, or lanes, as they're sometimes called here. These locks gradually raise each ship 85 feet above sea level. De la Guardia says that takes a lot of water.
Mr. DE LA GUARDIA: Yeah, a transiter, a full transiter going from the Pacific or the Atlantic Oceans, from ocean to ocean will take about 55 million gallons of fresh water.
HAMILTON: And it's your job to make sure there's enough water to keep the ships moving?
Mr. DE LA GUARDIA: Yes, yes.
HAMILTON: The Panama Canal already consumes three times as much water in a day as the city of Los Angeles. When the new lane for big ships is built, the canal will need even more. The question is, will there be enough? Stanley Heckadon-Moreno works at the Smithsonian Tropical Research Institute in Panama City. He says the lakes that feed the canal are vulnerable to the climate fluctuation known as el Nino.
Mr. STANLEY HECKADON-MORENO (Smithsonian Tropical Research Institute): What if the theory of global warming were to increase the number of el Nino events which will bring greater and more devastating droughts to the isthmus and water will become definitely scarcer for the canal.
HAMILTON: El Ninos in 1997 and 1998 left the canal so short of water that ships had to unload part of their cargo to keep from running aground. It was the worst drought in the canals history and it disrupted shipping around the world. No one really knows whether climate change is going to make el Ninos more frequent, but Heckadon sees some ominous trends.
Mr. HECKADON-MORENO: Inside the canal watershed, inside the valley of the Chagres river, there has been an affect on that micro watershed, and there has been a decrease in rainfall.
HAMILTON: So far, that's probably got more to do with the huge number of trees cut down than with climate change. But the result is the same, and officials are worried. Carlos Vargas from the Canal Authority says the expansion plan allows for some climate variability.
Mr. CARLOS VARGAS (Panama Canal Authority, Manager, Meteorological and Hydrographic Branch): It is very important because we all know that the canal depends on water. If it doesn't rain we don't have enough water for the operation of the canal, so we have to take it very seriously.
HAMILTON: The plan calls for storing more water in lakes, and perhaps using less water to generate electric power. And the most important hedge against a water shortage is the new locks themselves. The ones in the lane for big ships will use a design that recycles 60 percent of the water.
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HAMILTON: Even so, Jorge de la Guardia from the Canal Authority says that if el Nino years come more frequently, the canal could still be in trouble. Solutions, like creating new lakes would cost a lot and destroy even more of the dwindling rain forest. But de la Guardia says Panamanians will probably do whatever it takes to keep water flowing to the canal.
Mr. DE LA GUARDIA: What I would love to see is that we make such good business with a third lane, that we make a fourth lane and then we'll need water, right away.
HAMILTON: Drought is just one way that climate change looms over the future of the Panama Canal. Rising seas could flood ports along the shipping routes that go through the canal. Extreme weather is another threat. When Hurricane Katrina delayed ships on the Mississippi River, they missed their slots to go through the canal. It created a huge traffic jam. And then there's that melting ice in the Arctic. It could make the Northern Passage a viable option for shipping. If the world gets warm enough, goods headed for the U.S. may skip Panama all together.
Jon Hamilton, NPR News.
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INSKEEP: You can hear more stories in this series at npr.org/climateconnections, which is where you can also see videos of climate science in action. That's from public television's Wild Chronicles.
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