LULU GARCIA-NAVARRO, HOST:
With the advent of spring, Alaska's winter-frozen rivers are breaking up. After nearly six months of solid ice, water is starting to flow again. One river, though, that's still frozen is an hour south of Fairbanks. As Dan Bross of member station KUAC reports, it's the site of a contest that provides a unique record of climate change.
DAN BROSS, BYLINE: Buy a ticket in the Nenana Ice Classic, and you could win $300,000. All you have to do is guess when the ice on the Tanana River will break up. Regular ice measurements fuel anticipation every spring.
JOSH RIDGEWAY: Yeah, it's actually been kind of a fun project coming out here and drilling the holes for them. Get out here in the morning when the sun's coming up and play.
BROSS: Josh Ridgeway and his brother Judah are charged with drilling and measuring ice thickness.
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BROSS: Here on the Tanana River in the tiny city of Nenana, the ice has gone out as early as April 20 and as late as May 20.
JOSH RIDGEWAY: Wee. Thicker than I figured it would be.
BROSS: On this day, it's over 3-feet-thick, far from ready to break up. Ice Classic records date back to 1917, valuable data to National Weather Service climatologist Rick Thoman.
RICK THOMAN: Not just 100 years of dates - but it's been gathered in that same way for almost all of that time so very consistent.
BROSS: Thoman points to a gradual trend toward the river flowing ice-free earlier.
THOMAN: What's now an average breakup date, about April 30 - in the early part of the 20th century, that would have been an unusually early breakup date.
DENNIS ARGALL: The climate's always changing. It's going to keep changing.
BROSS: Dennis Argall has been involved in the Nenana Ice Classic for 50 years. He's sitting at a 1980s vintage computer terminal inside Ice Classic headquarters. Argall is skeptical about human-driven warming.
ARGALL: I don't believe in the global warming stuff.
BROSS: That's in part because he witnessed the second latest breakup on record just a few years ago.
ARGALL: I think humans would think a whole lot of themselves if they think they could affect the globe. You know, it's a big world.
BROSS: That's a sentiment that contradicts widespread scientific consensus, but it's a belief common among some Alaskans. Back on the Tanana River, ice drillers Josh and Judah Ridgway put it this way.
JOSH RIDGEWAY: I think there's a cycle, but I don't know what man's role is in it.
JUDAH RIDGEWAY: Yeah, climate change happens, but I don't think it's man-caused...
JOSH RIDGEWAY: It might be...
JUDAH RIDGEWAY: ...In my opinion.
JOSH RIDGEWAY: ...Man-contributed. But if we don't start behaving, this planet's going to shake us off of it...
JUDAH RIDGEWAY: (Unintelligible).
JOSH RIDGEWAY: ...One way or the other (laughter).
BROSS: The Ridgeway brothers' ice-measuring job is done for this season. As of now, the melting ice is getting too risky to walk out on. That means Alaskans will soon know who wins this year's jackpot and that summer is on the way. For NPR News, I'm Dan Bross in Nenana, Alaska.
(SOUNDBITE OF POPPY ACKROYD'S "ALIQUOT")
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