Weather wager. In late April residents of Nenana, Alaska, put a wooden tripod on the ice (top) and place bets on when it will fall into the river (bottom). The annual lottery has now revealed evidence of global warming.

Ice Lottery's Scientific Payoff

Without knowing it, residents of Nenana, Alaska, have been betting on global warming for decades. Each spring, the townspeople erect a wooden tripod on a nearby river and take wagers on when it will fall through the ice. This lottery has inadvertently accumulated almost a century of data on the river's thaw, and a recent analysis of town records shows that the ice cracks about 5 days earlier than it used to. Researchers hope their findings, which match other climate change records, will encourage others to seek climate data in unlikely places.

In 1917, a group of railroad employees working on the Tanana River in central Alaska gathered $800 in wagers on the exact minute that the ice would begin to give way. The friendly bet became an annual tradition in the nearby town of Nenana, and it has since grown into a statewide phenomenon. Today, Alaskans come from all over to partake in the Nenana Ice Classic, enjoying a banana-eating contest and betting on a jackpot that exceeds $300,000.

Raphael "Rafe" Sagarin, an ecologist at Stanford University, believes this betting tradition has created an extremely accurate record of local climate change. Because of the high stakes, he says, organizers have tried to use the same location, equipment, and definition of what constitutes the "breakup" for 84 consecutive years. When he and his colleague Florenza Micheli analyzed records from the Ice Classic, they found that the ice now breaks an average of 5.5 days earlier than it did in 1917. The same warming trend exists in regional temperature readings. Sagarin hopes that the results, appearing in the 26 October issue of Science, will encourage others to look for environmental responses to global warming in data sets collected informally by individuals or communities, like a bird-watcher's records.

"I think it's cool that people living their ordinary lives can contribute to the scientific community," says Julie Coghill, the Ice Classic's Web master, who lives in Fairbanks, Alaska, and has attended the event for decades. Is she concerned that Sagarin might use his data to purloin next year's prize? "Absolutely not," she says. "Rafe is welcome to buy as many tickets as he likes."

Related sites

The Ice Classic Web site
A Virtual Visit to Nenana
An overview of ways to reconstruct paleoclimate, from Science