Geophysical Institute researchers Martin Jeffries and Kim Morris began investigating the Tanana River ice break up record along with temperature data in 2004. They found links between the Nenana Ice Classic data and changes in the local and regional climate.

"The correlations we are seeing between break up on the Tanana River and Arctic climate adds to our confidence that river break up is a good indicator of climate variation," Jeffries said.

Jeffries presented his findings at the Arctic Science Conference held last week at the Westmark Hotel.

The Nenana Ice Classic began in the spring 1917 when Alaska Railroad workers surveying to build a waterfront dock bet on the exact date and time the ice on the Tanana River would break up.

Over the past 89 years, the contest has grown into an annual gaming event, the proceeds from which support local charities.

Each spring a 26 foot, five-legged tripod is built on the frozen Tanana River. A cable connects the tripod to a clock tower and when the ice moves for spring break up, the cable trips the clock indicating the exact time of spring break up.

Jeffries, a research professor at the Geophysical Institute, who has never participated in the contest, began investigating the Nenana Ice Classic as a potential indicator of Arctic climate change after reading an article in the journal Science, which highlighted the ice classic contest and a trend toward early break up dates. In the article, two California scientists discussed the possibility of a climate signal in the ice break up data.

As an Alaskan resident for 21 years, Jeffries wanted to take a closer look at the ice break up data, "to see if we can tease more climate information out of the Ice Classic."

Their research showed the Tanana River break up data matched with periods of prolonged warm or cool air. The findings prove the Nenana Ice Classic is a good proxy for climate in interior Alaska, according to the study.

The most significant determinant of variation in the ice break up data was the Fairbanks average air temperature. Overall, the ice classic data are very sensitive to large scale temp change, one factor that makes the Nenana results a good indication of climate variation and change in Alaska.

In addition to these correlations, the study identified a distinct warming pattern from the early 1960s to the present. From the historical data, Dr. Jeffries found that break up dates from 1917 through the early 1960s show no long term change; however from the early 1960s to the present, significant change occurred resulting in an average break up date 10 days earlier than in the early 1960s.

Climate signals are visible in the break up record, Jeffries said. Because the deviations in break up data match records of climate variation and change, this study could become an additional tool to identify large scale changes in climate, he said.

Changes in the climate would appear in the Nenana Ice Classic data, with break up dates responding quickly to a two to five year warming or a cooling trend.

Brooke Powers, a UAF freshman and lifelong resident of Nenana worked as a sorter for the Ice Classic in high school. Over the course of her lifetime she has noticed trends in the Ice Classic break up dates.

"I think [river break up] is really unpredictable, but overall I have notice the ice is breaking up earlier in the spring while the winters have been starting later in the fall," she said.

She added that recently the duration of the Tanana River break up seemed to be much shorter than in the 1980's and early 1990's.

Jeffries plans to continue the study, evaluating which weather and climate factors and which part of the year has the most influence over river break up.

As an educator, Jeffries uses the Nenana Ice Classic contest to teach both primary and secondary students and teachers about snow, ice and climate change.

"If you can talk about things that are relevant and unusual kids will be interested," he said.