what could be clearer?

Meanwhile an 84-year-old betting contest held annually on a frozen Alaskan river is providing the latest evidence of a global thaw. The Nenana Ice Classic has been held since 1917 on the Tenana River.

Contestants bet for a jackpot, that this year hit $300,000, on the exact moment when a wooden tripod erected on the frozen river falls through the breaking ice each spring. When they checked the records they found that the breakthrough occurs today an average of five days earlier than at the start of the contest.
indiaresource.org 15 Mar 2002