Here’s a link to an interesting New York Times article on the effects global warming is having on the Iditarod. It includes a nice video report and slide show: http://www.nytimes.com/2013/02/06/sports/warm-weather-forces-changes-ahead-of-iditarod-race.html?smid=pl-share
The unusually warm weather is forcing officials to cancel or postpone some of the Iditarod qualifying races. To qualify for the Iditarod, mushers must complete two 300-mile races and at least one other race for a total of 750 miles.
Warmer conditions also make racing difficult for the dogs, which are used to running in colder climates.