Summer hasn't even arrived yet fire restrictions have been put into place at Kings Canyon and Sequoia national parks in California.

Somewhere in the ten miles from the visitor center at Mississippi National River and Recreation Area in St. Paul, Minnesota, across the river to Minneapolis, I crossed an invisible line. It would have risen like a wall of ice, perhaps a mile high, just 15,000 years ago – a line demarcating the extent of the last glaciation.

Two climbers, exhausted and battling hypothermia, remained stuck Thursday high on Denali where they were awaiting rescue in a "crude snow cave." Climbing rangers from Denali National Park were awaiting a break in the weather at a high camp at 17,200 feet on the 20,310-foot mountain, roughly 2,400 feet below the stranded climbers.

Two climbers were stranded Wednesday high on Denali by frostbite and hypothermia, while another member of their team who had managed to descend part of the way from the 20,310-foot summit was rescued.