The atmosphere today, she said, has 33 percent more carbon dioxide than it did in 1850. Carbon dioxide is the most common "greenhouse gas" — blamed for trapping heat and raising the earth's average temperature by 1 degree Fahrenheit over the past century. That temperature rise has been uneven around the world, she said, with parts of Alaska now 5 degrees warmer than they were 100 years ago.

Begich said he has seen the effects: The popular tourist destination of Portage Glacier, which is inside the Anchorage city limits, has melted so that it is almost undetectable. Forests in Alaska are being destroyed by infestations of spruce-bark beetles, bugs that until recently couldn't survive in Anchorage's cold climate.

Bierbaum said if emissions continue as they are, we face "a roasted world," with possibly quadrupled carbon-dioxide levels one day that will send temperatures skyrocketing.

The Sundance Summit kicked off Sunday evening with a speech by former Secretary of State Madeline Albright. It continues today with speeches by Begich and former Sen. Gary Hart, D-Colo., among others.

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