PBS: JUDY WOODRUFF: Finally tonight, new indications that the planet is warming, especially in the frozen north. Scientists have been tracking Arctic thawing for decades, and they have seen a dramatic increase since 2000.
When holes opened up in the earth recently in Siberia, a wave of speculation was set off as to their cause. Scientists now think warming is the culprit.
To help us understand all this, we welcome back Tom Wagner. He directs studies of the polar regions for NASA.
And it`s good...