temperatures have hit -14 in parts of the balkans, the coldest in more than 50 years. and in greece, medical officials warned of "inhuman" conditions at migrant camps. meanwhile, in northern california, rescue crews used boats to reach stranded people after the heaviest rain in a decade. thousands more have been urged to evacuate ahead of the floods. >> inskeep: and on wall street, oil prices went up and so did stocks. for weeks now, people have been waiting for the dow to climb over 20,000-- it hasn't quite happened yet. the dow jones industrial average gained 98 points to close at 19,954. the nasdaq rose 11 points, and the s&p 500 added six. >> inskeep: and finally tonight, we continue our series about "the obama years." in his farewell address last night, the president spoke of his actions against climate change, including a global accord to reduce emissions. he did more as his time in office went on, despite opponents who criticized the costs, or doubted the science. miles o'brien reports, as part of our weekly look at the "leading edge" of science and technology.