Reuters: A U.N. advisory group agreed on Tuesday it would be tough but feasible for rich nations to raise a planned $100 billion a year from 2020 to help poor countries combat climate change, Norway’s Prime Minister told Reuters. Jens Stoltenberg, who co-chaired a final meeting of top experts in Addis Ababa on Tuesday with Ethiopian Prime Minister Meles Zenawi, said higher penalties on carbon emissions had to be a main source to raise the cash. “We have concluded that it is challenging …