The U.N. chief ratcheted up his warning about climate change and said the world's thirst for fossil fuels is a "Frankenstein monster" that spares no one, while calling for greater attention to risks posed by artificial intelligence if its ascent goes ungoverned.

António Guterres, the United Nations secretary-general, headlined a flurry of activities and talk sessions on Wednesday as the World Economic Forum's annual meeting in Davos.