U.S. Secretary of State John Kerry says climate change is as dangerous as, if not more than, the threat from the Islamic State and other extremist groups.

Speaking on Friday at an international conference on climate change, Kerry said the issue might not get as much public attention as terrorism.

But he says the climate change meeting is as important as one in Washington this week on combating the Islamic State group. He says what's being discussed in Vienna could "literally" save life on planet Earth.

Kerry was making a brief appearance at the conference of parties to the Montreal Protocol, a 1987 global treaty to phase out many chlorofluorocarbons from aerosols and refrigerants that deplete the ozone layer.