Democratic rivals put climate change firmly on the agenda

Four of the five contenders call for action on the issue despite its relegation to a single question in the final part of the CNN event

Democratic contenders promised repeatedly to take forceful action against climate change in their first presidential debate on Tuesday night - even before they were asked.

Much to the disappointment of campaigners, CNN allocated just one question to climate change, outsourced to a member of the public, and relegated to the final segment of the two-hour encounter.