BBC: The costs of inaction on climate change will be "catastrophic", according to US Secretary of State John Kerry.
Mr Kerry was responding to a major report by the UN which described the impacts of global warming as "severe, pervasive and irreversible".
He said dramatic and swift action was required to tackle the threats posed by a rapidly changing climate.
Our health, homes, food and safety are all likely to be threatened by rising temperatures, the report says.
Scientists and officials...