Obama: Climate change is 'greatest threat'

US President Barack Obama has unveiled his Clean Power Plan - his strategy to cut greenhouse gas emissions from US power stations by nearly a third by 2030.

Outlining the details, Mr Obama said that "no challenge poses a greater threat to our future and future generations than a change in climate".

The president warned that this was "the first generation to feel the impact of climate change and the last generation that can do something about it."