The UN's Environment Programme (UNEP) is warning that crunch time for the planet is now a reality, and that any time left for climate delays has already run out. It warns that extreme heatwaves, storms, droughts and floods are already ravaging communities, this with global temperatures rising less than 1.5°C above pre-industrial levels to date. The UNEP says that what is now needed is political courage to end the world's fossil fuel addiction. In Perspective, we spoke to the director of the UN Environment Programme's Copenhagen Climate Centre, John Christensen.