Whatever happened to the idea of geoengineering the planet?

Geoengineering is the deliberate manipulation of nature to lessen or reverse the impacts of global warming. Even its supporters concede it’s risky. A decade ago, the controversial technology was talked about as a “necessary evil” in the fight against climate change – a matter of when, not if. However, despite the continued heating of the planet, no large scale testing has yet been attempted. In this program we ask why? And where to from here?