The general public have not yet heard of geoengineering or climate engineering. It is the grandest of all ideas for if all other ideas for solutions to climate change fail - ideas for a deliberate large-scale intervention in the Earth's climate system with the aim of reducing global warming by reversing or slowing it.
The Intergovernmental Panel on Climate Change (IPCC) released last Friday the most comprehensive ever study on global warming. The landmark report, prepared by more than 200 scientists over two years, concludes that global temperatures could rise by up to 4.8 Celsius (8.6 Fahrenheit) by the end of this century compared to pre-industrial levels, but could potentially still be held to 0.3 C (0.5 F) with deep, speedy cuts in emissions.
The truth is that Tory sceptics have been emboldened by a disturbing change in tone from their frontbench since David Cameron entered Downing Street. The administration he promised would be the "greenest government ever" now boasts an Environment Secretary who doesn't believe in climate change, an Energy Minister who has described climate change as a matter of "theology" and a Chancellor peddling a perverse false choice that we cannot combat global warming without "putting our country out of business."
Rejected and ridiculed by the rest of us, conspiracy theorists tend to hide away on internet chat forums where they blather on about the collapse of 7 World Trade Center, the rise of the Illuminati or the omnipresence of Mossad. Not the climate-change deniers. Unlike Israel's intelligence agency, they really do seem to be omnipresent these days.
Climate change is still happening. There is more certainty than ever that human greenhouse emissions are the main driver of this change. Climate change is a huge threat to people, species, habitats and the places we care about. In a nutshell, that the risks posed by a changing climate are deeply concerning.