Why has geoengineering been legitimised by the IPCC?

Jack Stilgoe in the Guardian (UK): Today marked an important punctuation mark in the story of humanity's attempts to get to grips with climate change as the Intergovernmental Panel on Climate Change (IPCC) published its summary for policymakers (pdf here). Climate sceptic journalists and interest groups will be making the most of the tiniest surprises and variations in the climate scientists' new representation of the state of their art. But the evidence is largely unsurprising. For all the talk of a "hiatus" in warming, the IPCC continues to fly its one major fact: more greenhouse gases means more warming.

The big surprise comes in the final paragraph, with a mention of geoengineering. In the scientific world, a final paragraph is often the place to put caveats and suggestions for further research. In the political world, a final paragraph is a coda, a big finish, the place for a triumphant, standing-ovation-inducing summary. The IPCC tries to straddle both worlds. The addition of the word "geoengineering" to the most important report on climate change for six years counts as a big surprise.

There are many reasons to be worried about geoengineering. The idea is old. Countless inventions have been proposed as a technological fix to climate change, but scientists have only recently taken it seriously. Their previous reticence was largely due to a concern that talking about easy solutions would wobble the consensus on the need for a cut in emissions that had been painstakingly built over decades. Geoengineering was taboo – too seductive, too dangerous and too uncertain. It is now moving towards the mainstream of climate science. As the number of geoengineering studies published shoots up, it is now acceptable to discuss it in polite scientific company.

There is an argument that the taboo has already been broken and that, like sex education, it therefore has to be discussed. Those of us interested in geoengineering were expecting it to appear in one or two of the main reports when they are published in the coming months. To bring it up front is to give it premature legitimacy....