Transcript

TAMSIN EDWARDS:

It's difficult to know what kind of field experiments we're going to see for geoengineering over the next few years, because, of course, people are quite careful in planning them out in regulation and public opinion.

But the three that were described in most detail by Keith and others in 2014, first of all, were sulphate aerosol particle injection at 20 kilometres. So that plan was to see what effect the particles would have on the ozone layer. That proposed experiment is called SCoPEx -- for stratospheric controlled perturbation experiment.

The second is Marine Cloud Brightening. So putting salt particles into the air to see the effect on clouds. And people have proposed using a scaled up version of part of the E-PEACE experiment for that. And the third is reducing the lifetime and the thickness of cirrus clouds by injecting bismuth triiodide into the clouds to turn water into ice particles. And that reduces their lifetime and their thickness.

But, as I say, these are the most detailed proposals, but we don't know what kind of timeline they might be carried out - if at all - so I think watch this space.