She believes that ozone responds to changes in solar UV, but said the picture was complex. In the upper stratosphere, about 50 km up, an increase in ozone will have a cooling effect. But about 20 km above the Earth, more ozone will act like other greenhouse gases, trapping IR radiation and enhancing warming. I think it's very unlikely anyway that the response of ozone to solar UV will be as dramatic as some reports have claimed. Dr Mike Hulme, executive director of the Tyndall Centre for Climate Change Research at the University of East Anglia, UK, said the so far unquantifiable contribution of the Sun is consistent with climatologists' understanding of what is happening.
Most scientists say it is fairly guarded, and is supportable.
It allows both a substantial role for the Sun, and an inconsequential one. It is this range of uncertainties that makes future predictions so difficult.