A press release on a new paper on global warming associated with ozone levels in the atmosphere appeared on Phys Org but the effect was slight so I didn't take the bait or mention the link – see http://phys.org/print295191415.html but then yesterday Tall Bloke and Anthony Watts posted on the subject – see http://tallbloke.wordpress.com/2013/08/08/surprised-scientists-find-ozon…
The gist is that lower ozone levels at the Poles were thought to cause cooling – but scientists at Columbia University in New York have found a small warming effect – which may turn out to be a little more than slightly so after the surprise has died down. A dceptic might just poke out his tongue – well, the ozone is dispersed by the solar wind so why wouldn't it warm rather than cool? However, reservations are in order – computer modelling is at the heart of the study (not actual observation).