Ozone back in the equation?

I understood that the ozone layer being destroyed by CFCs problem had been sorted out, and that the holes were now contracting. But it now seems that ozone has yet another trick up its sleeve, this time to do with accelerating global temperatures. Full article is on the RSC - Chemistry World.

"Ozone was already known to have a significant direct greenhouse gas (GHG) action. But the new effect is an indirect one, resulting from the toxic effect of high ozone levels on land plants."

Apparently, ozone in the lower atmosphere directly affects the way that plants absorb CO2, reducing the land carbon sink capability.

"Land plants absorb CO₂ through pores in their leaves called stomata. When atmospheric ozone levels reach about 40ppm - already reached in many parts of the world - these stomata contract, reducing the plants' CO₂ uptake. Moreover, ozone levels are expected to reach 70ppm in many parts of the world by the year 2100. This will suppress the land carbon sink, push up the equilibrium level of atmospheric CO₂, and boost the greenhouse effect"

This "could boost average world temperatures by a further 0.5-1.25°C - compared with the 2-5°C that will result from a doubling of atmospheric CO₂."

This appears to suggest that things could get even worse than predicted; but no doubt there will be some counter argument that suggests that this is all a load of guff too!

Is it just one more straw on the camel's back to worry about?

ADDENDUM 1 (from Junkk Male):

Real Climate: Ozone impacts on climate change
The Ecologist: Rising ozone levels could stunt plant growth