There was an Horizon programme on this last year, it's called Global Dimming.
Because we have been pumping tons of particulates into the atmosphere for more than a century it is actually masking the effects of greenhouse gases, now that we are not pumping so much crud up there it is thought the effects of greenhouse gases are much worse than was originally thought.
We may have reduced particulates but have increased CO2 emissions.
So everyone, light a bonfire!
