This year's ozone hole over Antarctica is bigger and deeper than any other on record, U.S. scientists reported on Thursday. .... Concentrations of ozone-depleting chemicals in the lower atmosphere have been declining since 1995,It is undisputed that the banned chemicals deplete ozone. What was never settled, and is still debated in science journals, is whether their effect was significant or insignificant. It was found that the chemical effects were insignificant based on usual gas phase reaction chemistry. It was then proposed that maybe there were catalysts which greatly magnified what would have been an otherwise small effect. This question may not be settled for decades.
Global warming is similar. CO2 is indisputedly a global warming gas but, by itself, it is quite minor. It only becomes important if there is a feedback mechanism whereby changes in CO2 cause changes in atmospheric H2O which magnify the effect. The scientific uncertainty in this feedback mechanism is a key reason why even global warming advocates cannot settle on a number for how much warming will happen.
Unfortunately, uncertainty is unacceptable to political activists who always must claim to have absolute answers and have no qualms about using their received wisdom to rearrange the lives of the rest of us.
UPDATE: NASA attributes part of ozone hole increase to "colder than average temperatures."