Wine - CO2 producer or not?

This months Green theme has got me thinking about wine and CO2.

We know the process of fermentation produces CO2, but the vineyards that produced the grapes that are fermented take CO2 from the atmosphere by photosynthesis.

So does fermentation just return an equal amount of CO2 to that captured by photosynthesis?

All of the carbon present in the grapes was captured from the atmosphere by the vine. Fermentation releases some of that back into the atmosphere. So just looking at the growth of the vines and the fermentation, it's a net reduction in atmospheric CO2. Of course this is ignoring all of the other energy-consuming aspects of winemaking.

-Paul W.