The tough issue is the glass bottle.
Vines are perennial crops and therefore do a great job capturing CO2 from the atmosphere (sequestration is the correct biological term). The estimate is that each hectare of vines can capture approximately 2.8 tonnes of CO2. So far so good.
In the UK we can assume a hectare of vines produces on average 6.5 tonnes of grapes which would make approximately 4,225 L of wine (in some years and some vines this may be a lot more or a lot less). To put this all into bottle requires 5,633 x 75cl bottles.
Unfortunately, the bottles required to make Traditional Method sparkling wine are hefty, weighing in at around 835g/bottle to enable the glass to withstand the pressure of the sparkling wine within the bottle. The carbon emissions to produce 5,633 sparkling wine bottles are 6.77 tonnes CO2.
A big gap to find ways of off-setting. Things look a little better when we look at still wine, where the bottles weigh around 400g/bottle and so the carbon emissions are less than half at 3.24 tonnes of CO2 for 5,633 bottles.
We are looking at every area of our business to find ways of reducing our carbon emissions and increasing our carbon sequestration to help off-set the glass bottle use. Finding the answer on what to do about glass bottles is the most difficult issue. Re-use (as opposed to re-cycling) would seem the obvious answer if we could create a system to make it work or moving away from glass bottles for wine? Will everyone be happy to move to alternative packaging? How will we make this work for sparkling wine? As always, delving into the reality of carbon costs brings up lots of complex issues but is the only way to really start addressing the problem.