Originally Posted by JimTheHick
Esters contain two atoms of oxygen, so doing an open fermentation and also maximizing the surface area of the wort to atmospheric oxygen with a very wide vessel would encourage ester formation by allowing plenty of oxygen to be present. CO2 is a terminal product, its oxygen can't be used to create esters. This all makes perfect sense.
I'm not so sure about this, it may be more of a negative feedback response from the carbon dioxide in the finishing beer pressuring the yeast to stop whatever metabolic pathway produces the esters in the first place. Esters form from a carboxylic acid and an alcohol undergoing a condensation reaction. The oxygen itself in the beer/wort wouldn't really be responsible at all for this unless the yeast are fixing the oxygen in some sort of carboxylic acid cycle. I'll look into that and see what we come up with!