This carbonated style of wine is either intentionally added by the vintner or occurs as a by-product of post-bottling fermentation. Bottling at cold temperatures is another way that carbonation can be captured in the bottle.

If there is a distinct sulfur/sauerkraut/swamp smell, accompanied by cloudiness and sediment, then wine is considered flawed; this is the result of dead yeast cells that have also decayed in-bottle under anaerobic conditions.

See, “Petillant“.