Alcohol levels in wine have been steadily creeping up over the last 30 or so years. For some this means more bang for your buck, for others the 12.5% - 13.5% 1980’s standard is sorely missed. The good news though is that the rise has largely resulted in better wines, if a bit stronger.
Climate change has played a small part (hotter weather = riper, more sugary grapes = a higher alcohol wine once all the sugar has been fermented), but the main reason is the modern trend of delaying the harvest until the grapes have reached ‘phenolic ripeness’.
This means hanging on until the tannins, colour and flavour of the grape have reached optimum levels, rather than just harvesting when the sugar level is correct. This extra time on the vine inevitably leads to more sugar, and therefore more alcohol. The payoff though is that the wine will have softer tannins, deeper colour and more intense flavour.
Although this extra alcohol will obviously give the wine a bit more clout, it shouldn’t be particularly noticeable to the taste. Well-made wine is all about balance and a good wine maker will make sure that the alcohol is in balance with the other elements of the wine. It is quite possible for a badly made, unbalanced wine to taste too alcoholic even if it only clocks up 11% abv.