How good a tipple of wine tastes depends on a number of different factors, from the level of tannins to how long it’s been aged, but it is also closely linked to the climate in which the grapes were grown. By looking back at grape harvests over the last 500 years, researchers have been able to delve into just how the weather has been affecting the plonk in your glass. It turns out that the wine you’re currently drinking could well be the best it’s going to get, because as climate change alters weather patterns the quality is expected to decline.

Up until now, the climate has in fact been making wine taste better. Warmer temperatures that traditionally delay rain and are followed by drought pushes forward grape maturation, meaning that they are harvested earlier in the year. This, in general, leads to a better quality and thus nicer tasting wine. By looking back at the time of harvest from regions in France and Switzerland, which have kept records from 1600 to 2007, the researchers were able to see that on average, the grape harvest is now two weeks earlier.

“There are two big points in this paper, the first is that harvest dates are getting much earlier, and all the evidence points to it being linked to climate change,” explains Elizabeth Wolkovich who coauthored the paper published in Nature Climate Change. “Especially since 1980, when we see a major turning point for temperatures in the northern hemisphere, we see harvest dates across France getting earlier and earlier.” This has driven a significant increase in the quality, meaning that current batches are pretty good.

^{Wine harvested earlier in the year is normally better quality, but this might change. David Rebata/Shutterstock}

But this is where things start to uncouple. Whereas before the pre-industrial era, high temperatures were linked with a following drought that traditionally acted as a predictor of an early harvest and thus to better tasting wine, this relationship no longer holds. With climate change, temperatures in general are getting warmer, but they are now not necessarily followed by this dry period, and can now be shadowed instead by rain that has the reverse effect – decreasing a vintage's quality.

“The bad news is that if we keep warming the globe we will reach a tipping point,” says Wolkovich. “The trend, in general, is that earlier harvests lead to higher-quality wine, but you can connect the dots here...we have several data points that tell us there is a threshold we will probably cross in the future where higher temperatures will not produce higher quality.” And it’s not just one grape type that will be feeling the heat. The study looked across the board, from Burgundy, to Bordeaux, to Loire.

This means that wine growers should either shift to growing a more heat tolerant variety of grape, or potentially shift their activities north or south, depending on the hemisphere in which they already are in, to follow the ideal temperatures and weather patterns.