Warming climate is messing with French wine

Things are getting hotter in France's famous wine-growing regions.

Bordeaux, Burgundy, Champagne, and other regions in France and Switzerland that are known for wine, are warming up. The heat is affecting the way grapes are grown and harvested in ways not seen at any other time in the last 400 years, according to new research.

A man harvests the wine grapes on September 21, 2015 at the Muscadet vineyards of the Cognettes domain, in Clisson, near Nantes, western France.
Jean-Sebastian Evrard | Getty Images
A man harvests the wine grapes on September 21, 2015 at the Muscadet vineyards of the Cognettes domain, in Clisson, near Nantes, western France.

So far, the hotter temperatures may be producing better fruit, and better wine, at least some of the time. But if the air around the vineyards continues to heat up, it could pose some significant challenges for regions that have been growing grapes for centuries.

France's wine regions are relatively cool, compared with those found in places such as California and Australia, and there is a particular seasonal pattern that seems to produce the ideal grape.

The best grapes are thought to be grown in years when there are heavy rains early in the season, followed by a dry, hot summer with a seasonal drought.

The rain in spring and early summer fuels plant growth, while the dry conditions later on push the plants to focus more on producing fruit, according to a study published online Monday in the journal Nature Climate Change.

The drought has historically been crucial to achieving the temperatures necessary for the best grapes.

Indeed, there is a solid correlation between early harvests and high-quality wines, with the best wines often being those from when the temperatures are so high the grapes are harvested early.

Since 1981, the average temperatures have been rising to the point that the late-season drought is no longer necessary to achieve the ideal temperature for harvesting.

Over the last few decades, the average harvesting date has crept up an average of about 10 days, according to lead author Benjamin Cook, a climate scientist at Columbia University's Lamont-Doherty Earth Observatory and NASA's Goddard Institute for Space Studies.

This has brought many years with highly rated wines, Cook told CNBC.

"But there is likely to be an upper threshold" for that correlation between high temperatures and quality grapes, Cook said. "Past a certain point, you are no longer getting a benefit from higher temperatures, and you may even see a deterioration in quality."

In 2003, for example, a severe heat wave led growers to harvest their grapes a full month ahead of schedule, and the wines that came out of that year were not especially well-regarded.

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"So 2003 is more likely to be the kind of summer you are going to get as climate change advances," he said.

Cook cautioned against alarmism, but said the study provides information growers should use to plan their seasons.

He also noted that the study focused only on wine regions in France and Switzerland, and that different conditions might exist in other wine-producing regions with different climates.

But the advantage of studying France lies in the sheer depth of its wine-producing history. Growing grapes and making wine have been an important economic activity for hundreds of years. For their study, Cook and his colleague, Elizabeth Wolkovich of Harvard, were able to refer to records dating back to the 1600s.