Climate change is altering the chemistry of wine

There were hundreds of emails from panicked viticulturists soon after the Glass Fire broke out in California. They wanted to know if they could harvest their grapes without making their wine smell bad.

Oberholster could only say that maybe.

Wait times were as high as six weeks for grape samples to be tested. They didn't know if it was worthwhile. In 2020, 8% of California wine grapes were left to rot.

Climate change is nothing new to winemakers. Warmer temperatures have been good for some in cooler regions, but bad for others. Climate-driven disasters have ruined harvests in Europe, North America, Australia and other places.

Climate change can affect grapes in a negative way. The quality and identity of wine is dependent on the chemistry of the grapes and the weather they are grown in. Climate change is causing growers and winemakers to worry that the wines they make will be ruined.

Karen MacNeil is the author of The Wine Bible and is a wine expert in the valley. That is the heartbeat of wine.

MacNeil says the greatest challenge is unpredictability. Today, every step is up in the air, even though producers used to know which varieties to grow, when to harvest the berries and how to ferment them. Under the changing and unpredictable conditions of today's warming world, researchers and winemakers are finding ways to preserve beloved grape varieties.

We spoke with experts fromBordeaux in France and the University of California, Davis, to learn more about how climate change is affecting the wine industry.

We were given an inside look at how every stage of winemaking is transforming to preserve desired flavors and aromas, and we got to taste a lot of wine.

The taste of climate change

Even the hardiest vines can be killed by weather extremes, but there's more to the climate threat than that.

Wine quality is dependent on achieving balance between sugar, acid and secondary compounds in the berry. Acid breaks down as the grapes mature, and sugar builds up in the berry. Chemicals beyond those essential to the plant's core metabolism accumulate over the season. Red grapes are protected against UV rays thanks to anthocyanins, a group of plants. To the vines, they offer defense against animals and pests.

Wine flavor is affected by many environmental factors, including soil types, rainfall levels and fog, all of which are encompassed in the French word "terroir." Oberholster says climate is the most important part of the experience.

When a region's climate changes, that can disrupt the balance of sugar, acid and secondary compounds by changing the rate at which they develop. Grapes accumulate sugar as they mature. The sweet flavor in grapes can be found at higher temperatures.