Behind the Forecast: Climate change impacting your wine?

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In the United States, the growing season typically lasts from April to October, and the...
In the United States, the growing season typically lasts from April to October, and the average temperatures for this period have increased by 2°F since 1970.(MGN)
Published: Oct. 20, 2023 at 9:52 AM EDT
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LOUISVILLE, Ky. (WAVE) - A changing climate may lead to our favorite wines tasting a bit different.

Geology, landscape, soil, and temperatures greatly influence the types of grape varieties that can be grown, along with the yield and quality of the harvest.

Cool climates favor pinot gris and chardonnays, while hot climates cater to zinfandels and cabernet sauvignon. Wine grapes are grown globally in regions where the temperature range during the growing season is typically 18°F. Pinot Noir grapes thrive in a relatively narrow temperature range during the growing season, usually around 2-3.6°F.

In the United States, the growing season typically lasts from April to October, and the average temperatures for this period have increased by 2°F since 1970.

A study found that a two-degree Celsius increase in temperature could cause many wine-growing regions to shrink by 56%. A four-degree temperature jump would leave 85% of wine-producing areas unable to create high-quality products. This study focused on the following varieties: cabernet sauvignon (kab-er-nay soh-VIN-yohn), chardonnay, merlot, pinot noir (PEE-noh nwar), riesling, sauvignon blanc (soh-vin-YOHN blahngk), and syrah (sih-rah).

Researchers have found that cool wine-growing regions like the Pacific Northwest, New Zealand, and Germany would be relatively unaffected by a two-degree Celsius rise in global average temperatures. These areas could become more suitable for Merlot and Grenache since they prefer warmer temperatures. Warmer growing regions, like Italy and Spain, would be the most impacted by warming.

Here’s why the temperatures are so important. It is harder for grapes to ripen in cooler climates. Less ripe grapes have higher acidity levels, which can give them a sour or tart flavor. Less ripe grapes have lower sugar levels, resulting in lower alcohol content.

Warmer temperatures aren’t entirely bad news. Grapes have higher sugar content, lower acidity, and darker color since they ripen faster in warmer climates. Higher sugar content means a higher alcohol content in wine.

There’s a negative side to the warmth, though. A growing season that’s too hot will force grapes to ripen too quickly. Excessive sunshine can cause crops to sunburn, and vines may stop growing to protect themselves from the heat.

Grapes require an ample amount of sunshine to ripen, regardless of temperature. Remember, climate change does not just mean warmer temperatures but also a change in the type and location of precipitation. More clouds and rain can lead to less ripe grapes. Too much rain can lead to higher grape moisture content, diluting the raw material used for wine production.

Producers have various options to adapt to changing conditions. Switching where certain grape varieties are grown could decrease potential losses by half for two degrees of warming and by a third for four degrees of warming. Growers have many options available, as there are over 1,100 grape varieties to choose from.

High temperatures and droughts in California have also forced wineries to change their practices. Some wineries have begun blending grape varieties to maintain their wine’s flavor, while others have invested in specialized irrigation to keep their farms running.

Warming temperatures could force vineyards producing Chardonnay grapes to switch to Merlot grapes. Winemakers may be required to move to cooler climates (whether that’s further north/south or at higher elevations).