Tasting Climate Change: Growers Are Trying To Preserve Wine Flavor In A Warmer World

3-minute video explainer about wine and climate change.

Far from being a distant phenomenon primarily affecting people and animals in exotic lands, climate change is now something you can taste at your dinner table. This is the conclusion of my article in the latest issue of Scientific American, drawn from my own research begun a decade ago in the vineyards around my hometown of Sonoma in Northern California, as well as the work of colleagues from around the world. I explain how a changing climate is affecting taste and aroma compounds in grapes- the chemistry that ultimately shapes the flavor you experience when you sip a glass of wine. 

Winegrowers and winemakers are beginning to respond to these changes. Whether they can adapt enough to retain the unique flavors of your favorite reds and whites will depend on the rate of climate change, and the rate of innovation. 

Winegrapes are especially sensitive to climate. Thousands of different varieties have been selected over the centuries to match local growing conditions, ideally producing the optimal balance of sugar and acid, and color and flavor compounds to express the best of that site and that grape in the wine. 

However, with a warming climate, that balance is shifting. Hotter temperatures mean faster ripening, which means more accumulation of sugar and loss of acids. Yeasts ferment sugar into alcohol, so riper grapes are contributing to the recent global trend for higher-alcohol wines, which are perceived as “hot” and more bitter. Acids provide a sharp, refreshing taste (think of a crisp Granny Smith apple), so cool-climate wines such as Riesling may get less refreshing with warming temperatures. 

Climate also affects the accumulation of pigments called anthocyanins, which make blueberries blue and give red wines their characteristic hue. We are so influenced by color perception that even experienced wine tasters used red wine characteristics to describe the flavor of a white wine that had been tinted red. Grapes from warmer climates are generally lower in desirable color, and excessive warmth can also decrease related compounds called tannins, which help wine compliment food and give them texture, such as “chewy” or “smooth”.

Most of what we commonly perceive as taste is in fact provided by our exquisite sense of smell, and climate is changing the aroma compounds in wine as well. Our brains integrate sensory inputs from the five tastes we can distinguish on our tongues, and the vastly greater variety of possible aromas recognized by receptors in our nose, to produce our perception of flavor. 

Under optimal vineyard conditions, grape sugar accumulation and acid loss are in balance, and reach their ideal at peak flavor potential, when color is also optimal, creating a tight window for the best harvest time. Under warmer conditions, the optimal balance of sugar accumulation and acid loss occurs earlier, while the optimal flavor moment may not shift as much, making it difficult to find the best combination. The grapes may ripen too fast to reach ideal color. Credit: Graphic by Jen Christiansen. Originally published in Scientific American, a division of Nature America, Inc. (January 2015)

While research is ongoing to try to understand how the more than 1,000 aroma compounds identified in wine affect our flavor perception, many compounds appear to be sensitive to climate, particularly in the later stages of grape ripening. Some desirable compounds like rotundone, which gives Syrah its typical black pepper aroma, appear to accumulate more at cooler sites and in cooler years, so warmer-climate Syrahs have less of this character.  

My parents' vineyard in the hills above Sonoma.

Winegrowers and winemakers have many options to adapt to warming climates. Growers are experimenting with new wine regions, cooler locations within existing regions (such as moving from warmer valleys to cooler hillsides), trying new varieties better suited to warmer conditions, and farming methods that provide more shade on the fruit. Winemakers can use approaches including alcohol removal and acid addition to improve wine balance. Steps like these can go a long way towards preserving great wines under climate change.

Ultimately, though, there are economic and biophysical limits to this adaptation. There are also cultural limitations: the know-how and sense of place that growers cultivate along with the land over generations of family farming is not easily moved, and consumers have come to expect a distinct flavor profile from wines from their preferred regions. Great wine is grown, not made; it reflects its place of origin. If the climate changes even a little bit, local knowledge and skills that have taken generations to hone can become less relevant, even in familiar territory.

But the changes we’re facing in climate are not small ones. Under our current trajectory of fossil fuel use, scientists project that the global average temperature will increase 4.7 to 8.6°F (2.6 to 4.8°C) over the next few generations. Even the low end of this range would be the difference in annual average temperatures between the winegrowing regions of Napa and Fresno today. Currently, Cabernet grapes from cooler Napa are worth more than 10 times as much as those from Fresno- a difference of over $3,000 a ton. 

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Wine illustrates our deep reliance on nature to provide us with everything we need to live, and many of the things that make life worth living. We are in a moment of critical climate choices. Choosing to limit climate change gives us more options for a more healthy, thriving, fair, and delicious world- including more of the traditional flavors of your favorite wines.