Understanding all the steps of winemaking is key to understanding why climate change threatens wine so profoundly.
The winemaking journey from grape to glass
Wine may seem like fermented grape juice, but every bottle carries a long story. Each stage—from picking the grapes to how they are fermented, matured, and bottled—leaves its mark on the final taste. Understanding these steps is key to understanding why climate change threatens wine so profoundly.
Harvesting the Grapes
Harvest timing is critical. As grapes ripen, sugar increases, acidity drops, tannins develop, and aroma compounds evolve. Winemakers aim for a balance—too early, and wine is sour and thin; too late, and it’s heavy and alcoholic. Decisions are based on tasting in the vineyard as well as lab measurements.
Each cut marks a moment of precision — harvest is the art of catching ripeness at its perfect edge.
Crushing and Pressing
Grapes are crushed to release juice. For whites, juice is separated quickly from skins to keep flavors fresh. For reds, skins, seeds, and sometimes stems remain during maceration, extracting tannins, color, and aroma. Early choices here help shape the wine’s style—crisp and light or bold and structured.
Fermentation
Yeasts convert grape sugars into alcohol and CO2, turning juice into wine. Some winemakers use native yeasts for unique vineyard character; others add cultured strains for consistency. Fermentation conditions and vessels influence taste and texture, combining the craft of the winemaker with the vineyard’s character.
Malolactic Fermentation
Most reds undergo malolactic conversion, where Oenococcus oeni bacteria turn sharp malic acid into smoother lactic acid known from yogurt. This softens the wine, balances acidity, and preserves structure, while tartaric acid maintains freshness.
Maturation
Wines are aged to develop complexity. Stainless steel preserves bright fruit flavors; oak barrels add texture, aromas, and depth. Barrel type, age, and aging time influence style and sensory profile. Some wines are bottled early for freshness, others mature for years.
Bottling
The wine is clarified, stabilized, and bottled. Early-drinking wines highlight fresh fruit, while premium wines continue to evolve in the cellar, developing additional flavors and complexity over time.
Terroir — the unique blend of soil, climate, and tradition — gives each wine its distinct identity. As climates shift, biosolutions help protect this delicate balance.
Climate change and its impact on grapes and winemaking
For vineyards, the pace of change matters as much as the change itself. Grapes once ripened slowly through a rhythm of warm days and cool nights. Now, they are being pushed into a race against heat. When ripening accelerates, the whole system is thrown off balance. Sugar, acidity, tannins, and aromas—the building blocks of typicity—shift together, creating a cascade of challenges for winemakers.
Faster Ripening and Earlier Harvests: As temperatures rise, grapes ripen faster. In France and Switzerland, each 1°C increase brings harvests about six days earlier4. In Germany’s Rheingau5, harvests now arrive 2–3 weeks earlier than in the early 20th century; in Burgundy6, nearly two weeks earlier than a century ago. Faster ripening reshapes grape composition, not just harvest dates.
More Sugar, More Alcohol: Accelerated ripening increases sugar, leading to stronger wines. In southern France7, potential alcohol rose ~2% between 1980 and 2001. Similar trends appear in Alsace, Australia, and Napa Valley, with climate change responsible for up to half8 the increase. Higher alcohol can disrupt malolactic fermentation, leaving wines harsher and less stable.
Higher Sugar, Lower Acidity: Rising sugar is accompanied by falling acidity. Malic acid breaks down faster in heat, reducing wine’s backbone. Low acidity affects freshness, aging potential, and stability, making wines more vulnerable to spoilage yeasts such as Brettanomyces9.
Aroma Shifts and Extreme Weather: Heat also alters aroma compounds. Research shows that the levels of terpenes — the natural compounds behind grapes’ floral and fruity aromas — tend to decline as temperatures rise10. Climate volatility, including droughts, water stress, and sudden frosts, further threatens production. In April 2021, frost in central Europe cut output 25%11 below the five-year average; in Burgundy, 80–100%12 of the crop was lost. A study13 warns nearly 90% of traditional lowland wine regions in Spain, Italy, Greece, and southern California could disappear by century’s end due to drought and heatwaves.