Rising temperatures reshape southern European wine as alcohol levels climb and producers face new technical and commercial hurdles

Wineries across southern Europe are facing new challenges as climate change drives up temperatures in traditional wine regions. According to the European Environment Agency, these rising temperatures are accelerating grape ripening and increasing sugar levels in the fruit. As a result, wines now have higher alcohol content, which can disrupt their balance, alter their typical flavor profiles, and create technical and commercial difficulties for producers.

Since the 1980s, the average alcohol content in wine has increased by nearly 1% per decade, with global averages rising between 2% and 3%. Today, most Mediterranean red wines exceed 14% alcohol by volume. This trend threatens the freshness and aromatic complexity that define many classic wines from the region. High alcohol levels can also make fermentation more difficult and lead to higher taxes in several countries. At the same time, consumer demand for lower-alcohol wines is growing, driven by health trends and changing social norms.

To address these issues, winemakers are adopting a range of strategies. Some focus on vineyard practices to reduce sugar accumulation in grapes. These include introducing new grape varieties, adjusting cultivation methods, or relocating vineyards to cooler areas. Techniques such as early harvesting, canopy trimming, and applying antitranspirants to leaves can also help slow sugar buildup. Other approaches involve using less mature grapes or selecting yeast strains that produce less ethanol during fermentation.

In the winery, physical methods for reducing alcohol content are becoming more common. One widely used technology is the spinning cone column, which separates aroma compounds and then removes ethanol under vacuum at low temperatures. This process preserves delicate flavors but requires specialized equipment and is mainly used by larger producers.

Membrane-based techniques like reverse osmosis and nanofiltration have gained ground over the past 15 years. These methods selectively remove ethanol while maintaining sensory quality and are more accessible for smaller wineries. However, scaling up these processes can lead to challenges such as membrane fouling and higher operating costs.

Another method under study is partial vacuum evaporation during alcoholic fermentation. This technique removes alcohol from fermenting must while allowing yeast to continue producing new aromas. Trials in France with varieties like sauvignon blanc, grenache rosé, and syrah have shown promising results. The process not only reduces alcohol but can also increase acidity and concentrate polyphenols due to water removal.

For post-fermentation desalcoholization, a two-step process is often used: first, reverse osmosis or nanofiltration extracts a permeate containing alcohol and water; then distillation or membrane contactors separate out the ethanol before returning water to the wine. This approach minimizes aroma loss compared to direct distillation at atmospheric pressure.

Recent research has explored combining osmotic distillation with pervaporation to recover both ethanol and water from wine processing streams. In one study with tempranillo red wine, this method reduced alcohol from 14% to 11% by volume while recovering most of the extracted ethanol as bioethanol and recycling purified water back into the process. Although some aroma compounds were lost—especially aliphatic alcohols and ethyl esters—aromatic alcohols were largely preserved.

European regulations have adapted to these developments. The EU now recognizes two new categories: "dealcoholized wine" (≤0.5% alcohol by volume) and "partially dealcoholized wine" (between 0.5% and 8.5–9%, depending on region). Producers are allowed to reduce a wine’s original alcohol content by up to 20%.

Despite these advances, reducing alcohol by more than 1–2% often changes a wine’s sensory profile and increases production costs due to investments in new technology or vineyard management practices. Maintaining quality, authenticity, and economic viability remains a significant challenge for winemakers adapting to climate change.

Projects like CLIMED-FRUIT, funded by the European Union’s Horizon Europe program, aim to share innovative practices across regions to help fruit growers—including grape producers—build resilience against climate impacts. As Mediterranean vineyards continue to adapt, collaboration between researchers and producers will be essential for preserving both tradition and quality in a changing environment.