How 1930s American scientists came to think about the impact of climate on wine

In Europe and even beyond, the concept of Terroir dominates the idea of origins and the quality of Wine. There is a lot of debate about the term, but it generally refers to where the grapes are planted. It is not just about the soil but also the terrain and elements that it is exposed to – such as sun, rain, winds, seasons, and more. Although climate is considered a factor, the soil on which the grapes are planted is the foundation. Over centuries, this way of thinking was codified in Europe’s appellation controlee system (AOC), which means “registered origin designation.”

The traditional regions of wine-making and grape-growing were literally an ocean apart. What could be done in order to improve the wine quality of these new vineyards? It was a particularly bad situation in the United States, where Prohibition had forced many winemakers to go out of business.

The world is far away.

Albert “Wink’ Winkler and Maynard Amerine launched a campaign to revive California’s wine business after Prohibition was repealed in the year 1933. Winkler, the viticulturist, and Amerine, the oenologist, were both passionate about grapes and Wine. They believed California could produce wines to rival the best in Europe. They collected vine samples in Fresno, in the south, and Ukiah, in the north. Then, they traveled westwards to the coast. Many of these vines were planted in test vineyards so they could see how well they did in different climate zones. This helped them advise growers about the best grapes to grow on their land. They were also looking for other treasures.

Winkler and Amerine collected grapes over ten years from willing viticulturists, transforming them into more than 500 site-specific wines. In 1943, Winkler & Amerine had tasted and observed the seasonal variations in hundreds of small batches they made every year. They were able to identify specific grape varieties that would work best for certain regions. They could measure and taste differences between vineyards by expanding the vineyards they collected grapes from.

Winkler had a revelation after they visited California’s vineyards and studied the wines produced in these fields. He concluded that climate and region differences were most important in selecting varietals for high-quality Wine. This conclusion was reached in a counter-intuitive way.

He compared vintage years in Europe to non-vintage years and realized that the only difference was the temperature. In places like Bordeaux or Burgundy, a year of vintage was usually warmer. In California, he applied the same logic as he tried different grape varieties in various regions. He found that some types, like Zinfandel, produced better wines under cooler climates along the coast and in northern California. In contrast, others, like Alicante-Bouches, had sweeter wines in hotter temperatures in inland California and southern California. This observation was of global significance.

What to plant?

Winkler and Amerine developed a heat index to help California winemakers from Gallo Mondavi decide which varieties would produce the best Wine in their specific locations. Winker Index transformed California vineyards, as well as vineyards around the world, when viticulturists began to pay more attention to the climate. It allowed New World wine regions to select varieties that were best suited for the environment. This improved the quality of the wines.

Their research had a deeper impact on the selection of varietals. The Winkler Index measures the temperature throughout the growing season. However, the wine library and the aromas of the wines were the basis of their conclusions. Amerine Winkler and their team measured the sugar/acid ratio and other compounds found in their Wine to see how the climate wines reflected the climate. They observed how the wines changed with time and, in particular, in years where the weather differed from the norm.

The early observations of heat and its impact on wine quality have allowed historians, climate researchers, and winemakers to conclude that the climate is warming and changing the taste of the Wine. This is not only based on the acid/sugar proportions but also on how the hotter and sunnier seasons increase sugar in grapes and the alcohol content of the Wine, reducing acidity and throwing Wine out of balance. The vineyard may have produced consistently high-quality Wine from the 1930s to the 1990s, but now the wines are inconsistent.

It can be the opposite: a region such as Bordeaux, which was plagued with erratic weather and sometimes lost entire vintages due to hail, cold summers, or frost, had more consistent yields. This smoothed out the difference between vintage and non-vintage years. The warmer seasons in Bordeaux allowed for more fully ripened grapes, which made even inexpensive wines taste better.

As the climate warms up, this has many negative effects. The acidity in wines is reduced by hotter weather, resulting in them being flat, flabby, or puffy. Bordeaux experimented with blending new varieties into their iconic and legally mandated types of whites and reds to increase acidity.

Smoke is always present where there is fire

Could it be that there’s a hint of smoke on your Wine? Alex Maze/Unsplash

Wildfires are an even more frightening and difficult consequence of climate change. Fires don’t always destroy vineyards. Grapes are just water spheres. However, smoke from wildfires can contaminate wines made nearby, leading to smoke-tainted Wine, which tastes like burnt rubber or cigarette ash. Smoke that has blown into the vineyard, engulfing ripening vines, is difficult to remove. Winemakers can’t tell by tasting grapes if a wine is smoke-tainted because fermentation affects the taste of a wine.

Scientists around the globe are still trying to figure out what causes a wine to taste smoke-tainted and how to mitigate this. The increasing number of fires that have occurred in wine-growing areas, such as California, France, and Spain, has led to a growing concern. In the same year, two wildfires in France’s Bordeaux area burned over 20,000 acres of forest. The harvest for that year was not affected by the wildfires, but future years will be challenging for winemakers.

Adapting to the changing world

Winkler’s dismantling of the link between Wine, Terroir, and the wine-growing region gave wine producers the vision to produce Wine in places such as Canberra (Australia), Mendoza (Argentina), Sussex (England), and Ningxia (China).

Climate change has already changed the weather patterns in Europe’s wine-growing regions, which are the ones that have the most traditional notions about Terroir. Research is being conducted to help winemakers adapt to this changing world. This is a change that has already taken place in the Winkler Index and even the ancient AOC system. Plus ca change

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