Climate Change and the Wine Industry

Published on: October 8, 2007

The temperature of the planet is rising every day. As global warming changes the climate, agriculture is being forced to change along with it. Crops that are extremely sensitive to weather nuances are facing some particularly unique challenges in the form of water scarcity and alterations in maturity cycles. Such is the case with wine grapes.

Due to the fragile nature of wine grape cultivation, which occurs in special microclimates in very specific, narrow regions, the climatic zones for wine grapes are extremely susceptible to temperature variations. Some rises in temperature have benefited the industry, opening up new areas to viticulture and improving overall quality (in places like Germany and England). But future projections could prove detrimental, or at the very least, force a region that produces one grape variety to produce a very different grape variety.

Gregory Jones, a climatologist and an expert in the field of viticulture and Professor of Geography at Southern Oregon University, says that the greatest warming trends are seen at night during the winter and spring. Winter hardening has the potential to be affected, as does season length. Overall wine style in a region is influenced by baseline climate. And climate variability determines vintage quality differences.

For example, Cabernet Sauvignon is grown in regions (like Napa and Bordeaux) with temperatures ranging between 16.5 and 19.5 degrees Celsius. Cooler climate varieties, like Pinot Noir, are grown in regions (like Northern Oregon and Burgundy) with temperatures ranging between 14 to 16 degrees Celsius.

If the temperature were to raise two degrees or more in a region ideally suited to Pinot Noir today, it could push that region outside of its ability to produce Pinot, and make it potentially more conducive to ripening warmer climate wine grapes. Grape growing of any variety could prove impossible if temperatures warm beyond viable levels.

"If a region is at the upper limit of Pinot Noir, then only in the average to cooler years does it make good wine. In the warmest years it makes inferior wine," says Jones. "Very few other crops have the varietal-climate differences that wine grapes do."

Climate change can also influence the balance of a wine. During a well-paced maturation period, grapes have a chance to ripen with optimal acid structure and flavor profiles. In environments that are warmer than ideal, grapes may ripen too quickly, have higher sugar levels and lose acidity, resulting in higher alcohol levels.

This is already happening in Australia, where red wine alcohol content rose from 12.3 to 13.9% from 1984 to 2004. The alcohol content of reds in Napa Valley also rose, from 12.5 to 14.8% from 1971 to 2001. Generally, wines with higher alcohol levels do not age as well, and the result is de-alcoholization, acidulation, and watering back to better balance the wines. The summer of 2003 appears to have been the hottest since 1370, yet shifts in the climates of wine regions have continued to occur over time, says Jones. A dramatic drop in temperature in the 14th century destroyed many of the vineyards in Northern Europe. Warmer temperatures in the High Middle Ages led to early harvest.

"Cool climate regions have historically been at the margins of suitability, only producing the best wine in the warmer years. But with climate change, these regions have seen conditions more like the warmer years, year in and year out," says Jones.

Longer growing seasons in some areas today are actually producing better quality Champagne and Bordeaux. Current conditions could be more destructive in certain regions, though. Jones says that many of the better known wine regions may be near or at their optimum growing temperature for high quality wine. Napa’s 17.5 degrees Celsius average temperature is expected to warm to 19.7 degrees Celsius by 2049, pushing it to the upper end of optimum growing conditions for almost all of the most common winegrape varieties.

In Europe, warming temperatures will likely limit winegrape growing to England, further north in France and Germany, and up in elevation in Spain, Italy and Portugal. In the U.S., research indicates that this type of warming will likely limit growing to the poleward fringes of existing regions, like western Oregon and Washington, higher elevations in the foothills and in the coastal zones in California, and upstate New York.

Washington's wine industry, in fact, has become one of the country’s fastest growing agricultural sectors. Over the last decade, the number of wineries in Washington more than doubled. Harvest for 2007 is expected to top 120,000 tons, reflecting a 9% increase from 2006, says the Washington Association of Wine Grape Growers.

So could Seattle become the new Napa? No one knows for sure. What we do know is that more and more evidence points to increasing human impact on our climate. Jones says that the wine industry, like any other agricultural industry, will likely have to make adjustments in growing methods, technology, genetics and plant breeding to adapt to our ever-warming world.