Grape Expectations

The English wine industry – once something of a national joke – is coming into its own as climate change has raised temperatures in southern Britain an average of three degrees Fahrenheit between 1961 and 2006.  Today, Britain has approximately 400 commercial vineyards.  Sparkling wines are beating their French rivals in international competitions.  “We’ve noticed the climate has improved consistently. The weather has improved, the ripening period has become longer, and year after year we’re getting quality fruit,” said Chris White, the general manager of the Denbies Wine Estate in Dorking, England’s largest vineyard at 265 acres.  Denbies anticipates an even warmer future and last year planted seven acres of Sauvignon Blanc vines, a grape originating from France’s significantly warmer Bordeaux region.

Scientists have been analyzing the effects of climate and weather on wine since before global warming became an issue.  Over the past 20 years, studies have analyzed the emerging impacts of warming temperatures on vineyards in Europe, the Americas, Australia and elsewhere, and modeled the possible effects over the next century.  They see accelerating change that the earth has previously not experienced.  “If we look at the best data we have — there’s some data that goes back 500 or so years, and some paleoclimate stuff going back much further — on balance, changes underway today are as big or bigger than anything in those records,” said Gregory V. Jones, a climatologist at the University of Southern Oregon who specializes in climate’s impact on wine.

To date, rising temperatures have had a mostly favorable impact on wine.  Jones led a study that found the average growing-season temperature in 27 prime wine-producing regions had risen 2.3 degrees Fahrenheit in the previous 50 years.  In the vineyards of Spain, Portugal, southern France, and parts of California and Washington state, it rose 4.5 degrees.  Jones also found that wine quality ratings rose with the temperature.

According to an article on the Environmental Research website, the world’s vineyards need to alter some of their practices to cope with climate change.  “The diversity of wine production depends on subtle differences in microclimate and is therefore especially sensitive to climate change.  A warmer climate will impact directly on wine-grapes through over-ripening, drying out, rising acidity levels, and greater vulnerability to pests and disease, resulting in changes in wine quality (e.g. complexity, balance and structure) or potentially the style of wine that can be produced.  The growing scientific evidence for significant climate change in the coming decades means that adaptation will be of critical importance to the multi-billion dollar global wine-industry in general, and to quality wine producers in particular.  Adaptation is understood as an adjustment in natural or human systems in response to actual or expected environmental change, which moderates harm or exploits beneficial opportunities.”

There is also the potential for a critical decline in grape production in the United States. “If current trends continue, the (premium-wine-grape production area (in the United States)…could decline by up to 81 percent by the late 21st century,” a team of scientists wrote in a study published in the Proceedings of the National Academy of Sciences. The culprit was not so much the rise in average temperatures but an increased frequency of extremely hot days, defined as above 35 degrees Celsius (95 degrees Fahrenheit).  If no adaptation measures were taken, these increased heat spikes would “eliminate wine-grape production in many areas of the United States,” the scientists wrote.

Winemakers in California’s celebrated Napa Valley naturally worry that their reason for being might become untenable.  Napa growers will adapt to climate change and continue making fine wines, Steve Matthiasson of Premiere Viticulture and Matthiasson Wines, said.  He does not anticipate extreme changes anytime soon.  “I don’t doubt any of their data or modeling, and I appreciate them tackling the important issue of climate change,” he said.  “But I think we are much more resilient here in Napa, and we’ll be able to adapt to the changing climate and continue to make world-class wine without losing land to production.”