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Weathering the Grapes

Climate change and what it's doing to the wine world


For over 400 years wine growers in Europe have kept meticulous records of the seasonal weather conditions in their vineyards. These records provide scientists material to study the changes in not only the weather over this period of time, but also the effect of rising temperatures on the timing of grape ripening and ultimately on the wines. More than many other agricultural products, grapevines for winemaking give a good view into the climate change’s agricultural impact, because seemingly small changes in weather patterns have a dramatic effect on the outcome of the grape harvest and the quality of the wines. For example, a week of cool temperatures or severe rainstorms just before harvest can have a significant bearing on the composition of the grapes. An overly cold or thunderous spring can limit the yield of the ultimate crop. Harvest details and other wine growing records and changes over time are easier to track for the grape than other crops.  And the changes, they are happening.

Historically, the areas of the world believed to be best suited for growing wine grapes lie between 30 and 50 degrees latitude in both the northern and southern hemispheres. Some winegrowing regions that are at the limits of these bands have been on the edge of the climatic possibilities, either too hot or too cold, when it comes to successfully growing grapes. Now, climate change will mean that some regions that are close to the upper temperature limit are likely to become too warm to support wine growing. Conversely, regions that were so cold they could barely ripen grapes sufficiently for wine are now likely to reliably ripen grapes. Other types of regions are affected differently altogether, for example because of changes in rainfall levels and timing. A lot of climate related change is already happening and surely much of the changes are still to be seen.


So what’s the big deal?

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Collage entitled “Climate Change.” Image courtesy of William Struby via Flickr (Creative Commons).

Climate change has already made significant and noticeable changes in grape harvests around the world.  For example, in Bordeaux they are picking the grapes 10 days earlier than in 1980. In Champagne they are harvesting 15 days earlier; in Australia eight days earlier. That’s a big difference in a relatively short period of time. Reuters has reported the following statistics: “According to the International Panel on Climate Change, 1983-2012 is likely to have been the warmest 30-year period of the last 1400 years in the Northern Hemisphere.” These warmer temperatures have an affect on grapes. One recent study by scientists Benjamin Cook (NASA Goddard Institute for Space Studies and Division of Ocean and Climate Physics, Lamont-Doherty Earth Observatory) and Elizabeth Wolkovich (Arnold Arboretum, Boston, MA and Organismic and Evolutionary Biology, Harvard University) analyzed 400 years of harvest data and other climate measures from vineyards in Western Europe. The study confirms that warmer temperatures are historically associated with earlier grape harvests and that climate change is thus contributing to the trend for earlier harvests in the past several years.

As the study finds, warm temperatures at the end of the growing season are essential for grape maturation. In a good growing season that would yield high quality wine, historically the vineyard would need to have a drought at the end of the season. Because dryer soil gets warmer than damp soil, a drought spikes the temperature and results in full ripening of the grapes and an earlier harvest in cooler regions. However, since 1980, temperature increases have been more dramatic, to the point that a drought is no longer required to reach the higher temperature necessary for an early harvest. So harvests in Bordeaux are now a full two weeks earlier than the 400-year historic average. This may not seem to matter right now, but as the researchers point out, climate change has led to significant changes in how and when grapes ripen. While more good vintages may occur now, future temperature rise is likely to reach a tipping point for the vineyards and wine quality is likely to diminish.

Of course, the next question is whether wine regions can just be moved. Can vineyards in Burgundy, Champagne, and the Loire Valley simply be replanted in cooler regions? The answer is that it’s not so simple. So many factors other than temperature affect the taste and quality of a wine – the factors we call terroir.


Storm approaches a vineyard in Champagne. Image courtesy of Felix63 via Flickr (Creative Commons).

What is terroir and why does it matter?

Terroir is the French word for the natural conditions that affect the vineyard, or even a portion of a vineyard, and the resulting wine. The many factors that combine to create a vineyard’s terroir include rainfall, weather, soil composition, prevailing winds, a nearby body of water, the slope of a hillside the vines are planted on, to name a few. These conditions influence the grapes and their expression in the wine, and temperature is but one element.

Scientists have even found that terroir also includes the microbes in the vineyard. One recent study finds that microbes – bacteria and fungi – found on the outside of the grapes can vary from one vineyard to another only a few hundred miles away. This may only confirm what European wine makers have long believed about the uniqueness of the yeasts indigenous to their vineyards. Consider that many European vineyards have been in their existing locations for hundreds of years. Many vignerons believe that after all that time, the yeasts in their vineyards have changed and become unique to their site and thereby impart individualized characteristics to their wines alone. So they will use only the “natural” yeast found on their site to ferment the wine, rather than purchasing yeast from outside.

We can examine but one component of terroir to show its impact on the wine. For example, a body of water near a vineyard can affect the vines in a few ways. If the region is very cold, such as the Finger Lakes region in New York, the nearby lakes stay warmer than the land in winter. The breezes that flow over the water send relatively warmer air over the vineyards, thereby allowing them to survive the extreme winters. In warmer regions, nearby bodies of water stay cooler in summer and send cooling breezes over the vineyards to allow the grapes to ripen more slowly, a beneficial factor for the quality of the juice.

In a further nuance on the impact of nearby bodies of water, the river east of the Sauternes region of Bordeaux sends misty breezes over the vineyards in the late summer to early fall mornings. These morning mists coupled with warmer afternoons are the perfect combination for the growth of botrytis cinerea, the mold that in just the right conditions will cover the grapes late in the season. This mold, also called “noble rot,” causes the grapes to lose much of their water, thus concentrating the remaining components in the grapes, including the sugars. The concentrated juice is then fermented to make the luscious, sweet Sauternes wine we love. It is not hard to imagine how difficult it would be to replicate this terroir elsewhere.


Noble rot. Image courtesy of koolbe via Flickr (Creative Commons).

Even if vineyards can be relocated to cooler regions, many existing regions are unique enough that moving to a new location with cooler temperatures but a different terroir will not produce the same wine. For example, the soil in France’s Burgundy region is a mixture of limestone plus limestone mixed with clay, all intermixed with fossilized sea creatures left from when this region was an ocean millions of years ago. This soil gives Burgundian wines their characteristic minerality and does not exist in other wine regions of the world. Simply moving the vineyards to a cooler region may approximate Burgundy’s past cooler weather patterns, but it would be all but impossible to replicate the soil and its significant effect on the wines. Further, a warming in Burgundy, which makes some of the world’s most expensive wines and where Pinot Noir has been grown since the 4th century, may become too warm for cold-weather-loving Pinot Noir’s best expression. Other grapes better suited to warmer summers may need to be substituted in this region, which will be no easy feat either, as described more fully below.

Colder regions could be sitting pretty

The rising temperatures brought by climate change are generally good for cold growing regions like Germany, northern Europe generally, and in particular the Champagne region in France. In colder years, winegrowers in these regions have a hard time getting their grapes to ripen fully. So warmer seasons will mean more consistently good vintages. But even though the grapes may be riper, the later harvests are likely to change the flavor profiles of the wines.


Hambledon Vineyard in England. Image courtesy of Dominic Lockyer via Flickr (Creative Commons).

One example of major changes in a cooler region is the effect of warmer summers on wine making in England. The south of England was once considered the northern limit for vineyards, and even then the grapes struggled to ripen. However, over the past couple of decades the changing climate has made England a real force in the sparkling wine business. British winegrowers are excited by their improved wine production, and they already have had a few good vintages this decade.

What is happening to warmer regions?

Climate change’s effects are more complicated in warmer regions. For example, the grapes are ripening in Australia between one and two days earlier every year. Not only are temperatures rising and harvests are earlier, but soil moisture is dropping, which as mentioned earlier also affects harvests and vintage quality.


Bass River Winery Vineyard. Image courtesy of Jon Lin Photography via Flickr (Creative Commons).

Even in more moderate climate regions, warmer temperatures have had a big impact. Take Bordeaux for example. The 2003 harvest was the hottest year on record in France, and led to a grape harvest a full month earlier than normal – the earliest French harvest ever recorded. However, as Elizabeth Wolkovich, one of the recent study’s authors noted, although that vintage was picked so early, the vintage was not a particularly good one.

How are winemakers changing to accommodate the new reality?

Some wine growers are moving, for example to Canada. One winemaker named Philip McGahan, has moved from Australia to Sonoma to Canada to follow the cooler climates and start his CheckMate Artisanal Winery. He reports that 30 years ago, in one major Australian region, the harvest started in early February while now it begins in mid-January or even in the first week of January.

McGahan says that to make great wines he had to move from warming Australia to a cooler region, and moved to California’s Sonoma County. Once there, he saw more rising temperatures, into what he calls the “upper limits in terms of optimal temperatures to produce premium quality wines.” So, to this end, he’s bought vineyard land in British Columbia to grow his Chardonnay and Pinot Noir.


Vineyard solar flare. Image courtesy of Brian Giesen via Flickr (Creative Commons).

Some Australian winemakers also have sold their vineyards in traditional regions and have bought vineyard land in cooler Tasmania, the island off Australia’s southern coast. Others are moving to higher elevations to escape the heat. In Chile, vineyards are moving farther south for cooler temperatures and more rainfall, or to higher elevations. And if there can be any question about whether this is really necessary, the enormous expense and effort of all of this upheaval would not be undertaken if not for the obvious impact of the changing climate. Alternative sentence: At the risk of stating the obvious, all of this upheaval is enormously expensive for vineyard owners and thus for consumers as well.

Another option for wine makers is to change the grape varietals grown in any affected region. In Europe, however, this will not be so easy. Over the thousands of years that Europeans have been making wine, they have discovered the best regions for growing certain grapes through centuries of study and experimentation. These determinations have been codified into laws and regulations that cover all kinds of specific vineyard techniques, rules for which grapes are permitted to be grown, and techniques for fermenting and aging the wine itself. Any changes to these longtime rules will need to be carefully considered and must go through approvals of the governing authorities.


What appears in wine cellars will be effected by these changes in weather. Image courtesy of Ren Kuo via Flickr (Creative Commons).

It’s a fool’s errand to predict how rising temperatures will play out as the years progress, but climate change is very real for wine makers now. •

Vicki Miller was a practicing attorney in Philadelphia for over 15 years and is the founder and president of Vinocity. A long-time student in formal wine study, she is WSET Level 3 Wines & Spirits Certified. Vinocity creates wine events for institutions, businesses and non-profits. Vicki developed the successful Art & Wine event program for a corporate sponsor of the Philadelphia Museum of Art, and the Wine and Literature event for the Raven Society of the Free Library of Philadelphia.


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