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During the past year, discussions about the potential impact of “global warming” have dominated the mass media. Although the exact outcomes and causes are in dispute, few now doubt the existence of the phenomenon. What does it mean for the wine industry? As wine is all about long-term agriculture and entirely dependent on the weather, I’d say it means a great deal.
The eventual consequences of climate change on the wine industry are unclear, as are the possible effects on the rest of the planet. The real question is: Are the changes something we will only see in the distant future or are they something we’re living and breathing right at this moment?
When I was a graduate student in science education at Stony Brook University in the late 1980s, I did my master’s thesis on the subject of climate change and its potential effects on Long Island. The concept was, at the time, little more than a derided footnote in the public consciousness. Yet even back then the research was clear that climate change was real. I particularly remember conversations I had with Dr. Anthony D. Del Genio at the NASA Goddard Institute for Space Studies (GISS), at Columbia University. Dr. Del Genio is a planetary physicist who has been studying climate models since the 1970s. He is also a wine buff and had done some investigation of his own into the effects of climate change on the wine industry. Most important, I remember when he told me, “all of us will begin to feel the effects of climate change by the end of the 1990s.” He not only was prescient—he also had some really good data to support his contention.
Changes in Growing Days
One of the main tools used to track climate in agriculture is Growing Degree Days (GDD). This is a system that cumulatively calculates the average daily temperature of the growing season using a base of 50°F. Winegrowers have used this system for many years to determine the boundaries of local climate as well as helping predict the quality and timing of the vintage. Cooler regions have fewer GDD and warmer regions have more GDD. Here are some examples of GDD as described in the seminal textbook General Viticulture, by A. J. Winkler, published in 1974:
Region I < 2500 GDD (Geisenheim, Germany, Geneva, NY)
Region II 2501-3000 GDD (Napa, CA, Bridgehampton, L.I.)
Region III 3001-3500 GDD (Oakville, CA, Riverhead, L.I.)
Region IV 3501-4000 GDD (Lodi, CA, Sidney, AU)
Region V 4001 GDD (Fresno, CA, Tehran, Iran)
I looked at some more recent data from the past 20 years to see if anything new has turned up. For one, Northern California is becoming much warmer. The city of Napa, which used to be classified as a Region II back in the 1970s, is now averaging seasons that are well into Region III and often as high as Region IV. Other areas within Napa Valley and Sonoma have reached well over 4000 GDD in the past five years—approaching conditions that might make it difficult to produce quality wines in the near future.
Back East, things get a little more complicated. Data obtained for the Finger Lakes region since the 1970s show no statistically significant increase in GDD. It is surprisingly consistent, with average GDD hovering around 2600 for most areas around the lakes.
Long Island presents an entirely different story. When I first wrote and applied for the two local American Viticultural Areas—The Hamptons, L.I. in 1984 and The North Fork of Long Island in 1985—I used data that went back to the 1940s. According to that information, the North Fork (represented by Riverhead data) had an average of 2932 GDD while the Hamptons (represented by Bridgehampton data) averaged 2531 GDD. Over the past 11 years, the numbers look quite different. Since 1996, the average GDD for Riverhead is 3331 days, while the average for Bridgehampton is 2805—an increase of 399 and 274 respectively for these two regions. Though it is not a long enough period of time to draw a definitive conclusion, one can definitely see the trend; on Long Island as well as in California, an average increase of 300 to 500 GDD has been recorded since the 1970s.
Clean-Air Effect
Last summer I contacted Dr. Del Genio again and mentioned to him that I was going to write a piece revisiting this topic. I also wanted to get his thoughts on what has changed in his understanding since 1990 and what he sees in the future. Interestingly, he mentioned that he and his staff have begun to draw some new conclusions from the models used to predict climate change.
Del Genio stated that since the onset of Clean Air Legislation that began in the 1960s, the levels of particulates (i.e. dust, soot, etc.) in the air have decreased, which, ironically, has lead to higher recorded temperatures in the densely populated areas of the Northeast, Midwest, and California. These particles in the air, known as aerosols, scatter sunlight and make the light less concentrated—in essence, masking the warming effects of elevated CO2 levels.
The areas showing the greatest response to clean air legislation are showing the greatest rise in temperature today—as much as 2° to 3°F on average. This effect is seen on Long Island, since we are close to New York City, but he also mentioned our maritime influence, so important for moderating winter temperatures. Our reduced aerosols along with slight increases in water temperature are more than likely responsible for the increase in GDD. It also explains why a region like the Finger Lakes, farther removed from air-quality issues and with more of a continental climate, is presently showing less of a warming effect. This is one good example of just how complex a system our climate is, and why it is so hard to accurately determine future outcomes.
Future Forecast
As for the future, Dr. Del Genio stated that new climate models predict that we will experience increases of anywhere from 400 to 500 GDD over historical averages by the end of the next decade. I mentioned to him that I had run the numbers and seen this beginning to happen. He was not surprised; again, Dr. Del Genio was on the money.
Opinions among local wine veterans brought up a plethora of concerns for the future of the industry on Long Island. Alice Wise, the viticulturalist with Cornell Cooperative Extension of Suffolk County, believes that climate change “is and should be a topic of great interest to all those in agriculture.” She states that “from a purely selfish viewpoint, slightly warmer summer temperatures would benefit late-ripening varieties. However, we all share the same concerns about how warmer temperatures would affect all aspects of the environment, particularly the marine waters that moderate our weather so profoundly.” Ms. Wise is particularly concerned about elevated levels of ozone, which can create leaf injury and might be an even greater issue in the future, with increasing summer temperatures.
Veteran winemaker and industry leader Larry Perrine, who has worked both forks of the East End, worries about the potential for rising sea levels. “If sea-level rise occurs according to some of the models, it presents a big problem in coastal areas,” he said. “What about the rainfall? When rain increases, then disease pressure does also. Grape varieties that are disease-resistant become more important.” Perrine goes on to state that conversely, “if the weather becomes warmer and drier it could make the area more conducive to red wines with higher alcohol.” Given the choice, the latter scenario is one I’m sure most local wine producers would prefer.
Ben Sisson, a vineyard manager for almost 30 years on the North Fork, was also concerned about the uncertain effects of climate change on precipitation. “I think all vineyards will have to have irrigation available, as the dry stretches seem to get longer each year, Sisson said. “I don’t think it is necessary to water regularly, but the ability to get water to the vines if they need it will be very important.” Sisson states that the real difficulty in dealing with managing vineyards lays in the age-old uncertainty of weather prediction. “Vineyard managers have to deal with a crop that is in constant flux, and many of their decisions are based on experience gained from past seasons. If those parameters change, it will make growing grapes that much harder.”
Present Ramifications
To ignore the influence of climate change with regard to wine growing would be a mistake. When or how we will deal with these issues in our lifetime is another matter, but I believe we are beginning to. In the last five years we’ve just experienced the warmest on record (2007), the second warmest on record (2002), the warm and perpetually overcast (2003), and the extreme hot and dry followed by rains of biblical proportions (2005). Clearly, many industry insiders in California are addressing the issue today, seen by the numerous land purchases by wineries and viticultural speculators in the cooler areas of the Northwest.
In the future, a warmer climate may mean many things. On the positive side it may extend the length of growing seasons and allow us the ability to plant later-ripening varieties. It may even open up entirely new regions for viticulture in areas where vines have not been successful before.
Conversely, a warmer climate might mean the dilution and disappearance of terroir in certain regions, as well as some traditional wine styles we are familiar with—particularly those in the cooler wine-producing regions of Europe. Dr. Robert Pincus, a climatologist at the National Oceanic and Atmospheric Association, in Colorado, who has written extensively about the wine industry, states in the journal Gastronomica that “in an increasingly warm world, the particular associations between wine and place will be difficult or impossible to maintain.” He has concluded that “even where the impact of climate change is less dramatic, decades, even centuries of viticultural experience will be rendered irrelevant.” Aside from higher temperatures, climate models predict changes in the levels and rates of precipitation and, most important for Long Island, stronger and more frequent hurricanes, which could make life more precarious for everyone—winegrowers included.
The term we need to be using is not global warming—but climate change. As the name states, climate change is just that—it’s not only about warming, its about a change in a complex system, which we still do not fully understand, that could include a broad set of possibilities. One thing is certain—winegrowers have always learned to adapt and will certainly do so in the future, experimenting with novel varieties, defining new terroir, and developing unique wine styles. Perhaps we don’t know yet exactly what all those changes will turn out to be, but something tells me we’ll be much better off if we could listen more closely to people like Dr. Tony Del Genio.
Richard Olsen-Harbich is managing director and winemaker at Raphael winery in Peconic.
Did You Know?
On the local front . . .
- The first evidence of European grapes grown on Long Island was by Prince Nurseries of Flushing, in the late 18th century.
- Long Island has one of the longest and warmest growing seasons in the Northeast (220 days).
- Suffolk County is the largest agricultural county in New York State in sales of product.
- Long Island is the largest grower of European grape varieties on the East Coast.
About climate change . . .
- Some researchers have found that many rodents such as mice and squirrels have moved to areas of greater elevation, possibly due to changes in their habitat caused by climate change.
- Slight changes in evolution may be already occurring due to the earlier bloom time of many spring flowers and the resulting change in behavior of the animals that rely on them.
- Earlier-blooming flowers may also result in a longer and more severe allergy season.
- Researchers have shown that carbon-dioxide enrichment of pine trees for three years resulted in trees twice as likely to be reproductively mature, and produced three times as many cones and seeds.
Suggested Reading
- The Revenge of Gaia: Earth’s Climate Crisis and the Fate of Humanity, by James Lovelock and Crispin Tickell (Persius, 2007)
- The Change in the Weather: People, Weather, and the Science of Climate, by William K. Stevens (Delta, 2001)
- What We Know About Climate Change, by Kerry Emanuel, Judith A. Layzer, and William R. Moomaw (MIT Press, 2007)
- Earth in the Balance: Ecology and the Human Spirit, by Al Gore (Houghton Mifflin, 2000)
- Cool It: The Skeptical Environmentalist’s Guide to Global Warming, by Bjørn Lomborg (Knopf, 2007)
