How Will Global Warming and Climate Change Impact the Wine World?

By Special Wine Columnist, Richard Olsen-Harbich

Will it be a brave new wine world?

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 dependant on the weather, I’d say 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 in the late 1980s, I did my Masters thesis on climate change and the potential effects on Long Island. At the time, the concept was little more than a derided footnote in the public consciousness. However—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 importantly, 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.

One of the main tools used to track climate in agriculture is Growing Degree Days or GDD. This is a system that cumulatively calculates the average daily temperature of the growing season using a base of 50 degrees 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 higher GDD. I’ve listed some examples of GDD as described in the seminal textbook General Viticulture by A.J. Winkler, published in 1974:

I        < 2500           (Geisenheim, Germany, Geneva, NY)   
II       2501-3000    (Napa, CA, Bridgehampton, L.I.)
III     3001-3500    (Oakville, CA, Riverhead,  L.I.)
IV     3501-4000    (Lodi, CA, Sidney, AU)
V      4001              (Fresno, CA, Tehran, Iran)

I decided to look at some more recent data from the past 20 years and see if anything new 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 past 5 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 2 local AVAs – The Hampton’s, 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 Hampton’s, (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. Although 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 300-500 GDD has been recorded since the 1970s.

This summer I contacted Dr. Del Genio again and mentioned to him 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. He 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 2-3 degrees F on average. This effect is seen on Long Island since we are close to NYC—but he also mentioned our maritime influence, which is 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, further 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.

As for the future, Dr. Del Genio stated that new climate models predict we will experience increases of anywhere from 400-500 GDD over historical averages, by end of the next decade. I mentioned to him that I had run the numbers and saw this beginning to happen. He was not surprised; again, Dr. Del Genio was on the money. When I asked him what stocks he would recommend though, he said he was only a physicist.

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 last five years, we’ve experienced years that were the 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 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 season 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, 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 NOAA 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.” His studies led him to conclude 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 importantly for Long Island, stronger and more frequent hurricanes, which could make life a little 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 that 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 DelGenio.

Comments

[Jason Feulner]

Richard,

I appreciate this report primarily for your reasoned and cautious approach to the topic. I am curious about the natural world and our effect upon it, but I am somtimes appalled at how irrational and politicized responses can be to such phenomena. I often find discussion of "global warming" to border on the unscientific if not hysteric, which is not the case with your article at all. Your emphasis on the term "climate change" is noteworthy.

Your assertion that particulate mitigation in the last 50 years has, unexpectedly, contributed to warming in metropolitan areas is especially interesting. Our most thorough data sets--those from the post-war period--are perhaps not as easy to rely upon as we thought! It's all a very complex matter.

I wonder if the relatively recent California wine backlash has much to do with the climate changes you've noted. If Napa has been getting warmer the past two decades, then perhaps these climate effects have translated directly into the huge, fruity, alcohol-laden wines that many of us deride in favor of the balanced, food-friendly wines that can be grown in New York state.

Interesting stuff--thanks!

[Terry Hughes]

This is a fascinating article. I second Jason's praise for its reasoned tone and empirical basis. It ought to be required reading for anyone interested in the ramifications of climate change -- especially the zealots on either side of the argument.