A brief history of winemaking
The
grapevine is one of the oldest cultivated plants that, along with the process
of making wine, has resulted in a rich geographical and cultural history. The
cultivation of grapevines (viticulture) predates written history.
Grapevines are projected to grow better
in warmer climates, and new regions may open up to viticulture. But changing
climates have the potential to bring about increased challenges for wine-grape
growers, both in the vineyard and the winery. All
images courtesy of Gregory Jones.
Archaeological findings in the Caucasian Mountains, near the town of Shiraz
in ancient Persia, indicate that viticulture existed as far back as 3500 B.C.
Vitis vinifera (the wine-grape bearing vine and one of about
60 species of the Vitis genus that is principally used for winemaking)
was first domesticated in this region and soon spread to Assyria, Babylon and
the shores of the Black Sea. The Assyrians brought the art and knowledge of
winemaking to Palestine and Egypt, and from there, the Phoenicians carried the
vine and its secrets around the Mediterranean and east toward Morocco and Portugal.
The Greeks and Romans learned the trade from the Phoenicians and proceeded to
spread their knowledge of wine throughout Europe. Ultimately, the Romans were
responsible for the first vineyard plantings in most of todays renowned
viticulture regions in the Mediterranean Basin. They cultivated the grapevine
in Bordeaux, the French valleys of the Rhône, Marne and Seine rivers,
in Germany along the Mosel and Rhine rivers, and even in the British Isles.
During the Dark Ages, grape growing declined throughout most of Europe. Viticulture
would have died out during this period had it not been for the Christian monks
who preserved the methods of viticulture and made vast improvements in cellaring
techniques. From the 10th through the 13th centuries, the monasteries controlled
the growing of grapes and the trading of wine. After the 15th century, viticulture
once again spread throughout Europe and enjoyed a renewed growth in popularity.
European explorers then carried the vine with them to their new colonies and
helped establish the industry in New World regions that were well-suited for
cultivation.
Terroir and climate
From this long history of development has come a distinct regionalization of
both the grape varieties grown and the wine styles produced. This regionalization
is intimately tied to both the landscapes and climates of these areas and has
become synonymous with the French term terroir (see story).
While not directly translatable into English, the term has come to embody both
the physical environment and cultural interactions that together produce a specific
wine style and its quality characteristics.
Although it is debatable which terroir component is most important landscape,
soil, climate or cultural practices climate clearly determines whether
a region can adequately ripen the fruit to produce high-quality wines. History
has shown that wine-grape-growing regions developed when and where the climate
was most conducive. For example during the medieval Little Optimum period (roughly
A.D. 900 to 1300), temperatures were up to 1 degree Celsius warmer, allowing
the planting of vineyards as far north as the coastal zones of the Baltic Sea
and southern England. Conversely, temperature declines during the 14th century
were dramatic, leading to the Little Ice Age (extending into the late 19th century),
and resulted in northern vineyards dying out and growing seasons so short that
harvesting grapes in southern Europe was difficult.
In general, the overall wine style that a region produces is a result of the
baseline climate, whereas climate variability determines vintage quality differences.
Todays viticultural regions for quality wine production are located in
narrow climatic zones that put them at particular risk from both short-term
climate variability and long-term climate change. Therefore, climatic changes
have the potential to bring about changes in wine styles or regional viability
altogether.
Our understanding of climate change and the potential impacts on viticulture
and viniculture (the science of making wines) has become increasingly important
as changing levels of greenhouse gases and alterations in earth-surface characteristics
bring about changes in Earths radiation budget, global temperatures, atmospheric
circulation and the hydrologic cycle.
Measuring the impact
In the wine world, it has become commonplace to hear that the (insert
your favorite year) was the vintage of the century, as it has become increasingly
easier to produce quality wines. Have these changes come about through better
grape-growing practices, better plant material, better winemaking techniques
or more beneficial climates? While it is clear that advances in both viticulture
and viniculture have provided the tools to produce better wines, climate is
the wild card that limits the geographical distribution of grape growing and
determines yield and quality differences between years and regions.
Although many have reasoned over the years that climate change may play an important
role in wine quality, Janice Lough and colleagues in 1983 were among the first
research groups to recognize the growing importance of climate change to the
industry, in an article published in the Journal of Climate and Applied Meteorology.
The authors showed that with warming climates, the growing seasons in Europe
should lengthen, and that wine quality in Champagne and Bordeaux should increase.
Today, we know that their results were largely correct, as the last 10 to 15
years have provided a wonderful string of vintages throughout much of Europe
and the New World.
Numerous other studies suggest that climate change may impact grape growing
and wine production. The potential impacts include changes in the geographical
distribution of viable grape-growing areas due to changes in temperature and
precipitation, greater pest and disease pressure due to milder winters, changes
in sea level (which could potentially alter the coastal zone influences on viticultural
climates), and the effect on vine growth and grape quality from increases in
carbon dioxide.
Until now, however, researchers had not conducted a global analysis of the impacts
of climate change on wine quality. Thus, my colleagues and I set out to examine
the observed changes seen in growing-season temperatures and to link the variations
to trends in vintage ratings (a common measure by which vintages are compared).
Using a general circulation model for 27 of arguably the worlds finest
wine regions, we were also able to project growing-season temperature changes.
Currrent trends
Growing-season
temperatures are a measure of the ripening potential for grape varieties grown
in climates that range from cool to hot. For example, Pinot Noir grapes are
grown in regions that have mostly cool climates, with growing-season temperatures
that range from roughly 14 to 16 degrees Celsius (for example, Champagne, Burgundy
and Northern Oregon), while Cabernet Sauvignon grapes are grown in regions that
span from warm to hot climates, with growing season temperatures that range
from roughly 16.5 to 19.5 degrees Celsius (for example, Bordeaux or Napa).
Climatologist Gregory Jones uses GPS to
fix the coordinates of a vineyard for further analysis. Research is showing
a correlation between changes in climate and wine-grape quality.
Our results show that from 1950 to 1999, the majority of the worlds high-quality
wine-producing regions saw growing-season warming that averaged 1.26 degrees
Celsius. The warming has coincided with a general increase in vintage ratings
over the last 20 to 40 years in these same regions. Although the strength of
the climate-ratings relationships varies by region, a 1-degree-Celsius warming
results in a 13-point increase in the ratings on average (on a 100-point scale).
Cooler climate regions, such as the Mosel and Rhine valleys of Germany, appear
to have garnered the most benefit.
At issue, however, is that many of these regions are either at or nearing their
optimum climates for the varieties grown and wine styles produced. Wine-quality
impacts from climate change are evidenced mostly through more rapid plant growth
and out-of-balance ripening profiles. A ripening period that allows sugars to
accumulate, maintains acid levels and produces the optimum flavor profile for
that variety will result in a balanced wine. In a warmer-than-ideal environment,
the grapevine will go through its phenological events (the combination of biological
events with climate) more rapidly, resulting in earlier sugar ripeness. While
the grower or winemaker is waiting for flavors to develop, the acidity is lost
through respiration, resulting in flabby wines (high alcohol with
little acidity retained for freshness). In addition, harvests that occur in
a warmer part of the growing season for example, August or September
instead of October in the Northern Hemisphere will result in hot and
potentially desiccated fruit without greater irrigation inputs.
Future trends
To examine future climates in the same wine regions, our study
analyzed output from a general circulation model from 1950 to 2049. A comparison
of two periods, 1950 to 1999 and 2000 to 2049, suggests that mean growing-season
temperatures will warm by an average 1.24 degrees Celsius over the wine regions
studied. The magnitude of these mean growing-season changes indicate potential
shifts in the relationship between climate and wine varieties for many regions
at or near a given threshold of ripening potential for varieties currently grown.
The projected changes are greater for the Northern Hemisphere than the Southern
Hemisphere. And the growing-season temperatures projected for 2000 to 2049 also
reveal significant changes in each wine region, with trends ranging from 0.18
degrees Celsius to 0.58 degrees Celsius per decade. Overall trends during the
time period average more than 2 degrees Celsius across all regions, with the
smallest warming in South Africa and greatest warming in Portugal.
Our analysis reveals that the impacts of climate change are not likely to be
uniform across all varieties and regions, but are more likely to be related
to a climatic threshold whereby any continued warming would push a region outside
the ability to ripen varieties that are already established. Cooler climate
regions have a greater ability to adapt to climate change, as they would be
climatically more conducive to ripening than some warmer climate varieties.
If a region, however, is already in a hot climate and warms beyond what is considered
viable for even the greatest heat-requiring varieties, then grape growing becomes
challenging and maybe even impossible.
Looking forward
The observed warming of the past 50 years appears to have mostly benefited
the quality of wine grown worldwide. However, the average predicted warming
in the next 50 years has numerous potential impacts on the wine industry
including changes in grapevine phenological timing, disruption of balanced composition
in grapes and wine, alterations in varieties grown and regional wine styles,
and spatial changes in viable grape-growing regions. Potentially even more important
is that climate change, through its direct impact on grape and wine production,
has the ability to indirectly bring about cultural change by altering long-held
regional identities.
The wine industry likely can adapt to the possible changes in climate, but not
without help. Today many of the Old World wine regions in Europe have stringent
standards by which varieties, yields, growing and winemaking techniques, and
wine styles are regulated to assure quality and maintain identities. For example,
the summer heat wave of 2003 in Europe produced very early harvests and some
challenging growing conditions that without irrigation (largely outlawed in
Europe) resulted in lower yields and out-of-balance flavors. Although New World
wine regions have fewer governmental constraints, growers and winemakers worldwide
will need the freedom to adapt to the potential changes in climate in both the
short and long term.
Perhaps a sign of things to come is being seen across Britain, where the past
decade or so has provided growing conditions not seen since the 13th century,
and grapes have ripened and produced drinkable wine. In the April 25, 2004,
London Times, John Walples and John Elliot report that a venture between
winemakers from Champagne in France and Kent and Sussex in England will result
in the first collaboration between the two regions. Perhaps the French have
seen one of the potential changes brought about by climate change shifts
in viable areas and are hedging their bets. This would appear to be the
case in at least one instance: A June 2, 2004, BBC story reports that English
sparkling wines either beat out or equaled Champagnes in a recent taste test
(see sidebar).
While the exact magnitude and rate of climate change in the future is unknown,
history has shown that climate and wine are intricately linked. However, predicting
future wine quality is also inexact. The question may be whether wine lovers
should buy a favorite wine from a favorite region to hold onto, just in case,
or whether they should appreciate change and simply enjoy the potential range
of new regions and new wines borne from a different climate.
Englands
wine renaissance
The pop of corks may one day replace soccer as the favorite cross-channel
rivalry between France and England. English wines, particularly sparkling
wines, are beginning to challenge Frances dominance in the Champagne
and wine market a trend some scientists say is linked to climate
change. Jay Chapman |
Additional Reading:
Gladstones, J., Viticulture and Environment. Winetitles, Adelaide, 1992.
Jones, G. V., White, M. A., and Cooper, O. R., 2004, Climate change and global wine quality. Climatic Change. (Submitted winter 2004: in review).
Stevenson, T., New Sothebys Wine Encyclopedia: A Comprehensive Reference Guide to the Wines of the World, 3rd ed., Dorling Kindersley, London, 2001.
Tate, A. B., Global warming's impact on wine, Journal of Wine Research 12, 95-109, 2001
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