4.5 billion. An impressive sum. But just how large a number is it?

Well, let’s pretend you hit the lottery and won one dollar a second for twenty-four hours a day, 365 days a year, for the next 31 years. At the end of this non-stop cascade of greenbacks you would have amassed a billion dollars. String four and half of those billions together and you have a very large number, indeed.

By the way, it’s also the age of planet Earth—4,500,000,000 years old.

So, what are we to think when we’re told that the world’s climate has changed so significantly in just the last century that we are headed toward irreversible catastrophe. Just one hundred years of climate history out of the last 4.5 billion confirms the bleak future of our planet? Hmmmmmm.

If you have some skepticism about the claim, it’s understandable. Nonetheless, there is legitimate debate on both sides of the issue. So let’s set the discussion in the back room for now and ask the wine lovers’ question: If worldwide temperatures did rise significantly in the foreseeable future, what would be the impact on wine?

The delicate Vitis Vinifera grape species—which produces ninety-nine percent of the world’s wines—only grows between the 30° and 50° latitudes in both the northern and southern hemispheres. Travel outside these temperate zones and quality wine cannot be produced.

To better understand the sensitive nature of wine grapes, consider that Cabernet Sauvignon has a narrow window of optimum maturity that hovers around an annual average temperature of 60° to 68° Fahrenheit. Pinot Noir thrives best in the 57° to 61° range. These are very small temperature windows and highlight the “canary in the coal mine” characteristics of the grapevine.

One of the criticisms voiced about today’s wines is they are increasingly higher in alcohol, jammy and full-bodied. Many are produced in regions such as California, Australia and South America. Restaurant critics often claim these libations are not food friendly but heavy-handed, hedonistic fruit bombs that do injustice to fine cuisine.

Allowing the fruit to hang on the vine for two to three weeks longer than just few decades ago creates the opportunity for winemakers to craft such styles. This extended “hang time” increases sugar levels and decreases acidity contributing to the lush, over-the-top styles many wine-food connoisseurs find offensive.

However, another fundamental reason for the shift to these type wines is the trend in rising temperatures. Winemakers do it because warmer weather permits it and because such styles score well in competitions.

Over the last fifty years, records show Napa Valley annual average temperatures have increased 1.7° Fahrenheit. This rise, coupled with many winemakers’ desire to produce medal-winning wines, is altering the profiles of today’s bottlings. Increases over 3° Fahrenheit has been recorded in the Bordeaux and Burgundy regions of France since 1970. Such stylistic changes in winemaking may not have been as likely without the longer growing seasons these regions are now experiencing.

Yet, just over the mountains west of Napa, in Sonoma County, there have been virtually no temperature changes during the same time period. Ditto the Barossa Valley in Australia. This highlights the conundrum of global warming…it can occur in one region but not necessarily in another. And it begs the question, are these changes actually global?

If they are, what portends the future of wine?

Since the world’s wines are grown in specific latitudes, if warming did occur, these fertile bands would likely begin shifting in size, offering newer areas in which to produce wine grapes.

For example, while England produces little wine today, it’s possible Her Majesty’s subjects could increasingly focus on growing grapes and making wine if warmer summers and milder winters offered such opportunities. As in all human endeavors, the opportunity for profit would beget new markets.

Moreover, if the earth warms up a bit, not only will cooler climes start producing wine, it’s possible these newer areas of viniculture might ultimately create even higher quality wines than today. Since no one has been able to successfully cultivate many of these regions in the past, the nuances of the soil, air, sun and slope—together referred as terroir by the French—might reveal even better wine producing regions than we have today. Only milder weather and time would confirm such a scenario.

In fifty to hundred years from now, it’s conceivable Napa Valley’s reputation will fade as it produces cheaper, bulk quality grapes that today are grown in the warmer Central and Southern Valleys. Higher caliber fruit might well migrate north into Oregon and Washington State, further enhancing the reputation of these wine regions. And look for Canada’s emerging wine status to further accelerate.

In France, the challenge will be to change entrenched laws that today restrict certain regions to growing specific grapes, such as Chardonnay, Pinot Noir and Gamay in the Burgundy appellation. By the next century, Syrah, Grenache, and Mourvedre—grapes that like a bit warmer environment—might supplant today’s varieties. Meanwhile, the Champagne and Alsace regions to the north could inherit the classic Burgundian vines.

In Bordeaux, the distinction between Left Bank and Right Bank wines could begin to fade. The Left Bank, which borders the Atlantic Ocean, is cooler today than the Right Bank. This difference could be equalized in the future, blurring the quality and type of grapes grown in each region. A potential benefit for the Left Bank is that increased warmth could result in the vinification of even richer tasting wines.

Italy, Spain and Portugal would also see many of their most productive vineyards start drifting northward as winegrowers follow the more productive growing regions.

Since much of this worldwide change would occur over decades, viticulturalists could also begin to experiment with different clones of existing grapes, creating perhaps some new stunners worthy of 100 point scores. The unknown is a bit scary, but also exciting.

And let’s not forget the potential impact on winemaking in the Old Dominion. Our state is a bit south of center of where quality grapes can be grown. If our summers became much warmer than they are today, we just might find our future winemakers pulling up stakes and moving further north to create their tasty gems. Not a pleasant thought.

But, controversy swirls around whether all of these dire climate predictions will actually come to pass. Even some noted climate experts admit no significant overall warming trend has occurred in the last fifteen years.

One thing is fairly certain for most of today’s wine lovers, only modest, if any, changes will occur in our lifetimes. If there is an eventual geographical shift of the planet’s grape growing areas, it will doubtless present opportunities along with the inevitable losses.

Perhaps the one article of faith we can count on is that wine will still be produced and enjoyed as it has for the last 9,000 years. And the variety and quality could well be better than what we are currently imbibing.

Optimism is the hallmark of wine lovers. So no matter the reality of our future climate, tomorrow’s wine world looks as bright as a glass of Chardonnay.

Published in the March 19 weekend edition of the Fauquier-Times Democrat.