Workers load a truck with grapes during the harvest in a Graves grand cru parcel on Oct. 5 in Martillac in Bordeaux. Jean-Pierre Muller/AFP/Getty Images

On a small parcel of land tucked into the gently undulating landscape of the Loire Valley, a region in central France dotted with historic villages, sprawling castles and lush orchards, François Blanchard and a crew of friends, neighbors and fellow winemakers pick organic grapes from the chateau's vieilles vignes, the old vines. This golden October afternoon is the first time the grapes will be picked in many years, and though some winemakers might have given up — the vines were thickly overgrown and lay abandoned in the years before Blanchard took over the family business — he is convinced they are worth salvaging. "They're like an elderly person," he says. "They have a wisdom we can learn from." Learning from the past is important at his family's Château du Perron vineyard, where everything is done by hand — and sometimes by foot. Blanchard, a bass player who came back to winemaking after more than a decade devoted to jazz, considers the link to nature and tradition to be the very point of this business. This weekend, there’s a horse named Joker among the grape pickers, patiently pulling a plow and turning dirt along the long rows of vines. The white grapes picked today will be crushed this evening in a hand-turned press to be made into sauvignon blanc. In two weeks, it will be time to harvest the red grapes, which will be sorted and stemmed by hand in wooden baskets, then pressed in buckets by bare feet to make cabernet franc. Coarse, fresh grape juice is drunk from jam jars; last year's wine is passed around as inspiration for this year's vintage. With dirt under the fingernails and grapes between the toes, it is hard not to feel a close connection to nature. Which is why winemakers have been among the first to notice the effects of climate change on their crops. Higher temperatures over the past few decades have meant earlier harvest dates and variations in grape maturation. No one knows exactly what the long-term implications of climate change will be on the wine industry in France — which, along with Italy and Spain, is responsible for almost half the world's wine production — but it’s a topic that has both winemakers and scientists concerned. France's income from wine and spirits reached a new record in 2012 with 11.2 billion euros in sales, reflecting 10 percent growth from the year before. The wine and spirits market is the country's second most important industry after aeronautics.

'It's our job to adapt'

A couple hundred miles from the bucolic harvest scene in the Loire, in the southwestern city of Bordeaux, scientists at the Institut des Sciences de la Vigne et du Vin are hard at work in shiny labs trying to figure out just what climate change might mean for France's long tradition of winemaking — and what to do about it. "The main change we can see is in terms of harvest dates. We are harvesting about two weeks earlier than we harvested two or three decades ago," says Serge Delrot, scientific director at the Institut. Many winemakers like Blanchard take the changes in stride. "Nature is like a huge encyclopedia of living things. Every day you turn a page and learn something new," he says. "It's our job to adapt." According to a 2005 study by Gregory Jones, who studies the effect of climate change on wine, the average growing-season temperature in 27 wine-producing regions around the world rose 2.3 degrees Fahrenheit in the last 50 years. Some regions — namely parts of Spain, Portugal, southern France, California and Washington state — increased as much as 4.5 degrees. Bordeaux wines have been lucky over the past few decades, enjoying some of the best vintages in their history. Hotter temperatures means that berries ripen more quickly, which makes for more sugar in the grapes and higher alcohol content in the bottle. "People prefer Bordeaux with 13 or 13.5 percent alcohol content," Delrot says. "But for places that started at 13 or 14 percent, they're now going higher than 15 percent, and that can be a problem." In France, anything above 16 percent alcohol can no longer be classified as wine. Wines that approach this figure — coming in at 14 or 15 percent — are less amenable to being paired with food and consumed over several hours at a leisurely meal. "You can feel it's strong, and you can't drink very much," he says. While the combination of higher temperatures, earlier harvest dates and higher sugar content may be working in Bordeaux, there's a sense that this won't last. "The situation cannot be globalized because it really depends on the region … It also depends on the topology of the vineyards and the grape varieties," says Delrot. "The fear is that if we go beyond a threshold, we'll lose these beneficial effects in the long term."

CHART: Bordeaux grapes could ripen differently Below, grapes (also known as varietals) commonly used in bordeaux blends. Bordeaux is producing some of its best vintages now. Though the varietals used most often in this region are not at risk from predicted higher temperatures, they will likely ripen differently, explains Gregory Jones, a climatologist at the Southern Oregon University. CHART: Burgundy's pinot noir grape at risk Signature burgundy wines come predominantly from two varietals. One of them, pinot noir, is the prize of this region, but with a narrow temperature range, it is difficult to cultivate. In the future, temperatures could be too warm for pinot noir. The second, chardonnay, has a wider temperature range in which it ripens. Source: Gregory Jones, Southern Oregon University

Areas bordering the Mediterranean, like the Languedoc region in the south of France, feel the effects of climate change differently from cooler regions. Languedoc's already full-bodied wines are becoming even more intense in the face of hotter and dryer growing seasons. Some winemakers, worried that subtlety will be overpowered by higher alcohol content, are responding by planting at higher altitudes. Both winemakers and scientists are working on ways to respond to climate change. Some short-term solutions include changing vineyard orientation from east-west to north-south and focusing on canopy management to help shade and cool the grapes. Longer-term solutions include developing grape varieties that are better able to withstand extreme temperatures and drought. "We still have a lot of ways to avoid the effects of climate change — at least for the next 20 or 30 years," says Delrot. "Then we'll see." The possibility of adaptation is what keeps those in the French wine industry optimistic when it comes to climate change, even in the face of alarming predictions for what the future may hold. A study published last year in April by climate-change ecologist Lee Hannah and others in the American journal Proceedings of the National Academy of Sciences predicted that the Mediterranean region could face a loss of 85 percent of its vineyard-suitable land by 2050. But Delrot has a different perspective. "We completely disagree with (the conclusions of the study)," he says, adding that he and his colleagues published a letter of response in the journal. One of the main shortcomings of the article, he says, was that it didn't adequately consider the winemakers' resourcefulness. "They've always been adapting to different environments, different moods, fashions or tastes of consumers," he says. "(Climate change) is just another challenge, and they will adapt one more time."

The bureaucracy of wine

Just as there is an onus on winemakers to adapt, so must the complex and bureaucratic system of French wine production evolve. The appellation d’origine controllée (AOC) system in France has for decades exerted a powerful influence on winemakers and markets. Created in 1935, the increasingly controversial classification system grants AOC status to wines that adhere to a strict set of regulations within their respective region. The rules include which grape varieties and winemaking practices are approved within a geographically defined appellation, which can be an entire region, a village or a vineyard. The AOC system explains why "Champagne" and "Bordeaux" have come to be associated with wines more than with the regions that produce them. Defenders of the system say it ensures quality; opponents say it leads to a certain standardization of wines for economic and marketing purposes. Jean-Luc Dairien, director of the organization in charge of regulating French agricultural products that fall under the AOC label, describes the system as an attempt to stay true to the terroir, or land. "It was a way of making a link between a product and the land on which it was made," he says. "It's a question of what, where and who: What are we talking about, who made it, and where does it come from?"

Preparing grapes during the 2012 harvest in Bordeaux. Patrick Bernard/AFP/Getty Images Although the AOC system may be strict with regard to quality control — with wine, this means regulating everything from grape varieties and maximum yields to irrigation and harvesting techniques — it is not impervious to evolution. "It doesn’t mean the terroir associated with AOC is a museum. It has to live and adapt to climate change, societal change, environmental change and so on," says Jean-Philippe Roby, a specialist in vineyard restructuring and the head of technology transfer at the scientific research institute in Bordeaux. Still, the basic idea behind the AOC system has remained the same since 1935, says Dairien, who lists three primary challenges facing it: the rising alcohol content of certain wines due to higher sugar levels in the grapes, the challenge of maintaining current grape varieties in changing environmental conditions and the potential need to rezone areas of production. This last possibility has been garnering attention both in France and abroad. Some well-known makers of Champagne have explored the possibility of growing grapes in southern England, where similar soil and a warming climate bode well for the region’s winemaking potential. "Maybe one day we'll have wine made in Sweden," Dairien says, laughing. Adversity is at the heart of the tradition, he adds. "Historically in France, it's in the zones the most difficult, the most arid, the poorest, where grapes were cultivated. These are people used to difficulties. France has been cultivating grapes for centuries, and winemakers have always found solutions. There's no reason this situation wouldn't be the same."

The future of French wine