KENT, England — A quarter-century or so ago, sheep might have been running around these lush green hills at the Gusbourne Estate in southeastern England, but on this fine autumn day a far different scene was unfolding.
A group of fruit pickers roamed around the rows of vines, picking bright clusters of chardonnay grapes. Another group stacked them high in green buckets, where they glimmered gold in the midday sun.
Gusbourne is not an estate in the conventional English sense, but a vineyard that, along with a steadily growing cohort of competitors, is producing some of the finest sparkling wine in the world these days.
And this was not a regular harvest. England’s record hot summer and limited rainfall have provided the perfect conditions for quality fruit and yields, leaving winemakers buzzing over what could potentially be the finest vintage ever for English fizz.
That is sending nervous tremors through the traditional overlords of the bubbly world in the Champagne region of France, whose long reign may now be threatened by the warming climate.
In a sense, a historic vintage has been brewing, so to speak, for decades in Britain. Climate change has steadily pushed up temperatures, providing ideal conditions for the chardonnay and pinot noir grapes that had sometimes struggled to ripen. If temperatures continue to increase at this rate, experts say, these grapes could be grown as far north as the upper reaches of Scotland.
But there is still plenty of land in the south for viticulture. Scientists from the University of East Anglia recently found that many of Britain’s most established vineyards are poorly located, and they identified 86,000 acres of prime land in the southeastern regions of Kent, Sussex and East Anglia that rival Champagne.
“English what?” asked Richard Chudley, 52, when he was offered English sparkling wine as an alternative to Champagne on a recent evening at a Fuller’s pub tasting in the Soho district of London.
After taking a sip, his face lit up. “Whatever I just tried is just as good as any bottle of fancy Champagne I’ve bought at the airport. I’m surprised.”
Bubblies have been a staple of English winemaking since the 17th century. In the 1660s, the scientist Christopher Merrett wrote that English vintners would carbonate their products by adding “vast quantities of sugar and molasses to all sorts of wines, to make them drink brisk and sparkling.”
But it is only in recent years, after tailoring viticulture to a warming climate, that English vineyards have started to produce high-quality sparkling wines.
At tastings, sips of English bubblies are often received with raised eyebrows and surprised smiles. Sommeliers describe the flavor as “vibrant,” “ fresh” and “zesty,” set apart from other wines by their lightness and acidity.
“It’s sometimes seen as a bit of a dirty word, but acidity is really important,” Charlie Holland, the chief executive and winemaker at Gusbourne Estate, explained on a recent day as he took a quick break from what he described as a “special harvest.”
“Acidity is what gives you vibrancy, it forms the backbone and makes things exciting to drink,” he said, pouring a glass of the Gusbourne 2013 vintage blanc de blancs that has won awards as the best English sparkling wine.
“That’s what we thrive on in England, and when we do it well the wines can be thrilling, packed full of flavor.”
The high quality has resulted in a shift in attitudes among sommeliers in expensive British restaurants, who have historically considered Champagne the only sparkling wine to serve.
This year, for the first time in the history of the Sommelier Wine Awards, a prestigious international wine competition, English sparkling wines won more gold medals than those from Champagne in a series of blind tastings.
“In previous competitions, the judges were pleasantly surprised when they liked a sparkling wine and found out that it was English,” Chris Losh, the competition’s director, said in an interview. “But now they actually expect it to be good, and if they taste bottles that are not good, they are quite hard on them.”
Champagne sales in Britain have fallen significantly over the last year. The falling value of the pound makes imports more expensive, and attitudes toward European products are shifting as Britain nears its withdrawal from the European Union, or Brexit.
Despite that, or perhaps because of it, some Champagne makers, including Taittinger, have started planting in England. The label has teamed up with a local partner and bought land near Chilham in southeastern England, and is expecting its first proper harvest next year and first release in 2023.
“I’ve always thought that we could produce quality sparkling in England,” Pierre-Emmanuel Taittinger said in an interview. “And that sends the strong message that wine is above Brexit.”
Climate change has had a big influence on English wines, and led to huge growth in the last five years, says Patrick McGrath, the managing director of the wine merchant Hatch Mansfield, Taittinger’s local partner.
“But there’s also been a real focus on planting on the right sites so that the vines are south facing, sheltered, ideally below 100 meters.”
Kent, one of the wealthiest, warmest and driest parts of the country, known as “the garden of England” for the abundance of high-quality fruit produced there, is emerging as a sort of British Napa Valley. Kent also has similar geological terrain to Champagne, with a strong concentration of chalk and limestone.
It comes perhaps as little surprise that some Champagne producers scorn any comparisons between French and English sparkling wines, saying that Champagne is in a league of its own.
“To say that the soil in England and in Champagne is similar is pure propaganda from the English producers,” said Thibaut Le Mailloux, a spokesman for Comité Champagne, a lobby of Champagne producers. “It is an insult to the French terrain to say so. The comparison is fallacious.”
But others are taking the challenge in stride.
“A good sparkling wine made in England is always better than a bad Champagne made in Champagne,” said a young Champagne producer, Aurélien Gerbais. “But I don’t think they’re significant competitors for us in the rest of the world.
“Are they going to be competitive in the British market?” he added. “If the Brits are as chauvinistic as we are, we might be sidelined.”
Stephen Satterfield, a former sommelier in San Francisco who recently toured English vineyards for his food magazine, Whetstone, says English fizz and Champagne have little in common other than being produced by the same methods.
“Champagne, with a few exceptions, is about really big houses, signature styles, excellent branding,” he said in an interview. “I think Champagne tends to be a bit more lush in style, whereas the English bubbles are a bit leaner and more intense.”
Mr. Satterfield also played down the comparison with California. “Napa became Napa because of people who bought cheap real estate many years ago,” he said. “Kent is already pretty expensive from what I understand, so that will limit the development happening quite as expansively.”
But there is one similarity. “The idea that it could be a place for wine tourism and luxury? Sure, I could see that.”