But half a century from now, those regions may no longer be a safe haven, while the climate for growing in Denmark and neighboring countries may improve. Already, winemakers here are credited with creating white wines with crisp, structured flavors that are fading in southern climes where heat is reducing grape acidity.

“We’re trying to define the Nordic style of wine,” said Tom Christensen , who founded Dyrehoj Vingaard, Denmark’s largest winery, a decade ago with his sister, Betina Newberry . That includes investing in grape varieties with an acidic, fresh quality and an organic production without pesticides and sprays.

“People expect Nordic products to be cleaner,” he said.

The winery, on the lush Rosnaes peninsula, produces 50,000 bottles of premium white and sparkling wines, and he plans to expand. “If I had a Spanish vineyard, I’d hedge my bets by buying land here,” Mr. Christensen said. “In 20 years, you’d have a leading business in Europe.”

The hurdles are steep. Rising temperatures have improved growth conditions but are increasingly volatile, bringing acute heat one year and excess rain the next. That makes for uneven harvests. The amount of wine produced is still small, and most is consumed domestically, leaving little for export. Revenue from wine in Denmark, Norway and Sweden was an estimated €14 million this year, compared with €28 billion in France.

More wine will have to be produced for an industry to be sustainable, said Odd Wollberg, a winemaker in Norway. Mr. Wollberg, a former mechanic, and his wife took over the Lerkekasa Vingard winery, once considered Europe’s northernmost vineyard, in December from owners who planted vines a decade ago. Nearly a dozen other vineyards were established nearby in recent years.