EVERY AUTUMN, wine makers in Germany’s Mosel valley leave hectares of vines unharvested, hoping that a deep-enough winter freeze will allow them to produce the region’s famous ice wine. Yet the process is becoming a riskier business each passing year.

2019 was the first vintage in which no vintners in the nation were able to produce the sweet dessert beverage, according to the German Wine Institute, which cited a too mild winter. In order to make ice wine, producers in Germany must wait until temperatures drop below -7° Celsius (19.4° Fahrenheit), allowing grapes to freeze while still on the vine and creating a more concentrated juice.

“Global warming is progressing and it’s making it increasingly difficult,” said Thomas Loosen from the Dr. Loosen wine estate, which counts ice wine among one of its key products. “Many smaller vintners aren’t even trying anymore because the financial risk is too high.”

Climate change has come in the way of ice wine creation for several years now, with few producers being able make it amid increasingly warm winters and hotter summers, which can cause grapes to ripen earlier. Dr. Loosen’s last successful vintage was 2016, though the estate attempts to produce it every year.

In 2019 they left about one hectare of grapes for ice wine production, Loosen said. That plot size can translate to a loss of roughly 10,000 bottles if the grapes go unused. The retail price of a bottle of the 2016 vintage is listed at around €40 ($45) on some websites.

“If global warming continues the way it’s currently progressing, I could imagine that ice wine might some day be a thing of the past,” he said.

At the same time, German wine quality has also benefited to some degree from climate change, he added, with hotter summers helping traditionally cooler regions achieve more frequent and reliable harvests.

The volume of German wine exports grew by an annual 3% in 2019, a separate report said Tuesday. 2020 could be more challenging for overseas sales, the German Wine Institute said, as trade tensions, Brexit, and risks related to the coronavirus outbreak could increase competition. — Bloomberg