Workers fan out before dawn to clip clusters of grapes destined to be transformed into Italy’s prized Franciacorta sparkling wine a full 10 days earlier than anticipated, as scorching temperatures brought the fruit to maturation earlier than ever.

Climate change is narrowing the window for harvesting wine grapes, forcing winemakers to make quick decisions when even a few days can mean the difference between a good vintage and a bad one.

“These are delicate, frantic moments, and everything has to work perfectly,’’ said Berlucchi CEO Arturo Ziliani, whose father, Franco, and estate owner Guido Berlucchi became the first winemakers in the northern Italian region of Franciacorta to produce sparkling wine using the “classic” method famously employed by France’s Champagne makers.

“We did not expect such an early harvest or such an acceleration in ripening,” Ziliani said.

Heat forces predawn picking under floodlights