A winemaker hands a glass of wine to former French prime minister Manuel Valls (center) at a vineyard in Vauvert on August 11, 2015. Photo: AFP

Just when it seemed 2020 could not get more awful for French winemakers, it has gotten worse.

With coronavirus lockdowns sending sales plummeting, some have had to turn their unsold stock into alcoholic hand disinfectant.

This is all the more depressing because 2019 was a vintage year in many of the country's wine regions.

But 2020 has also brought the creeping specter of climate change into sharp focus, as winemakers were forced to start picking their grapes in early August in parts of southern France - a whole month ahead of the norm two generations ago.

The first signs are not good, with a meager crop riddled with mildew from topsy-turvy weather.

In some vineyards, there are hardly any grapes left to pick.

The Agly valley, upriver from Rivesaltes, the village which gives its name to the renowned fortified wine, is the sunniest in France, with 300 days of sunshine a year.

Yet even here they have not seen a year like this with grape-pickers working under blistering temperatures nearing 40 C. 

Farmers have been forced to harvest by machine at night or handpick from the crack of dawn to keep the grapes at their cool best. 

"It is the first time I have seen anything like this, and I have been working in the vineyards since I was 17," 68-year-old Jean-Marie Dereu told AFP in his fields 40 kilometers from the Spanish border.

"When I was young, we started the harvest in September."

This year it started on August 5.

"We had so much rain in the spring, which was catastrophic, and in the summer the vines were devastated by mildew.

"Normally, the Tramontane sea breeze blows and dries the vines but this year there was no wind. And now it's almost a drought," said Dereu, who still works seven days a week.

"This year we are definitely going to lose money," he added as he climbed onto his tractor.

The French government say climate change is almost certainly to blame.

The environment ministry said that "on average harvests across France are taking place 18 days earlier than there were 40 years ago."

This was a clear "marker of global warming," it added.

In her laboratory in Rivesaltes, oenologist Anne Tixier is worried about the "disturbing" way the rise in temperatures has been affecting wine production as she tests the pressed grape juice straight from the vineyards. 

"We are going to end up growing Spanish grape varieties in England" if this continues, she said. 

"We have been watching harvests get earlier for 30 years," Tixier added. 

"We can no longer deny climate change. We have got to think about the future, maybe by using other varieties or hybrids to adapt" to global warming.