Soon your beer might taste different. Blame climate change.

Generations of farmers in the sun-lashed green hills of Spalt have proudly tended to their hops plants, used for brewing beer, since the Middle Ages.

Asked what makes the native breed of Spalter hops so special, enthusiasts rhapsodize about their delicate, spicy aroma; their lightness; and the harmony and hint of bitterness the crop imparts.

The plant is so central to the town’s culture that signs advertising “Spalter Bier” can be found on nearly every street, many of them hanging from the half-timbered, red-roof houses that were built hundreds of years ago to store and dry hops.

But the crop and those timeworn traditions are being threatened like never before. The culprit is climate change.

The promise of a warming, drier climate has dealt a brutal hand to the hops industry across Europe. But it has been especially ruthless to Spalter, a crop that has sustained this tidy town of 5,000 in southern Germany for centuries.

After a punishing season of scorching temperatures, stretches of drought and bruising storms, the hops harvest in Germany last year declined more sharply than at any time since World War II. Native breeds like Spalter that naturally developed in cooler, wetter climates centuries ago suffered the most. This year’s harvest has just begun, but the Association of German Hops Growers has already projected that it will be below average.

The growers used to get one dry year and bad harvest each decade. “However, now we are experiencing a second dry year in a row for the first time,” the Association wrote last month. “Looking ahead, we need to expect more dry years.”

Those realities have raised a host of existential questions in Spalt — about the longevity of its crop, whether farmers will switch to newer, more climate-friendly varieties of hops and, if they do, whether brewers will buy them.

“It’s just important to us that the whole system works, that it works in the future as it has worked in the past,” said Andreas Auernhammer, a hops farmer. “That’s why it’s been around for so long. We hope that in 700 years it will still be around. Not for us, but for the children of our children.”

Auernhammer and other farmers here grow many types of hops, including newer varieties. The native, traditional varieties of hops such as Spalter occupy a special niche in the market, however. They are sold not only to German brewers making traditional pilsners and Kölsches but also to international companies, including the American behemoth Samuel Adams.

But rising temperatures and drought have made Spalter harder and more expensive to cultivate, making farmers more reliant on irrigating their plants — no small task in a hill country where water is ever scarce.

Auernhammer has stretched a series of black irrigation pipes above his crops. Last year, despite being cushioned by his irrigation system — considered one of the best in the town — he saw a 20 per cent decrease in his harvest from some parts of his field.

The difference between his fields and those without irrigation systems is vast. Row upon row of lush garlands of hops vines climb up from Auernhammer’s field. Across town, in a field that has not been irrigated, the plants are thinner and have fewer vines, with barely any leaves toward the bottom of their stalks. On those plants, there will be fewer hops to harvest.

In an effort to make irrigation systems more accessible to farmers, the Bavarian government has pledged a total of 40 million euros to build the infrastructure in the region.

But the issue of getting water to the fields is more difficult than simply laying down more pipes to bring groundwater, which is in increasingly short supply. Hops farmers, politicians and water managers are also pushing to get access to a huge nearby reservoir called the Brombachsee, where excess rainwater is stored.

Such efforts are particularly important to maintaining the Spalter hops. Newer varieties of hops harvested last year showed greater resilience in the heat, springing back after weeks of drought were ended by late rains.

“No one of us would have suggested or would have thought that the hops can recover that well,” said Sebastian Gresset, who leads the hops breeding research for the Bavarian State Research Center for Agriculture. “But the older varieties, they didn’t recover.”

For the last seven years, Gresset and his team have been breeding new varieties of hops designed to be more resistant to drought and high temperatures.

Some farmers have quickly embraced them, because they require less work and money to cultivate.

“As the man who does the contracts with all the farmers here in the region, I can tell you that nearly all farmers here would like to try out these new varieties,” said Frank Braun, chair of HVG Spalt, a hops-growing company. “But the producer, the farmer, has also always an eye on, ‘I must be able to sell that.’”

The problem, according to Peter Hintermeier, the managing director of BarthHaas, the world’s largest hops trader based in Nuremberg, is that brewers and customers have been reluctant to accept the new varieties.

“They want to have their special taste in their favorite beer,” Hintermeier said of beer drinkers. “And therefore also our customers, breweries, are very concerned. Because they want to meet the taste that customers want. And therefore, they are very afraid to change the taste of the beer.”

But the work to produce a similar taste is also up to the brewers, not just the growers, Gresset said, acknowledging that introducing a new variety of hops might force breweries to adapt their recipes.

“The climate is changing, but the consumers still are asking for the varieties which are hundreds of years old,” he said.

Some are already experimenting with the new breeds.

On a recent steamy morning here, a farmer carted out a crate of pilsners brewed with a newer variety and handed out samples for his colleagues to try. The taste was good, they agreed, but the brewer was not yet happy with the bitterness of the beer.

That is why, purists believe, there is just no substitute for the Spalter hops, climate change notwithstanding.

“There is no newly bred variety that can compete on the field of pure and fine hop aroma — just the traditional hoppy taste — that are provided by our traditional varieties,” said Braun. “That is the reason why these old land varieties, even though the climate is poor and the price is higher, will remain — they will not disappear. If you want to do these very fine beers, you just need it.”