Rising temperatures in Europe due to climate change have affected the standard and supply of key ingredients in the brewing industrys’ world-famous wares.

Second generation brewer at Belgian brewery Brouwerij Boon, Karel Boon, admitted hotter conditions are making it increasingly problematic to source the raw materials needed for its unique Lambic beers.

Brouwerij Boon, which has for 40 years been brewing and blending to techniques dating back to the 17th Century, has reported that a drop in rainfall has affected crops, leaving grains that are too small for its Lambic production.

Also, its cherries are sourced from Poland for its Kriek and there have been poor harvests at times over the past decade.

In making its famous Geuze (a blend of one, two and three-year Lambic), Faro (sweetened Lambic) and Kriek (Lambic with cherries), Boon relies on particular Pilsner malt and unmalted wheat.

And, while it was expected that the turmoil with world temperatures would affect Boon’s ability to manage its traditional spontaneous fermentation through wild yeasts, it was access to the right types of malt that was causing most concern.

“There is clear science [in brewing] that global warming is present,” Boon said via Skype.

“The thing that creates an issue for Lambic breweries is the period in which you can brew beer is shorter.

“[For it to ferment] the bacteria have to be around 8C. But that cool period has shrunk to make your beer.

“But, and what is a problem not only for Lambic breweries but also for any other brewery, is that global warming causes harvests to vary very much.

“With harvests of barley and wheat for malt there can be great variations in those raw materials and that can be the issue.

“The quality of the malt is about the 50 per cent of the quality of the beer and that is more an issue than losing two or three days of brewing each year.”

Boon, who recently addressed an enthusiastic crowd during a special Lambic showcase at Perth’s Dutch Trading Company, highlighted that his business traditionally brewed in sections between October and April.

And he said that dry Belgian winters in recent years had affected production.

“We brew four times a day – it is about 500HL per day – four days a week. We brew 10-12 weeks of the year. There is plenty of spare room in the schedule for us even if the (brewing) period shrinks,” Boon said.

Brouwerij Boon is the biggest producer of Lambic beer in Belgium. It stores the developing brews in giant casks called foeders, which average around 8,000 litres each.

There are about 100 foeders at the brewhouse near the River Senne, 25km southwest of Brussels.

Boon also reported that it was stockpiling wood suitable as replacement staves for some of its foeders that were more than 100 years old, but it was becoming more difficult to find suitable quantities.

Climate change has become a strong topic of conversation amongst breweries over the past month.

A study published in the Nature Plants journal last month, and widely reported by major news agencies, warned the price of beer would rise significantly because climate change, particularly warming, decreases barley crops.

On average, then, global barley yields will decline between 3 per cent and 17 per cent in 60 years, depending on the severity of the weather, the study showed. It also suggested that as a result of the drop in barley supply beer consumption would fall 16 per cent.

The Outline website reported last week that in Montana, bumper stickers that read, “no barley, no beer” appear sporadically around barley-farming towns.

“The crop has been in turmoil since 2014, when irregular weather made the barley sprout too early for it to be malted,” the website wrote.

Barley production in the US was the lowest on record in 2017 because of drought. The same weather phenomenon was also affecting Australia’s stock of barley. The lower standard of barley would also mean hazier beers because of high protein levels.