Water, yeast, barley malt and hops. These are the ingredients for beer, the third most consumed beverage in the world after tea and water. Climate change has long threatened grain production, but a new study suggests it has also been affecting the production of another of its key ingredients, hops, for decades. In the main growing regions of Europe there has been a decline in both harvest and product quality for some time due to warming. Projected into the future, the work suggests that plantations in Spain and other southern European countries will be hardest hit.
It is believed that it was the Benedictine nun and doctor of the church Hildegard von Bingen who was the first to add hops to beer almost a millennium ago. At that time the drink spoiled easily. But the flower of Humulus lupulus, a plant from the Cannabaceae family (the same as hemp), is a natural antibacterial agent that gives stability to the broth by stopping the appearance of microorganisms. The secondary effect, which was probably not intended by De Bingen, was to add the aroma and bitterness that hops possess in abundance. Although Egyptians and Sumerians made beer thousands of years ago, the modern version of the drink is thanks to this German nun and her idea to infuse it with such bitter flowers.
Now a group of Czech and German scientists wanted to find out how the ongoing climate crisis is affecting hop production. To do this, they selected five of the best-known growing regions, three in Germany, another in Slovenia and one in the Czech Republic. This trio of countries covers almost 90% of Europe’s production areas. On the one hand, they examined the amount of hop flowers produced between 1970 and 2020. They also counted another important piece of information: the amount of lupulin hidden in the flowers. This resin contains alpha acids, which provide beer-like bitterness and determine the quality of the hops. They then compared the numbers for each crop with various meteorological parameters such as temperature, rainfall or hours of sunshine at critical moments of fruit formation and harvest.
More information
Their results, recently published in the journal Nature Communications, show that hop fruiting has advanced by up to 20 days over the past half century. And that has serious consequences, as Martin Mozny, lead author of the study from the Global Change Research Institute of the Czech Academy of Sciences, says: “With increasing temperatures, the phenological phases occurred earlier.” The problem lies in the shift in the generative phase of hops a period with longer days. “All of this has a negative effect on the amount of alpha and the aromatic content.” During the weeks of growth, when it usually reaches up to six meters, it needs a lot of light. But when it stops growing and it’s time to bear fruit, excessive heat can cause the flowers to die.
The further development of hop phenology had a non-negligible influence; Production was reduced between 0.13 and 0.27 tonnes per hectare depending on the area. In Spain the current average for a good harvest is 1.6 tonnes per hectare. Since the mid-1990s, the decline in returns has been more pronounced, ranging in percentage terms from 9.5% in Tettnang (Germany) to 19.4% in Celje (Slovenia). The other key variable is the presence of alpha acids. For hops from the Slovenian region, its concentration has decreased by up to 34.8%.
The research has allowed the authors to determine that water shortages and drought particularly affect crop yields. Meanwhile, excessive heat affects the concentration of alpha acids. Hops are a very demanding and sensitive plant. Cultivation is only possible at certain latitudes, ranging from northern Germany to northern Spain. Since it requires a lot of water and moisture, it is planted near rivers. But between the festivals of San José (March 19) and San Juan (June 23), when the plant awakens from its hibernation and rises several meters high, it needs many hours of light. The flowers bear fruit throughout the rest of the summer and are harvested between late August and late September. This entire cycle is now being altered by climate change.
Moment of hop harvest on the farm that Hijos de Rivera has next to the Mabegondo Agricultural Research Center in Galicia. Harvest in Galicia/ Hijos de Rivera Corporation
In a second part of their research, the researchers projected them into the future based on observations from the last 50 years, using a climate model with the most likely emissions scenario and thus a calculation of precipitation and temperature. Everything about hops is deteriorating: the harvest could decline by up to a further 18.4% and the alpha content in these areas could be between 20% and 30.8%. But the work attempts to apply its calculations to the whole of Europe. Outside these three countries, the main hop growing areas are in southern England, northern France and Spain, and further east in Croatia, Bulgaria, southern Poland and eastern Ukraine. According to their estimates, the southern production areas, especially Spain and Portugal, will have it the worst.
In Spain there are 621 hectares where hops are grown, from which 1,024 tons of hops were obtained in 2020, according to the statistics yearbook of the Ministry of Agriculture. To obtain one liter of beer, one gram of hops is required, which is added to the broth by infusion. More than 90% of Spanish production, which does not meet the needs of the national beer industry, is concentrated in two regions of León, particularly the region irrigated by the Órbigo River. Agronomist Javier Fraile is the technical director of the Lúpulos de León cooperative, which brings together the vast majority of the region’s producers and markets around 97% of León’s production. “We are at the southern limit of hop cultivation,” he remembers. The area is also climatically optimal, with sufficient light days and hours for this plant and “photoperiod is a key element that regulates flowering,” he adds.
“In the 1980s, powdery mildew plagues plagued us [un hongo] “They came out in August, now we have it two months early”
Javier Fraile, agronomist and technical manager of the Lúpulos de León cooperative
When it comes to the effects of climate change, Fraile warns that it is difficult to separate it from other factors. “The problem is that the different varieties don’t live forever. “The ideal is a production time of 15 years,” he emphasizes. Hop plants live about 20 years and do not produce the same amount in the first or last year. This could influence the results of the study, he says. But on the other hand, climate change is causing problems: “In the 1980s, powdery mildew plagued us [un hongo] “They came out in August, now we have it two months early.”
It was in the context of the First World War that the first attempt at industrial hop production was made. José Luis Olmedo, R&D&I project manager at Cosecha de Galicia, a company owned by Hijos de Rivera Corporation (the producers of Estrella Galicia), recalls: “It was the founder, José Mª Rivera, who introduced hops.” In reality, it was the agronomist Leopoldo Hernandez. The two joined forces to import hops because they feared that the Great War would prevent foreign purchases.
“The alpha acids in hops are very sensitive to temperature”
José Luis Olmedo, Cosecha de Galicia R&D&I Project Manager, from Hijos de Rivera Corporation
“It’s very noble,” says Olmedo, summing up the plant: “The alpha acids in hops are very sensitive to temperature. Its bitterness or aroma depends on the variety, but also on the soil, humidity and temperature.” Olmedo has been working on reintroducing hop cultivation in Galicia for almost 20 years. Due to the weather, this year’s harvest was smaller than previous years. The months of June and August were the hottest in the last decade and in April and May, when the plant awakens, rainfall was well below the average for the last 10 years. And Olmedo also draws attention to the problem of increasingly mild winters. “The plants start sprouting earlier and a late frost kills them.”
With such an uncertain future, Hijos de Rivera and other breweries are looking for ways to adapt to the new climate reality. The Galician brewery is carrying out a project with Ekonoke, an initiative by researchers from the Autonomous University of Madrid. Their idea is to grow hop plants indoors, in greenhouses and with controlled control of all parameters. Although their motto, “We’re on a mission to save the world’s beer,” may seem exaggerated, Olmedo recalls that they’re hoping for four harvests a year here compared to the annual harvest abroad. “This is our plan B,” he concludes.
You can follow THEME on Facebook, X and Instagram, or sign up here to receive our weekly newsletter.