What Could Climate Change Do to European Hops by 2050? Re-reading the Yield and Alpha-Acid Projections

A 2023 Nature Communications study analysed long-term changes in European aroma-hop regions and modelled yield and alpha-acid content for 2021–2050.

Map of major European hop-growing regions and study sites — The analysis focused on major European aroma-hop regions. Source: Mozny et al. 2023

Table of Contents

First, a terminology correction: hops contain alpha acids
Yield declined between the early and later historical periods
Warming shifted hop phenology earlier
The model projected 4.1–18.4% lower yield and 20–30.8% lower alpha content
These are scenario results, not fixed 2050 outcomes
Adaptation is part of the result
Reference

First, a terminology correction: hops contain alpha acids

The previous article referred to iso-alpha acids in hop cones. The study actually measured alpha acids in hops. During wort boiling, alpha acids are isomerized into iso-alpha acids, which provide much of beer’s bitterness.

Yield declined between the early and later historical periods

Changes in hop yield, alpha content and cone-development timing — Observed historical changes in yield, alpha content and phenology. Source: Mozny et al. 2023

Comparing 1971–1994 with 1995–2018, average yield declined by 19.4% in Celje, 19.1% in Spalt, 13.7% in Hallertau and 9.5% in Tettnang, while Žatec remained relatively stable. Alpha content declined in all five regions.

Warming shifted hop phenology earlier

The start of the growing season advanced by about 13 days from 1970 to 2018, and cone development shifted 13–31 days earlier depending on region. This moved important ripening stages into warmer conditions.

Yield was strongly associated with rainfall deficits, while alpha content was particularly sensitive to high temperatures during cone development.

The model projected 4.1–18.4% lower yield and 20–30.8% lower alpha content

Model projections of hop yield and alpha-acid content for 2021 to 2050 — Comparison of the 1989–2018 baseline with 2021–2050 model projections. Source: Mozny et al. 2023

Relative to 1989–2018, the model projected yield declines of 4.1–18.4% and alpha-content declines of 20–30.8% for 2021–2050 at the five core sites. Alpha-acid yield per hectare was projected to fall by 25.3–39.5%.

These are scenario results, not fixed 2050 outcomes

The projections used three CMIP5 global climate models under RCP4.5. They remain useful evidence of climate sensitivity, but they are not a deterministic forecast. Cultivar change, irrigation, relocation, management and CO2 responses can alter future outcomes.

Adaptation is part of the result

The paper discusses moving hop gardens to cooler or wetter sites, irrigation, altered row design, reduced tillage, cover crops and breeding more heat- and drought-resilient cultivars.

For hops, adaptation is not only about tonnes per hectare. Alpha acids and aromatic compounds determine product quality, so climate resilience must protect both quantity and chemistry.

The study does not predict the end of beer. It quantifies why keeping today’s cultivars, locations and management unchanged creates increasing risk.

Reference

Mozny M et al. Climate-induced decline in the quality and quantity of European hops calls for immediate adaptation measures. Nature Communications. 2023;14:6028. https://doi.org/10.1038/s41467-023-41474-5