Published online 2 May 2008 | Nature | doi:10.1038/news.2008.799

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Climate troubles brewing for beer makers

Rising temperatures are affecting European hop harvests.

Hopping worried: beer makers have climate change to contend with.Punchstock

With prices high and breweries booming, hop growers should be full of good cheer. Instead, they have furrowed brows as climate change threatens the finicky crop.

Plant scientists from Europe are attempting to breed new varieties that can withstand warmer climates, and are planning to install major irrigation systems where traditionally the hop plants haven’t needed additional watering. On Monday 5 May, plant scientists will hash through such issues at a hop conference at the Hop Museum in Wolnzach, Germany.

Hops initially served as a flavouring agent, and then a preservative in unrefrigerated kegs of beer that European colonial powers shipped abroad on sailing vessels. The trend continues; pale ales still have a hop-heavy taste, and nearly all beer contains hops as a preservative and flavouring agent.

The weedy plant is grown in lines up trestles, and a fruit-like cone is harvested to make hops for brewing. The plants currently grown in northern climates require moist soil, a hard-winter freeze and a hot summer. This formula has been disrupted by warming weather.

“I was absolutely sure it was affecting our hops by 1989,” says Peter Darby, a hop breeder with Wye Hops in Kent, UK. The nation's meteorological office data shows that the country has had unusually hot years since the late 1980s (see graph), and that is clearly being felt in hop fields. Within the past half-dozen years, Darby says, warm springs and milder winters began affecting the main varieties. Many hop vines sprouted early, went stagnant and produced little.

Hop hunt

As the changing conditions became more evident, biologists started heading to hotter climates in search of hop varieties that flourish there.

After the record heat of 2003 in Germany, the nation with the world’s largest number of hop-growers, plant breeder Elisabeth Seigner, of the Hop Research Institute in Hull, Germany, turned to Turkey for wild strains to create hardier new varieties. German hop growers recently received €6 million (US$9 million) from the European Commission to build the first major irrigation systems for this crop in that country, helping the plants to withstand hot summers to come.

Darby travelled to South Africa in 2005 to collect hop pollen for developing better varieties for Britain. Plants from these seeds are undergoing their first tests in fields in the United Kingdom this year.

And last August, researchers from the Hop Research Institute Company in Saaz, Czech Republic, dug up records of a 50-year-old United States-led hop collection trip to identify wild strains with desired traits in Arizona and New Mexico. Researchers at Washington State University are now working to develop these seeds into suitable varieties for new climates, some of which eventually will be shipped to the Czech Republic.

Not the only shortage

So far, the US hop-growing heartland in the Pacific Northwest has not been adversely affected by any warming trends, says Steve Kenny at Washington State University in Prosser; the fields there are already irrigated and so have the capacity to withstand warmer summers.

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But there could be more troubles brewing for beer makers in the United States and worldwide: last month Jim Salinger of New Zealand's National Institute of Water and Atmospheric Research in New Zealand warned that environmental changes were set to cause a crash in malting-barley production in New Zealand and Australia, with other areas perhaps to follow.

For now, strong ale lovers are left hoping that hop breeders can stay ahead of Earth’s warming trend, and prices for these crops don't soar too high. 

For a more serious look at the impact of climate change on world crops, see our news feature: A long dry summer .

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