“The biggest finding that we had was that truffles were responding to these hot and dry summers,” says Steidinger. He and colleagues found that a temperature anomaly of just 3 degrees Celsius was enough to stop the production of truffle fruiting bodies altogether. As tree-growing seasons shortened, truffles also tended to get smaller. The relationship with trees is crucial since the truffle fungi grow directly on tree roots and provide their hosts with additional moisture and nutrients, while the trees share sugar with the truffles.

This year’s weather has hit truffle stocks in multiple countries. It was particularly hot and dry in the south of England over the summer, for example, and the UK’s national weather service, the Met Office, confirmed in September that it was the joint hottest summer on record. To date, 2022 has also been the driest year since 1976.

Two truffle hunters in England who spoke to WIRED say they have seen the effects of this firsthand. “This season the truffles have been very poor,” says Melissa Waddingham of the website Truffle & Mushroom Hunter. “The majority of them are small, in bad condition—a lot of insect infestation, and, yeah, not very many big truffles.”

Waddingham looks for the fungi along the south coast of England, from Dorset to Essex, where chalky soils provide the alkaline conditions that truffles favor. Usually she finds roughly golf-ball-sized fruiting bodies, but this year most have been pea-sized or so.

Sasha Dorey, in Dorset, uses her two Lagotto Romagnolo dogs to search for truffles in a friend’s orchard. Her experience chimes with Waddingham’s: “I’ve been working with truffles for 15 years, but I’ve only really noticed a difference to the way they’re growing this year.”

Steidinger’s study also revealed that even in the center of the Burgundy truffle’s range—which stretches from North Africa to the UK—some continental European populations were clearly threatened by rising temperatures.

“What appear to be single resilient species are actually mosaics of vulnerable populations,” says Steidinger. Notably, the main truffle-producing countries that most culinary aficionados think of—Spain, France, and Italy—are in the central part of the truffles’ range. So even in the old bastions of truffle production, climate change could take a toll, rather than just at the far-flung edges where you might expect temperature changes to be more dramatic.

The Burgundy truffle study has caught the attention of experts. “It’s quite surprising; we didn’t expect this of this species,” says Paul Thomas, director of Mycorrhizal Systems, a truffle cultivation company.

He praises the researchers’ methods and notes how this year’s elevated temperatures in Europe are already inflating truffle prices: “The summer truffle, it’s been trading for like €1,000 a kilo. It’s way in excess of what it is in a normal year.”

Increasingly, truffles are cultivated on plantations, including in places less prone to dry summers—Thomas mentions sites in Wales and Ireland that have produced truffles this year, some for the first time.

But in more heat-affected regions, cultivated truffles must be artificially provided with nutrients and a reliable water supply in order to fend off the effects of drought. Doing this long-term in the Mediterranean, for example, is possible, yet unlikely to be easy or cheap in the coming years. “The water reserves in these regions are dropping, and the availability of water for irrigation is declining as well,” says Thomas.

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