It is autumn in Tuscany. Francesco Ventroni, a truffle hunter, steps through a burnt-orange and amber-colored wood, scattering the leaf litter with his feet. His dogs bound ahead. But the little Italian valley that he knows so well is warmer and drier than it used to be at this time of year. Streams that usually run down the hillside are absent. Those leaves on the ground don’t have their usual fuzzy covering of November frost. And Ventroni is wearing a T-shirt.
As he approaches a favorite spot, where he once lifted truffles weighing nearly half a kilogram out of the moist soil, he knows those memories will not be matched today. “My dog, in his own way, looks at you and tells you to go home because there’s nothing,” says Ventroni. “You wonder how that is possible.”
The truffles that Ventroni and his well-trained dogs hunt are the knobbly fruiting bodies of fungi that live in a symbiotic relationship with trees. Lightly shaved onto pasta or eggs, or used to flavor olive oil, truffles are considered a delicacy and, yes, a luxury. Record temperatures in Europe this summer have taken a toll on truffle stocks, pushing prices for some varieties sky high, to €1,000 (around $1,012) per kilogram or beyond.
The knack of a truffle hunter still counts for something, though. Against the odds, Ventroni has managed to unearth some reasonably large truffles this year, around 100 grams each. “I’ve been pretty lucky,” he says. Still, he found them in the few places where moisture has clung on in the ground, he adds.
A recently published scientific study has revealed new details about how climate change and more frequent droughts are affecting truffles. The fungi may not be a staple foodstuff, but researchers say that by studying them, we can improve our understanding of climate change—both in terms of the surprising impacts it can have and how quickly those impacts can unfold.
When lead author Brian Steidinger, at the University of Konstanz in Germany, went truffle hunting for the first time while researching the fungi, he decided to get as close to his subject as possible. Truffle hunters typically train dogs to catch the scent of truffles and reveal their locations in a forest. The Italian breed Lagotto Romagnolo is often considered the most adept at this. But Steidinger found out that human noses can detect the aroma too—at close range. “I just started sniffing the soil and I ended up finding six or more,” he says.
However, the chances of having such success in certain parts of Europe could dwindle over the coming years, as Steidinger and colleagues explain in their paper.
The researchers analyzed data gathered by about a dozen citizen scientists who carried out 1,781 truffle surveys at 20 sites in Germany and Switzerland between 2011 and 2018, a period that experienced notably hot summers. The species in question was Tuber aestivum, also known as the summer truffle or Burgundy truffle. Black and bark-like on the outside, the flesh is a creamy white color.
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“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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Meanwhile, truffle cultivation is spreading to many other countries. A 2020 study modeled how, under certain climate change scenarios, the total area suitable for truffle cultivation in the Czech Republic could actually expand over time. But there remain challenges in establishing a commercial truffle industry in the Czech Republic, says lead author Tomáš Čejka, as people there have limited knowledge about the fungi and how to manage plantations.
At a time when climate change is already displacing millions of people, it might seem “hoity-toity” to be concerned about truffles, says Steidinger. But there’s a good reason for considering them: “They represent sort of what we take for granted,” he says. “We might be considering things as insensitive or invulnerable that are actually sensitive and vulnerable.”
In the meantime, Ventroni keeps an eye on the forest. Although he also makes money by offering truffle-hunting experiences to tourists, if truffle numbers really begin to plummet, there will be excessive competition for them, he says, which could affect his livelihood.
Some friends who work in agriculture have advised him to try feeding the soil with rotten truffles, in an effort to spread the fungal spores around and encourage new growth. But you never know if it will work, he admits.
“The hope is that it’s going to start raining again,” he adds, noting how truffles do best when it is sunny and moist. But just the right amount of heat, light, and water is key. These things must be in balance, says Ventroni. “And we’re losing this.”
Interpretation for this article was provided by Adamá Faye.