But as the supply from the Mediterranean becomes more unpredictable, some bottlers are looking elsewhere as future sources of oil. Even some champions of Mediterranean oil, like Nancy Harmon Jenkins, author of “Virgin Territory: Exploring the World of Olive Oil,” recommend venturing further afield.
“I hesitate to say this because I love the Mediterranean and I want people to have Mediterranean olive oil,” she said, “but I think California is going to be more and more important in the years ahead and places like Australia and New Zealand.”
Between June and August this year, it was exceptionally hot and dry across southern Europe. In Spain, temperatures soared above 105 degrees Fahrenheit (40 degrees Celsius) in July. In Italy, rainfall was 30 percent below normal levels — and in parts of the country, much lower still.
Scientists with the World Weather Attribution program, a group dedicated to the study of extreme weather, concluded last month that the “the chances of seeing a summer as hot as 2017” had increased tenfold since the early 1900s, and the chances of a heat wave like the one that hit the region for three days in August, nicknamed Lucifer, had risen by four times.
“We found a very clear global warming fossil fuel fingerprint,” said Heidi Cullen, a climatologist who heads the program.
Ask Italian olive growers about the weather this year and you hear a wide range of answers. It rained on one hill. It didn’t rain on the neighboring one. One olive variety made it through the heat; another didn’t. Even in one orchard, one tree hung heavy with fruit; another barely had any.
Many said they would have to invest in irrigation. The one upside of the heat, they all said, was that the olive fly withered, too.
On an unseasonably warm Monday in October, Ms. Contini Bonacossi and her brother, Filippo, took me through their family estate, known as Capezzana, in the hills northwest of Florence. Here and there, tiny, dried-up olives lay on the ground. A few trees were bare. But many were drooping with fruit: fat, purple-green olives, the sight of which made Filippo exceedingly happy.
“He is very excited,” Ms. Contini Bonacossi said of her brother. She was less so. Capezzana would produce 20 percent less oil this year; as Capezzana’s sales chief, she would have to ration it out to her loyal customers.
Ms. Guidobaldi, for her part, was taking no chances. She started harvesting in late September, the earliest ever on the estate. It was still scorching hot. What if a freakish storm came and knocked the olives down?
“Bellissimo,” she said, caressing the olives she had saved. “I don’t have children. These are my children. You can’t just ignore them one year and then come back the next year and everything is O.K.”
On the southern edge of Tuscany, in a valley of scraggly oak, Riccardo Micheli didn’t have the luxury of saving his trees with water trucks.
Unlike Ms. Guidobaldi’s conventional farm, Mr. Micheli ran his, the Agricola Nuova Casenovole, according to biodynamic principles: he used no pesticides and left much of his land to wilderness.
This year, nature did not return the favor.
By June it was burning hot. The hills around his groves turned red, then brown, as though the seasons had forgotten themselves and June had turned into November.
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