Unusual Weather Leads to Dismal Harvest in California

In California, many olive farm­ers are scratch­ing their heads after a series of unusual weather events has left this year’s olive har­vest 25 per­cent lower than last year.

“I have zero olives and will not har­vest any­thing,” Jeff Martin, an olive farmer and award-win­ning pro­ducer based in Santa Clara County, told Olive Oil Times.

At his farm, roughly 35 miles south of San Jose, an unsea­son­ably warm period at the end of win­ter caused the olive trees to bloom. These blooms were then dam­aged by an early spring frost, which ren­dered the trees bar­ren for the rest of the har­vest sea­son.

“We are spec­u­lat­ing a very warm period in February 2018 woke the trees up and a freeze in March shut them down,” he said. ​“In farm­ing, you just have to live through the down years.”

Martin’s case is not an iso­lated inci­dent. Many coun­ties across California, but espe­cially in the north and cen­ter of the state, were affected by these tem­per­a­ture fluc­tu­a­tions. Even some grow­ers as far south as Ventura County reported frost dam­age.

“We won’t har­vest for a cou­ple of months still, but it is easy to tell that [our yield] will be much less, prob­a­bly a 50 per­cent reduc­tion,” Phil Asquith, the owner of Ojai Olive Oil, told Olive Oil Times. On top of the tem­per­a­ture fluc­tu­a­tions, Asquith said the hot sum­mer took its toll on his trees as well.

“Swings in tem­per­a­ture from cold to hot, a ​‘false spring’ fol­lowed by more heat, also sear­ing heat waves up to 120 degrees [all dam­aged our crop].” he said.

However, not all pro­duc­ers were impacted equally by the weather. Several from dif­fer­ent parts of California told Olive Oil Times that they were not affected at all by the late win­ter and early spring tem­per­a­ture fluc­tu­a­tions.

“We did not expe­ri­ence what oth­ers expe­ri­enced as we are a bit warmer than other areas,” Karen Bond, the co-owner of Bondolio in Yolo County, told Olive Oil Times. She expects to see a slight decrease in her pro­duc­tion this year, but attrib­uted it to being an off year.

According to the California Olive Oil Council (COOC), which rep­re­sents 90 per­cent of the state’s olive oil pro­duc­ers, there are more sto­ries sim­i­lar to those of Martin and Asquith than of Bond.

The council’s data indi­cates that California pro­duc­ers will press 2.8 mil­lion gal­lons of extra vir­gin olive oil this year; a decrease of 1.2 mil­lion from last year.

This is a dis­ap­point­ing fig­ure for Patricia Darragh, the exec­u­tive direc­tor of the COOC, but still not as bad as it could have been. Back in June, an unof­fi­cial esti­mate from the coun­cil fore­casted that the yield may have decreased by as much as 35 per­cent.

In fact, Darragh is opti­mistic that this is only a bump in the road for California pro­duc­ers and said that prices will not be affected. She is not alone in her opti­mism. Every sin­gle pro­ducer inter­viewed by this reporter, even those unaf­fected by the tem­per­a­ture fluc­tu­a­tions, said he or she expected to have a bet­ter har­vest next year.

However, there is no ques­tion in Darragh’s mind that the weather is respon­si­ble for this year’s sub­stan­tial decrease.

“My under­stand­ing is that it is almost all weather-related,” Darragh told Olive Oil Times. ​“Even though olive trees are alter­nate-year bear­ing, that has not been sig­nif­i­cant to date in California.”

The big ques­tion loom­ing for her and all of the state’s pro­duc­ers then becomes: will California become increas­ingly sus­cep­ti­ble to late win­ter thaws fol­lowed by early spring freezes?

Two plant sci­en­tists and an agri­cul­tural engi­neer told Olive Oil Times back in June that they thought California is becom­ing more sus­cep­ti­ble to these tem­per­a­ture fluc­tu­a­tions. There is cur­rently no data avail­able to con­firm whether or not this is the case.

“However, there has been some anec­do­tal evi­dence of [these] events,” Kripa Jagannathan, a mem­ber of the Energy and Resources Group at UC Berkeley, told Olive Oil Times. ​“So we are try­ing to dig into the data to see what we can find.”

Jagannathan is part of a team that is study­ing how the freeze risk for sub-trop­i­cal and decid­u­ous trees in California will be impacted by cli­mate change.

She said the team is still in the very ini­tial stage of their research, but does have one work­ing hypoth­e­sis: the last frost date is chang­ing more slowly than the rate at which the spring is warm­ing. This would lead to trees bloom­ing ear­lier in the sea­son and cause them to be more sus­cep­ti­ble to harm from that lin­ger­ing last frost date.

“If the last frost date advances at a rate slower than the phe­no­log­i­cal shift in bloom times, then trees are likely to expe­ri­ence an increased frost risk,” she said.

Paul Ullrich is the head of the UC Davis Climate and Global Change Group. He told Olive Oil Times that abrupt tem­per­a­ture fluc­tu­a­tions, such as the ones expe­ri­enced ear­lier this year in California, are caused by cold air escap­ing from the polar jet stream and blow­ing into lower lat­i­tudes.

“On the purely mete­o­ro­log­i­cal sidemid-lat­i­tud­es­these abrupt tem­per­a­ture fluc­tu­a­tions are nom­i­nally caused by arc­tic air intru­sion, where cold arc­tic air is able to escape into the mid­lat­i­tudes because of a weak polar jet stream,” he said.

According to data kept by the National Oceanic and Atmospheric Administration, polar intru­sions through­out the mid­dle of March low­ered California’s daily aver­age tem­per­a­tures sub­stan­tially com­pared with pre­vi­ous years. This phe­nom­e­non is likely to have lead to the frost events that dam­aged so much of California’s olive crop.

While there is no solid evi­dence link­ing cli­mate change to a weak­en­ing polar jet stream, Ullrich said this link should be inves­ti­gated fur­ther.

“Although it hasn’t been proven defin­i­tively, it is the­o­rized that under cli­mate change we will see a weaker polar jet because of loss of arc­tic sea ice, which would then lead to a higher prob­a­bil­ity of a cold air intru­sion event,” he said.

In other words, California pro­duc­ers may have to brace for more February thaws fol­lowed by March freezes.

• San Francisco Chronicle


• National Oceanic and Atmospheric Administration