How the El Niño Will Affect Olive Growers

After an incred­i­bly unusual three years of the cli­matic phe­nom­e­non known as La Niña, mete­o­rol­o­gists pre­dict that there is about an 80 per­cent chance of El Niño devel­op­ing by September or October.

The two phases of El Niño-Southern Oscillation (ENSO) pro­foundly impact the global cli­mate, includ­ing the world’s most pro­duc­tive olive-grow­ing regions out­side the Mediterranean.

The shift from La Niña to El Niño increases the prob­a­bil­ity of higher-than-aver­age rain­fall in California, Chile, south­ern Brazil and Uruguay while increas­ing the prob­a­bil­ity of drought in Australia and South Africa.

The devel­op­ment of El Niño does not directly impact the Mediterranean basin, which is respon­si­ble for 96 per­cent of global olive oil pro­duc­tion but is asso­ci­ated with higher-than-aver­age global tem­per­a­tures.

Michelle L’Heureux, an ENSO spe­cial­ist at the National Oceanic and Atmospheric Administration (NOAA), told Olive Oil Times that the amount of heat stored within the trop­i­cal Pacific Ocean has increased in recent months, one of the nec­es­sary con­di­tions for the devel­op­ment of El Niño.

“El Niño, to the first order, is a warm­ing of the trop­i­cal Pacific Ocean at the sur­face,” she said. ​“When it starts warm­ing in the east-cen­tral Pacific, that can also start chang­ing the pat­tern of winds and the pat­tern of trop­i­cal rain­fall. When that all hap­pens, then we have El Niño.”

The build-up of heat in the east-cen­tral Pacific cre­ates a phe­nom­e­non known as a Kelvin wave, where the built-up heat shifts from west to east along the equa­tor, warm­ing the east­ern Pacific.

Another indi­ca­tor that El Niño will likely evolve ahead of the olive har­vest in the Northern Hemisphere is the devel­op­ment of west­erly wind anom­alies respon­si­ble for chang­ing pre­cip­i­ta­tion pat­terns through­out the Pacific Ocean.

“Typically in the equa­to­r­ial Pacific, the winds blow from east to west, and with El Niño, the winds reverse,” L’Heureux said. ​“When the west­erly winds start, they help push more warm water to the east, we get more ocean Kelvin waves and plant the seeds of El Niño.”

While it is dif­fi­cult to attribute any sin­gle cli­matic event to ENSO, El Niño years tend to be hot­ter than the global aver­age.

“El Niño boosts the odds of hav­ing new records in global mean tem­per­a­ture,” L’Heureux said. ​“It does­n’t mean that it’s a fore­gone con­clu­sion, but cer­tainly the last big El Niño did help boost global mean tem­per­a­tures, and we saw records.”

“So I think there is a legit­i­mate con­cern that this year, we poten­tially have an El Niño devel­op­ing that we could also rival the global mean tem­per­a­ture records that we saw in 2015/16,” she added.

After a year in which hot and dry weather severely impacted the olive har­vest across much of the west­ern Mediterranean basin, the news of new record highs will cause con­cern among olive grow­ers.

Scorching tem­per­a­tures in March and April in south­ern Spain, the world’s most pro­duc­tive olive-grow­ing region, have already jeop­ar­dized the com­ing har­vest. The poten­tial for the phe­nom­e­non to con­tinue will keep pres­sure on sup­ply and prices, which are already at record highs.

While El Niño is asso­ci­ated with above-aver­age global tem­per­a­tures, the shift in rain pat­terns may pro­vide some relief for olive grow­ers out­side of the Mediterranean.

Olive trees are quite drought resis­tant, but they need rain dur­ing crit­i­cal devel­op­ment moments to spur oil accu­mu­la­tion. Generally, pre­cip­i­ta­tion in the autumn and spring is wel­comed by olive grow­ers. However, too lit­tle rain causes trees to aban­don olive devel­op­ment to con­serve water for other vital func­tions.

El Niño years are gen­er­ally asso­ci­ated with cooler weather and wet­ter win­ters across the south­ern United States. According to the NOAA, El Niño increases the like­li­hood of pre­cip­i­ta­tion in California from January to April.

While the news of its devel­op­ment will likely bring relief to many California olive grow­ers – some of whom expe­ri­enced sig­nif­i­cant pro­duc­tion declines in the 2022/23 crop year due to the state’s severe drought – L’Heureux said the devel­op­ment of El Niño does not guar­an­tee wet­ter win­ters in the state respon­si­ble for vir­tu­ally all U.S. olive oil pro­duc­tion.

Meanwhile, the devel­op­ment of El Niño has olive grow­ers in Chile (the sec­ond-largest olive oil-pro­duc­ing coun­try in the Americas), south­ern Brazil and Uruguay hop­ing for an end to the region’s unprece­dented drought, which cli­mate researchers say has been exac­er­bated by La Niña.

“La Niña has been the main dri­ver of the south­ern South America drought in recent years,” Leandro Díaz, an atmos­pheric sci­ence researcher at the University of Buenos Aires, told Olive Oil Times.

“La Niña gen­er­ated the pre­dom­i­nance of high-pres­sure con­di­tions in the region that are asso­ci­ated with low pre­cip­i­ta­tion,” he added. ​“More research is needed to fully under­stand the role of other fac­tors, such as cli­mate change, but undoubt­edly La Niña is the main cause for the drought.”

According to the NOAA, El Niño increases the like­li­hood of rain­fall in cen­tral Chile from June to September, cru­cial moments in olive devel­op­ment. The phe­nom­e­non also increases the chance of wet­ter weather in Uruguay and south­ern Brazil from September to January.

However, Díaz said the asso­ci­a­tion between El Niño and increased pre­cip­i­ta­tion in west­ern Argentina, the largest olive oil-pro­duc­ing region out­side of the Mediterranean basin, is unclear.

“Therefore, the impact on that region is much more uncer­tain,” he said. ​”Whether it has any effect will depend on how this par­tic­u­lar event alters the atmos­pheric cir­cu­la­tion over South America.”

While El Niño increases the like­li­hood of above-aver­age pre­cip­i­ta­tion in the Southern Cone, Díaz warned that the pre­ced­ing drought has been so severe that wet­ter weather can­not reverse some of its dev­as­tat­ing impacts.

“The drought of the last few years has been extremely severe in some regions, so they will need a large amount of rain to recover the pre­vi­ous soil con­di­tions,” he said. ​“Although we have a high prob­a­bil­ity El Niño fore­cast at this time, it is dif­fi­cult to deter­mine pre­cisely how much rain we can expect.”

“This has a greater uncer­tainty and is highly depen­dent on the region, the inten­sity of the event, and how it may inter­act with other cli­mate vari­abil­ity pat­terns affect­ing the region,” Díaz added.

While the devel­op­ment of El Niño may bring reprieve to some of the world’s drought-endur­ing olive farm­ers, the cli­mate phe­nom­e­non por­tends drier con­di­tions for oth­ers.

El Niño years are asso­ci­ated with hot­ter and drier weather in Australia and South Africa. Consequently, the phe­nom­e­non likely exac­er­bated the his­toric droughts in both coun­tries in 2017 and 2018.

“Although most major Australian droughts have been asso­ci­ated with El Niño, analy­sis of past El Niño events shows that wide­spread drought does not occur with every event, and the strength of an El Niño is not directly pro­por­tional to the rain­fall impacts,” Michael Conway, a mete­o­rol­o­gist at the Australian Bureau of Meteorology, told Olive Oil Times.

He added that Australia’s wet La Niña had increased the avail­able water stored nation­wide. This may help buffer the effects of poten­tial drought.

“Having three years of mostly La Niña phases of ENSO has increased the acces­si­ble vol­ume of Australia’s main water stor­ages since the low rain­fall year for most of Australia of 2019,” he said. Available water has increased by 82 per­cent from January 2020 to February 2023.

While the like­li­hood of El Niño devel­op­ing has increased recently, L’Heureux said March to May is a noto­ri­ously dif­fi­cult time to fore­cast, and mete­o­rol­o­gists would have a clearer pic­ture later in the year.

• NOAA