Lebanon's Climate Is Becoming Less Conducive to Olive Growing

Olive grow­ers and oil pro­duc­ers across the Mediterranean basin have observed the chal­lenges caused by cli­mate change in the region.

New research now sug­gests that ris­ing sur­face tem­per­a­tures will sig­nif­i­cantly impact the region’s olive trees’ health and abil­ity to bear fruit.

A team of researchers focused on the cli­mate his­tory of Tyre, Lebanon, where olive trees have thrived for thou­sands of years.

They con­firmed that the cli­mate changes over time, slowly drift­ing away from ideal rain­fall and tem­per­a­ture con­di­tions for olive tree cul­ti­va­tion.

The research pub­lished in Nature Plants is based on ana­lyz­ing 5,400 years of pollen data from a 390-cen­time­ter sed­i­ment sam­ple col­lected in Tyre, 83 kilo­me­ters south of Beirut.

Once dated and treated, the pollen grains found in sed­i­ments offer deci­sive clues about tem­per­a­ture and other weather con­di­tions that accom­pa­nied the domes­ti­ca­tion of the olive tree in human set­tle­ments.

“We used the pollen data, not only from olive trees but also sev­eral dif­fer­ent species, to recon­struct cli­mate data over time,” Rachid Cheddadi, co-author of the study and a bio­di­ver­sity researcher at the University of Montpellier in France, told Olive Oil Times.

By exam­in­ing the sam­ple layer by layer, researchers were able to mea­sure the dis­tri­b­u­tion and vol­ume of pollen through time and asso­ciate it with cor­re­spond­ing cli­mate con­di­tions.

To com­plete the pic­ture, the researchers used the cur­rent cli­mate data, ref­er­enc­ing 325 olive-grow­ing areas in the Mediterranean.

By asso­ci­at­ing the datasets and their find­ings, the researchers found that opti­mal grow­ing con­di­tions for olive groves include an annual aver­age tem­per­a­ture between 16.9 ºC and 18.3 ºC.

“This thresh­old appears as the ideal con­di­tion for the opti­mal flow­er­ing and vital­ity of the olive tree, the best suit­able tem­per­a­ture for olive trees to grow,” Cheddadi said.

Further analy­sis of those data sug­gested that cur­rent and his­toric olive yields are impacted sim­i­larly by the same cli­matic and tem­per­a­ture con­di­tions.

“The more the con­di­tions change, mov­ing away from that thresh­old, the more the species is impacted,” Cheddadi said.

By study­ing the past and cur­rent rain­fall pat­terns, the researchers spec­u­lated that the lower-than-ideal rain­fall lev­els in Tyre may have resulted in the local olive trees alter­ing the chem­istry of the dru­pes, chang­ing the fla­vor pro­file and nutri­tional con­tent of the olives.

This result is due to the chem­i­cal reac­tion of the trees to the lower amount of water, which can decrease the num­ber of fruit borne by the trees.

The researcher noted that if the olive tree under­goes freez­ing tem­per­a­tures for an extended period, its tis­sues might be dam­aged.

“In the same way, if the olive tree is sub­jected to high tem­per­a­tures, those might impact pho­to­syn­the­sis, with con­se­quences on the tree’s health and pro­duc­tive capac­i­ties,” Cheddadi said.

Climate change mod­els for Lebanon and the Levant show the dis­tinct pos­si­bil­ity that many his­toric olive-grow­ing regions may no longer be well-suited for the trees in the com­ing decades.

“From those mod­els, we can see that tem­per­a­tures in those areas are going to exceed the thresh­old, and that might not be good news for the local olive tree pop­u­la­tion,” Cheddadi said.

The chal­lenges of cli­mate change are well-known to local grow­ers. Karim Arsanios, the owner of Solar Olives in north­ern Lebanon, told Olive Oil Times that his farm is con­tin­u­ously test­ing and adopt­ing new mit­i­gat­ing and adap­ta­tion strate­gies.

“Climate events are becom­ing more fre­quent and vio­lent, as we have wit­nessed recently in Lebanon,” he said. ​“During January, we wit­nessed tem­per­a­tures climb­ing as high as 25 ºC for about two weeks.”

“At Solar, we adopt a bio­dy­namic approach to agri­cul­ture,” Arsanios added. ​“We try to inter­vene as lit­tle as pos­si­ble, but given the cur­rent sit­u­a­tion and con­sid­er­ing pro­jec­tions for the next 10 years, we real­ize that we will be faced with more extreme weather events.”

The farm is study­ing ways to retain water more effi­ciently dur­ing the rainy sea­son. ​“And we are eval­u­at­ing when an irri­ga­tion instal­la­tion would be appro­pri­ate,” Arsanios added. ​“We are also try­ing to cre­ate an ecosys­tem that goes beyond sus­tain­abil­ity and becomes regen­er­a­tive.”

Predictions for how the cli­mate will change in the Levant are also pre­dicted to spread to the rest of the Mediterranean basin, which cli­ma­tol­o­gists con­sider a cli­mate change hotspot. The sur­face tem­per­a­tures of the whole region are ris­ing faster than in most other con­ti­nents and regions.

“For Lebanon, this is the sce­nario, also because it is located on the south­ern edge of the range for many European trees, such as oaks and cedars,” Cheddadi said. ​“This prob­lem that we face will first affect, of course, the coun­tries that are at lower lat­i­tudes.”

For local grow­ers, adapt­ing to new con­di­tions is a must. ​“I can say that olive trees have been in this area for almost 7,000 years, and just like figs, they are men­tioned both in the Qu’ran and the Bible,” Arsanios said.

“The olive tree played an impor­tant role in the econ­omy and civ­i­liza­tion over time,” he added. ​“It was used for trad­ing olive wood with cedar wood, as fuel for lamps and to bake bread, and it was con­sid­ered a sym­bol of beauty, courage and fer­til­ity. In Arabic poetry and lit­er­a­ture, there are a lot of ref­er­ences to the olive tree.”

“We can­not pre­dict the future,” Cheddadi added. ​“So many dif­fer­ent areas and regions in the Mediterranean might have dif­fer­ent out­comes. On top of that, in many coun­tries, there are sci­en­tists who can han­dle the sit­u­a­tion and make pre­dic­tions. Policies and adap­ta­tion instru­ments might be stud­ied that can greatly help in address­ing the chang­ing cli­mate.”

“At this stage, what we sci­en­tists are doing is to give a warn­ing that we must be care­ful and address the prob­lem,” he con­cluded.