Challenges Await Growers As Mediterranean Basin Becomes Hotter and Drier

Climate change has a direct, mea­sur­able impact on olive farm­ing in the Mediterranean region. As a result, the vast major­ity of the world’s olive oil-pro­duc­ing areas have become a test­ing ground.

In recent years, sci­en­tists have begun to inves­ti­gate how new rain­fall pat­terns, which increas­ingly resem­ble those of sub­trop­i­cal envi­ron­ments, will affect European farm­ers.

Attention is also being paid to the new tem­per­a­tures being expe­ri­enced in tra­di­tion­ally hot and cool months, as well as how the habi­tats of olive tree pests are chang­ing.

“We have stud­ied the Mediterranean cli­mate in the books, with its unique and long-estab­lished char­ac­ter­is­tics,” Luigi Ponti, a cli­mate expert and researcher at the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), told Olive Oil Times.

“But the Mediterranean cli­mate will leave the Mediterranean region and travel north, a grad­ual process that has already begun and that will stretch across the cen­tury,” he added.

By ana­lyz­ing the cli­matic data com­piled by ENEA and other sim­i­lar agen­cies, Ponti said that he and his fel­low researchers began to notice how sen­si­tive the Mediterranean basin is, even to minor changes in the local cli­mate.

“From those mod­els we under­stand how the cli­mate is shift­ing and thanks to pre­vi­ous stud­ies, we can say that there is a sta­tis­ti­cally sig­nif­i­cant pos­si­bil­ity that sev­eral north­ern European regions will shift to the Mediterranean cli­mate,” he said.

“The Mediterranean itself will shift toward a dry, arid cli­mate, which has an obvi­ous impact on the whole agri­cul­tural sec­tor as well as olive grow­ing,” he added. ​“Our data show that this shift­ing will likely hit even more groves in the Middle East.”

In the rolling hills of south­ern Spain, where olive trees stretch out as far as the eye can see, even a rel­a­tively small increase in the aver­age tem­per­a­ture is being felt by olive farm­ers.

“In the last 50 years, the tem­per­a­ture has increased on aver­age by 1 ºC (1.8 ºF) in south­ern Spain,” Ignacio Lorite, a researcher at the Andalusian Institute for Agricultural and Fisheries Research (IFAPA), told Olive Oil Times.

“Although lim­ited, this increase has led to ear­lier flow­er­ings in olive farms as well as more heat stress events dur­ing flow­er­ing,” he added. ​“This hap­pened mostly in loca­tions where flow­er­ing did usu­ally occur at a later date, such as mid-May, at a time when high tem­per­a­tures are com­mon.”

According to Lorite, regions that typ­i­cally expe­ri­ence later flow­er­ing will be increas­ingly exposed to late-spring heat waves, which have become more com­mon.

“In the areas under rain­fed con­di­tions, water stress will gen­er­ate severe yield losses,” he said, espe­cially when ​“these water stress events coin­cide with the crit­i­cal peri­ods as flow­er­ing or matu­rity.”

While it has become increas­ingly evi­dent that Europe’s cli­mate is chang­ing, dif­fer­ent impacts are being felt through­out the con­ti­nent. As a result, there is no sin­gle cli­mate-related issue that will most promi­nently trou­ble olive grow­ers.

Instead, sci­en­tists argue that cer­tain prob­lems will be felt more by cer­tain regions. For instance, while sci­en­tists are record­ing notable changes in the rain­fall pat­terns in most of Italy, the same con­nec­tion has not been made in south­ern Spain.

“The effect of cli­mate change on rain­fall is not yet obvi­ous,” Lorite said. ​“Although drought peri­ods have been iden­ti­fied dur­ing the last years, these events have been recur­rent in south­ern Spain for a long time. Neither has an increase of the sever­ity or fre­quency of droughts been observed.”

While sci­en­tists are already tak­ing note of chang­ing weather and cli­matic pat­terns through­out the Mediterranean basin, pre­dict­ing how these will con­tinue to change is an even big­ger chal­lenge.

However, the experts told Olive Oil Times that a few changes can still be expected. Among these is a shift of the nat­ural habi­tats for cer­tain olive tree pests.

“Given the lim­ited tol­er­a­bil­ity of the fruit fly to the chang­ing tem­per­a­ture, it is pos­si­ble that out­breaks in the south­ern areas [of Europe] will decrease,” Ponti said.

According to Lorite, increas­ing cli­mate vari­abil­ity will have the great­est impact on the regions that already have fewest chill units – hours dur­ing which the ambi­ent tem­per­a­ture is around (but prefer­ably lower than) 7 ºC (45 ºF).

As the Mediterrraneran basin steadily becomes warmer through­out the year, some of its key olive grow­ing areas may no longer receive the nec­es­sary 300 to 600 chill­ing units that the trees require in order to flower.

Lorite said that this may cause flow­er­ing fail­ures and cited exam­ples of this in the south­west­ern regions of Andalusia. However, he added that the vast major­ity of south­ern Spain is still receiv­ing an ade­quate amount of chill­ing units each win­ter.

While the scope of the prob­lems pre­sented by cli­mate change are begin­ning to be bet­ter under­stood, all of the data col­lected by researchers does not nec­es­sar­ily trans­late into easy solu­tions.

Ponti, whose research is now focused on the European Union-backed MED-GOLD project, empha­sized how sift­ing through all of the newly-avail­able data and infor­ma­tion is among the biggest chal­lenges for sci­en­tists.

“We con­sider the Mediterranean basin to be a hotspot for cli­mate change because it is a sub­stan­tially lim­ited strip of ter­ri­tory lying besides a huge water basin, where every change in cli­mate is ampli­fied,” Ponti said.

“What we are try­ing to do is to turn the infor­ma­tion com­ing from the research into tools use­ful to make deci­sions, both for pol­icy mak­ing and indus­trial orga­ni­za­tions,” he added.

Olives, grapes and durum wheat are the three case-stud­ies used by MED-GOLD to deter­mine the impacts of cli­mate change on Europe’s crops. Adapting crops to the chang­ing cli­mate is the focus of sev­eral other stud­ies.

“Many dif­fi­cul­ties have been met in find­ing the use­ful adap­ta­tion ini­tia­tives for olive orchards,” Lorite said. At the moment, he believes, ​“the most effi­cient adap­ta­tion mea­sures are deficit irri­ga­tion strate­gies.”

While this approach does not ful­fill the opti­mal water require­ments for olive farm­ing, it can help to avoid water stress dur­ing crit­i­cal phases of the trees’ devel­op­ment, such as flow­er­ing.

Deficit irri­ga­tion can also bring rel­e­vant water sav­ings with­out hav­ing a sub­stan­tial impact on the final yield, Lorite said.

“For instance, with allo­ca­tions lower than 1,500 cubic meters (53,000 cubic feet) per hectare (2.5 acres), sat­is­fac­tory olive oil yields could still be achieved, while also obtain­ing high water pro­duc­tiv­ity val­ues,” he said.

“Although these results were obtained for the Andalusia region, they are valid exam­ples for any region with a high spa­tial vari­abil­ity in the weather con­di­tions,” he added. ​“Thus, local ana­lyzes of olive orchard behav­ior under cur­rent and future weather con­di­tions are crit­i­cal com­po­nents that always must be con­sid­ered.”

Other tools such as improve­ments of soil and irri­ga­tion man­age­ment have also pro­vided sat­is­fac­tory results, Lorite noted, still ​“most prob­lems arise for the orchards under rain­fed con­di­tions, where adap­ta­tion tools are very lim­ited.”

Other areas in which sci­en­tists are explor­ing pos­si­ble solu­tions include the choice of the cul­ti­vars bet­ter suited to adapt to changes.

Lorite explained that knowl­edge is very lim­ited on the sub­ject and while con­clu­sive results have not yet been reached, IFAPA is already coor­di­nat­ing sev­eral research projects designed to eval­u­ate the vari­eties less sen­si­tive to heat or water stress.

“Similarly, infor­ma­tion about chill require­ments and phe­nol­ogy of the dif­fer­ent olive vari­eties is cur­rently lim­ited,” Lortite said.

Among the goals of researchers is the iden­ti­fi­ca­tion of olive vari­eties with ear­lier flow­er­ing sea­sons.

“Recent stud­ies have high­lighted the low vari­abil­ity in the flow­er­ing date of 148 olive cul­ti­vars grown in the World Olive Germplasm Bank in Córdoba,” he said.

This reduced vari­abil­ity could make the selec­tion of the right vari­eties more chal­leng­ing.

“Similarly, the selec­tion of cul­ti­vars with higher resilience to the impacts of cli­mate change is a long-term strat­egy and sat­is­fac­tory results are unlikely to be achieved in the com­ing years,” he added.