Challenges Await Growers As Mediterranean Basin Becomes Hotter and Drier

Erratic and unseasonable rainfalls will face olive growers in Italy, while farmers in Andalusia may no longer receive adequate chill hours as winter temperatures rise.
Oct. 14, 2020
Paolo DeAndreis

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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.

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.- Luigi Ponti, cli­mate researcher, ENEA

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.

See Also: Climate Change Is Transforming How Plants and Soil Interact

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.

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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.

Local ana­lyzes of olive orchard behav­ior under cur­rent and future weather con­di­tions are crit­i­cal com­po­nents that always must be con­sid­ered.- Ignacio Lorite, researcher, IFAPA

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).

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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.

See Also: Native Andalusian Olive Varieties Could Be Wiped Out by 2100, Researchers Warn

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.


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