` The Toll of Climate Change on California Olive Oil - Olive Oil Times

The Toll of Climate Change on California Olive Oil

Jan. 14, 2014
Marcel E. Moran

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Winter storms over the hol­i­day sea­son no longer just make us think of flight can­cel­la­tions and school clos­ings, but also how cli­mate change bears its face in the increase of seri­ous weather and extreme tem­per­a­ture shifts. This is par­tic­u­larly rel­e­vant for agri­cul­ture, and has changed the way farm­ers and ranch­ers in California, as well as the rest of the coun­try, con­sider how, when, and where they plant their crops.

The most imme­di­ate issue for the olive affected by cli­mate change is rain­fall. For California, 2013 was the dri­est year on record since such num­bers have been kept, dat­ing back over 150 years. Less rain­fall means stunted olive oil pro­duc­tion, with few options for farm­ers when water prices remain high. This per­tains to the bulk of American olive oil pro­duc­tion, con­sid­er­ing that 90 per­cent of olives grown domes­ti­cally come from California.

This lack of rain, and the low har­vest num­bers that may fol­low stand in stark con­trast to 2012, when wide­spread drought in Europe sent EU olive oil prices soar­ing, sit­u­at­ing California grow­ers with the chance to grab mar­ket share in the heart of the Old World.

The Pacific Institute, an orga­ni­za­tion that con­ducts research on sus­tain­able alter­na­tives reported that reg­u­lated deficit irri­ga­tion, in which irri­ga­tion is applied dur­ing the most drought-sen­si­tive growth stages of a crop, can sig­nif­i­cantly reduce water use, might be appro­pri­ate for use on olive ranches.

Extremes in tem­per­a­ture, which are also grow­ing in fre­quency, pose grave risks to a olives as well. In 1998, severe cold tem­per­a­tures caused sig­nif­i­cant losses for olives in California, and was espe­cially dam­ag­ing to cit­rus fields. Olive trees can nor­mally han­dle brief cold snaps, but sub- freez­ing tem­per­a­tures that last longer than a few hours will dam­age new, small branches, and may pre­vent fruit pro­duc­tion.

The vari­abil­ity in chill­ing hours, which gar­ner less atten­tion than frost, are equally impor­tant to over­all olive vital­ity. Dennis Baldocchi, a pro­fes­sor in the Department of Environmental Science, Policy, and Management at UC Berkeley has pub­lished research indi­cat­ing that accu­mu­lated win­ter chill hours are declin­ing in the grow­ing regions of California, which affects a range of crops from olives to plums to almonds. A sub­stan­tial amount of chill­ing hours (between 32 and 45 degrees Fahrenheit) are nec­es­sary for olive flower bud devel­op­ment, which facil­i­tate the plant’s move­ment out of its veg­e­ta­tive state so fruit can be pro­duced.

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Climate does not only affect olive trees directly, but chang­ing tem­per­a­tures also influ­ences insect diver­sity and fre­quency for a given area. A recent arti­cle in the University of California’s California Agriculture jour­nal reported that ris­ing car­bon diox­ide lev­els will exac­er­bate most insect and pest prob­lems in the State. This is par­tic­u­larly rel­e­vant to the olive fly, olive’s most noto­ri­ous and costly pest, but stud­ies show that this effect may actu­ally oper­ate in a counter-intu­itive way.

The olive fly, which was first detected in the US in 1998 out­side Los Angeles, can­not tran­si­tion from egg to adult under high sum­mer tem­per­a­tures, and exist­ing adults have reduced fly­ing abil­ity dur­ing such heat. In fact, some ranch­ers in California’s Sonoma and Napa coun­ties believe that last summer’s mild tem­per­a­tures are the rea­son for increased olive fly infes­ta­tions in the region, with­out stretches of sum­mer heat to reduce the fly pop­u­la­tion. Together, these effects cre­ate a com­plex web of our chang­ing cli­mate and olive oil pro­duc­tion, whose future will require fur­ther sci­en­tific research, care­ful mon­i­tor­ing, and in the end, some rain.



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