Study: Climate Change Is Making Droughts More Frequent and Severe

Widespread droughts occur­ring simul­ta­ne­ously in dif­fer­ent regions of the planet may be part of a wors­en­ing trend that will exac­er­bate water inse­cu­rity and hurt agri­cul­ture, accord­ing to a new study.

The research pub­lished in Nature Climate Change con­cluded that extreme, repeated co-occur­ring (also known as com­pound) drought events pose a sub­stan­tial threat to increas­ingly inter­con­nected socio-eco­nomic sys­tems.

A sec­ond study pub­lished in the same jour­nal high­lighted how the west­ern United States is expe­ri­enc­ing a megadrought, the likes of which have not been seen in the last 1,200 years.

By exam­in­ing trees and other remains pre­served in Native American arche­o­log­i­cal sites, researchers com­pared the cur­rent 22-year dry period to what they believe hap­pened in 800 C.E. Even an extreme multi-year event recorded in 1500 does not match the cur­rent sit­u­a­tion.

Both stud­ies found that human activ­i­ties and the depen­dency on fos­sil fuels are sig­nif­i­cant causes of drought prob­a­bil­ity and sever­ity.

In the most recent Olive Oil Times sur­vey, nearly one-third of pro­duc­ers said droughts had impacted their 2021 har­vest sea­son.

According to the west­ern United States study, which also mea­sured the pro­gres­sive loss of soil mois­ture dur­ing the worst his­toric pro­longed droughts, human con­tri­bu­tion is respon­si­ble for 72 per­cent of megadrought’s like­li­ness and sever­ity.

Compared with the 20^th cen­tury, the instances of co-occur­ring droughts in the 21^st cen­tury also increased sub­stan­tially.

“Our analy­sis shows an increased prob­a­bil­ity of expe­ri­enc­ing simul­ta­ne­ous droughts across mul­ti­ple regions by the mid and late 21^st cen­tury rel­a­tive to the late 20^th cen­tury, with con­tin­u­ous fos­sil fuel depen­dence,” Jitendra Singh and Deepti Singh, envi­ron­men­tal researchers at Washington State University, told Olive Oil Times.

“The risk of simul­ta­ne­ous droughts is expected to increase by about 40 per­cent and 60 per­cent by the mid and late 21^st cen­tury, respec­tively,” they added.

The study focused on the con­nec­tions among con­tin­ued fos­sil-fuel depen­dency, increas­ing global tem­per­a­tures, El Niño and La Niña phe­nom­ena (also known as ENSO) and droughts.

The sce­nario is known as RCP 8.5 (“busi­ness as usual”) and accounts for an increase in aver­age global tem­per­a­tures of more than 4.5 ºC by the end of the 21^st cen­tury.

“As shown in our study, a robust increase in simul­ta­ne­ous droughts under a high emis­sion sce­nario can pose a seri­ous threat to global food secu­rity and water avail­abil­ity in a future warmer cli­mate,” Singh and Singh said.

According to the sci­en­tists, cur­rent simul­ta­ne­ous drought events are dri­ven by ENSO events in almost two cases out of three. They warned that the cur­rent trend toward future warm­ing might amplify ENSO events’ impact on such droughts.

“Based on the sim­u­la­tions we use, the like­li­hood of El Niño and La Niña events is pro­jected to increase as well,” Singh and Singh said. ​“So they are likely to occur more often, con­tribut­ing to the large increase in the risk of simul­ta­ne­ous droughts.”

Central North America, Central America and the Amazon are more likely to expe­ri­ence drought in the future com­pared to East and South Asia, the researchers noted.

“Such regional changes in drought con­di­tions are asso­ci­ated with changes in pre­cip­i­ta­tion and evap­o­tran­spi­ra­tion char­ac­ter­is­tics,” Singh and Singh said.

This is not good news for farm­ers or the pub­lic at dif­fer­ent lat­i­tudes. In this sce­nario, researchers found that the increased prob­a­bil­ity and sever­ity of co-occur­ring droughts cause a many-fold increase in agri­cul­tural areas and peo­ple affected.

The paper focuses on the global food net­work and its com­plex­ity, hint­ing how co-occur­ring droughts in just a few highly rel­e­vant food-pro­duc­ing areas could pro­voke severe con­se­quences for food secu­rity and prices, espe­cially in socio-eco­nom­i­cally vul­ner­a­ble regions.

The researchers found that about 700,000 square kilo­me­ters – an area larger than Afghanistan – is expected to expe­ri­ence drought each year, rep­re­sent­ing a 10-fold increase over the late 20^th cen­tury.

Recent drought events exam­ined by the researchers include those from 2005 to 2007 through­out many regions.

The researchers said these exam­ples ​“caused the total grain pro­duc­tion to drop by 40 mil­lion met­ric tons [below] the require­ment, which con­tributed to high corn prices in 2008.”

“Similarly, grain pro­duc­tion dropped sub­stan­tially due to wide­spread drought across Africa and South Asia in 1982 to 1984, which was declared as a famine in Ethiopia as it affected more than seven mil­lion peo­ple,” they added.

The study did not specif­i­cally focus on the Mediterranean basin. However, a multi-year drought is wors­en­ing in sev­eral coun­tries in the region, which is respon­si­ble for more than 95 per­cent of global olive oil pro­duc­tion.

The sci­en­tists spec­i­fied that reduc­ing fos­sil fuel depen­dency and focus­ing on sus­tain­abil­ity might help mit­i­gate the impact of cli­mate change and sup­port adap­ta­tion.

“The good news is that the RCP 8.5 tra­jec­tory is becom­ing less likely than pre­vi­ously imag­ined as we progress towards tran­si­tion­ing to cleaner energy sources,” the researchers said.

According to the sci­en­tists, another road to adap­ta­tion is devel­op­ing pre­dic­tive sys­tems that offer timely warn­ings about com­pound drought events and their impacts on agri­cul­ture and pop­u­la­tion.

Those pre­dic­tions ​“can help soci­ety develop plans and efforts to min­i­mize eco­nomic losses and reduce human suf­fer­ing from such cli­mate-dri­ven dis­as­ters,” the researchers said.

“Additionally, water-effi­cient irri­ga­tion tech­nol­ogy, crop insur­ance, bal­anced man­age­ment of land and water resources, a shift toward cli­mate-resilient agri­cul­ture sys­tems and insti­tu­tional capac­ity build­ing across the coun­tries and stake­hold­ers can be help­ful to min­i­mize the impacts of simul­ta­ne­ous droughts,” they added.

The next step in the research will be to under­stand how such large-scale drought can affect the global food secu­rity (e.g., agri­cul­tural pro­duc­tions) and food trade net­work.

“Also, we aim to under­stand how global food reserves capac­ity to cope with the impacts of future large-scale droughts,” the researchers con­cluded.