Impact of changes in mean and extreme temperatures caused by climate change on olive flowering in southern Spain

Abstract

Due to the severe increase projected in future temperatures and the great economic and social importance of olive growing for vast agricultural areas in the Mediterranean Basin, accurate climate change impact assessment on olive orchards is required. The aim of this study is to assess the flowering date and the impact of mean and extreme temperature events on olive flowering in southern Spain under baseline and future climate conditions. To that end, experimental data were obtained from ten olive genotypes: six well‐known olive cultivars in the region, one cultivar, ‘Chiquitita’, obtained via conventional breeding, and three wild olives from the Canary Islands. A site‐specific model calibration was conducted resulting in satisfactory performance with an average error of 2 days for flowering date estimation under baseline and future climate conditions, and a RMSE equal to 5.5 days in the validation process. The outputs from 12 regional climate models from the ENSEMBLES European project with a bias correction in temperature and precipitation were used. Results showed an advance in the olive flowering dates of about 17 days at the end of the 21st century compared with the baseline period (1981–2010), and an increase in the frequency of extreme events around the flowering period. A spatial analysis of results identified the areas in southern Spain that are most vulnerable to climate change impact caused by the lack of chilling hours accumulation (areas located on the Atlantic coast and the south‐eastern coast) and by the occurrence of high temperatures during the flowering period (areas located in the north and north‐eastern areas of the Andalusian region).

Chilling accumulation in fruit trees in Spain under climate change

“…However, the coarse horizontal resolution of GCMs (typically 100-200 km) is a significant limiting factor. Due to the increasing demand of policymakers and end users for regionalised projections, the Coordinated Regional Climate Downscaling Experiment (CORDEX) initiative has recently been created (Giorgi and Gutowski, 2015). CORDEX EUR-11 is based on regional climate model (RCM) outputs and provides regionalised projections of key atmospheric variables at 0.11 • resolution (∼ 12 km) over Europe among other regions.…”

Chilling accumulation in temperate fruit trees in Spain under climate change

“…Olesen et al, 2007). For olive trees, previous studies indicate that the lack of knowledge on crop chilling requirements may introduce much more uncertainty than climate projections (Gabaldón-Leal et al, 2017). In any case, according to the validation process, the highresolution bias-adjusted CORDEX data provide temperature values with adequate quality for this particular application.…”

“…In fact, in absence of significant mitigation measures, global warming is likely to reach 1.5ºC between 2030 and 2052 compared to pre-industrial annual mean global temperature levels (IPCC, 2018). In this respect, several researchers (Campoy et al, 2011;Luedeling, 2012;Gabaldón-Leal et al, 2017) have pointed out that under this warming scenario, the fulfilment of chilling requirements for some crops and varieties is likely to be compromised. To develop suitable adaptation strategies for both the short and long term, reliable projections of chilling units under different emission scenarios or Representative Concentration Pathways (RCPs, van Vuuren et al, 2011) are needed.…”

Grapevine Potassium Nutrition and Fruit Quality in the Context of Climate Change

“…In sweet orange (Citrus sinensis) and clementine (Citrus clementina) sugar content increases and fruit acidity decreases (Albrigo and Galán Saúco, 2004;Cercós et al, 2006). During flowering, high temperatures can have a deleterious impact on olive production (Gabaldón-Leal et al, 2017). Altogether, understanding the underlying mechanisms to face to the climate change is now an important challenge for fruit production.…”