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CMIP6-Projected Mid-Season Heat Stress and Adaptation Potential for Open-Field Tomato Production in Spain and Morocco

Connell, Chelsea Ann LU (2026) NGEK11 20261
Department of Earth and Environmental Sciences (MGeo)
Abstract
Open-field tomato (Solanum lycopersicum L.) production in the western Mediterranean is increasingly exposed to temperatures exceeding reproductive thresholds. Existing projections focus on the largest processing regions, the United States, Italy, and China, and omit the two producers that anchor Mediterranean supply on either side of the Strait of Gibraltar. Neither Spain, the region's second-largest processing-tomato producer, nor Morocco, the European Union's leading external supplier of fresh tomato, has been assessed at either the site or national scale. This thesis quantified projected heat stress at six sites, three in Spain and three in Morocco, and across both countries at 0.25°, using daily maximum and minimum temperatures from... (More)
Open-field tomato (Solanum lycopersicum L.) production in the western Mediterranean is increasingly exposed to temperatures exceeding reproductive thresholds. Existing projections focus on the largest processing regions, the United States, Italy, and China, and omit the two producers that anchor Mediterranean supply on either side of the Strait of Gibraltar. Neither Spain, the region's second-largest processing-tomato producer, nor Morocco, the European Union's leading external supplier of fresh tomato, has been assessed at either the site or national scale. This thesis quantified projected heat stress at six sites, three in Spain and three in Morocco, and across both countries at 0.25°, using daily maximum and minimum temperatures from six general circulation models in the NEX-GDDP-CMIP6 ensemble, bias-corrected against AgERA5. Exposure was assessed for a 1985–2014 baseline and, under intermediate (SSP2-4.5) and very high-emission (SSP5-8.5) pathways, for 2030–2059 and 2070–2099. Four threshold-based metrics were computed for the mid-season reproductive window: chronic-stress days, acute-stress days, sustained-stress events, and cumulative degree-days. Adaptation potential was evaluated across four transplant dates and two seedling ages. Heat stress intensified at all sites under both pathways. Under SSP5-8.5 by 2070–2099, chronic-stress days increased from 0.4–7.7 to 11.6–22.3 per year, acute-stress days from at most 1.0 to 5–10 per year, sustained-stress events from 0.03–0.96 to 1.28–1.70 per year, and cumulative degree-days more than tripled. Exposure was greater farther from the coast and lower at higher elevations, with the Moroccan interior emerging as the principal hotspot. Advancing transplanting from June to March was 3–4 times as effective as doubling seedling age, a ratio that reflects the tested ranges rather than the effect per day of calendar shift. The lowest-exposure configuration (March 1 transplant with 60-day seedlings) did not significantly exceed baseline stress in 88 of 96 comparisons, and the eight exceedances all occurred under SSP5-8.5 by 2070–2099. Calendar adjustment is the first adaptation measure through mid-century, but sustaining production at the most exposed sites under very high emissions by the end of the century will require heat-tolerant cultivars or protected cultivation. The hotspot maps indicate where such measures are needed first. (Less)
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author
Connell, Chelsea Ann LU
supervisor
organization
alternative title
CMIP6-projicerad värmestress under mittsäsongen och anpassningspotential för frilandsodling av tomat i Spanien och Marocko
course
NGEK11 20261
year
type
M2 - Bachelor Degree
subject
keywords
agroclimatic indices, climate change adaptation, crop calendar, processing tomato, statistical downscaling
language
English
id
9252066
date added to LUP
2026-10-01 09:26:21
date last changed
2026-10-01 09:26:21
@misc{9252066,
  abstract     = {{Open-field tomato (Solanum lycopersicum L.) production in the western Mediterranean is increasingly exposed to temperatures exceeding reproductive thresholds. Existing projections focus on the largest processing regions, the United States, Italy, and China, and omit the two producers that anchor Mediterranean supply on either side of the Strait of Gibraltar. Neither Spain, the region's second-largest processing-tomato producer, nor Morocco, the European Union's leading external supplier of fresh tomato, has been assessed at either the site or national scale. This thesis quantified projected heat stress at six sites, three in Spain and three in Morocco, and across both countries at 0.25°, using daily maximum and minimum temperatures from six general circulation models in the NEX-GDDP-CMIP6 ensemble, bias-corrected against AgERA5. Exposure was assessed for a 1985–2014 baseline and, under intermediate (SSP2-4.5) and very high-emission (SSP5-8.5) pathways, for 2030–2059 and 2070–2099. Four threshold-based metrics were computed for the mid-season reproductive window: chronic-stress days, acute-stress days, sustained-stress events, and cumulative degree-days. Adaptation potential was evaluated across four transplant dates and two seedling ages. Heat stress intensified at all sites under both pathways. Under SSP5-8.5 by 2070–2099, chronic-stress days increased from 0.4–7.7 to 11.6–22.3 per year, acute-stress days from at most 1.0 to 5–10 per year, sustained-stress events from 0.03–0.96 to 1.28–1.70 per year, and cumulative degree-days more than tripled. Exposure was greater farther from the coast and lower at higher elevations, with the Moroccan interior emerging as the principal hotspot. Advancing transplanting from June to March was 3–4 times as effective as doubling seedling age, a ratio that reflects the tested ranges rather than the effect per day of calendar shift. The lowest-exposure configuration (March 1 transplant with 60-day seedlings) did not significantly exceed baseline stress in 88 of 96 comparisons, and the eight exceedances all occurred under SSP5-8.5 by 2070–2099. Calendar adjustment is the first adaptation measure through mid-century, but sustaining production at the most exposed sites under very high emissions by the end of the century will require heat-tolerant cultivars or protected cultivation. The hotspot maps indicate where such measures are needed first.}},
  author       = {{Connell, Chelsea Ann}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{CMIP6-Projected Mid-Season Heat Stress and Adaptation Potential for Open-Field Tomato Production in Spain and Morocco}},
  year         = {{2026}},
}