Comparison of Carbon Footprints of Lettuce Cultivation Systems in the Mediterranean Area

Climate change has led to rising temperatures and increasingly extreme weather conditions, largely driven by human activity, including agriculture. The food and agriculture sector is responsible for approximately 21–37% of global greenhouse gas (GHG) emissions. In response to climate change, various innovative agricultural systems have emerged in recent decades. Among them, soilless systems represent revolutionary methods for producing large quantities of vegetables while using fewer inputs, including water, fertilizers, and pesticides. This study assesses the carbon footprint of two greenhouse-based lettuce (cv. Romana) growing systems using a cradle-to-gate life cycle assessment (LCA) approach. The first system employs an aeroponic growing method, whereas the second relies on a soil-based growing method within the greenhouse. To contextualize their environmental performance, the carbon footprints of these greenhouse cultivation systems are compared with those of the outdoor pot system. Results indicate that the highest Global Warming Potential (GWP) is associated with soil-based cultivation in the greenhouse, reaching 7.98 kg CO2eq per kilogram of fresh weight (FW) lettuce, followed by the outdoor pot system (1.72 kg CO2eq/kg), while the aeroponic system demonstrates the lowest GWP, achieving 0.98 kg CO2eq/kg. The greenhouse structure contributed 9357.93 kg CO2eq to the total GWP, representing 23% of the total impact in the aeroponic system and 22.7% in the soil-based greenhouse system. These findings suggest that soilless cultivation systems can provide a more sustainable and higher-yield alternative to soil-based methods, potentially reducing the environmental impact of vegetable production in the Mediterranean region.