Carbon and water footprint tradeoffs in fresh tomato production

There is growing interest in carbon footprints of products but for horticulture water use can also be important, hence we studied both for fresh tomatoes supplied to the Sydney market. Carbon and water footprints for each kg of fresh tomato supplied to Sydney depend on the season and the type of production system (ranging from 0.39 to 1.97 kg CO2e; 5 to 53 L). Energy use of the systems was also reported which ranged from 6.16 to 27.42 MJ for each kg of fresh tomato supplied to Sydney. Tradeoffs exist within studied production systems such that a system which had higher carbon footprint had lower water footprint; this complicates setting priorities for overall environmental improvement. To address this limitation, life cycle impacts of greenhouse gas (GHG) emissions and water use were subsequently modelled using endpoint indicators and compared. The results indicated that in all cases the climate change impacts were most important representing 84-96% of the combined scores on damages to the environment. As such the vegetable industry's priority to reduce GHG emissions is confirmed. In case of field production, transportation of tomatoes to market was the hotspot in carbon footprint, while for the medium and high technology greenhouses it was artificial heating. Although the results indicated priority to reduce carbon footprint, further development and harmonisation of LCA impact assessment models for water use at the endpoint level is considered essential.