Modelling the influence of atmospheric CO₂ on irrigation demand in vineyards of the Sardinia region

¹ Department of Agriculture, University of Sassari, Viale Italia, 39, 07100 Sassari, Italy
² CMCC Foundation – Euro-Mediterranean Centre on Climate Change, Italy
³ Land and Water Management Department, IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands
⁴ UMR 1114 EMMAH INRAE/AU, Avignon, France
⁵ Land, Air and Water Resources Department, University of California, One Shields Ave., Davis, CA 95616, USA
⁶ National Biodiversity Future Center S.c.a.r.l., (NBFC), Palazzo Steri, Piazza Marina 61, Palermo, 90133, Italy

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The Mediterranean countries are anticipated to face considerable warming and drying with uncertain precipitation patterns further exacerbating the vulnerability of semi-arid regions, like Sardinia. Sardinia’s vineyards, crucial to the local economy and cultural heritage, are increasingly threatened by climate change risks, particularly affecting physiological processes, which can compromise grapeyields and wine quality. The research aims to assess the impact of climate change on evapotranspiration demand in Sardinian vineyards, while keeping into account mitigating effects (e.g. reduced stomatal conductance) due to atmospheric CO₂ concentration increase. This study utilizes the Simulation of Evapotranspiration of Applied Water (SIMETAW_GIS) model to evaluate the impact of climate change on water demand of vineyards in Sardinia region, Italy. The research leverages high-resolution climate future projections to evaluate how varying climate conditions will affect the water demand of vineyardsunder three Representative Concentration Pathways (RCP2.6; RCP4.5; RCP8.5). Additionally, the analysis addresses the uncertainty associated with rising atmospheric CO₂ concentration, evaluating both the direct impact of CO₂ fertilization and without these effects. Increasing CO₂ can improve water use efficiency, partially mitigating negative impacts following rising temperatures and uncertain precipitation patterns. The results revealed that grapevine water demand is projected to rise by 5%-7% withCO₂fert and 7%-10% withCO₂constreflecting a relative percentage change between the historical period (1976-2005) and mid-century (2036-2065) under future projection (RCP2.6; RCP4.5; RCP8.5). The inclusion of CO₂ effects significantly alters canopy resistance in the reference evapotranspiration (ET₀) estimation, thus limiting vegetation water demand. The research highlights the importance of integrating the CO₂ effects into crop water demand assessment and underscores the necessity for adaptive irrigation strategies to the resilience and sustainability of Sardinian vineyards amidst rapidly evolving climate conditions.