Adapting agriculture to climate change via sustainable irrigation: biophysical potentials and feedbacks

Abstract

Irrigated agriculture accounts for ∼90% of anthropogenic freshwater consumption, is deployed on 22% of cultivated land, and provides 40% of global food production. Expanding irrigation onto currently underperforming rainfed croplands is crucial to meet future global food demand without further agricultural expansion and associated encroachment of natural ecosystems. Establishing irrigation is also a potential climate adaptation solution to alleviate heat- and water-stress to crops and reduce climate variability and extremes. Despite irrigation being one of the land management practices with the largest environmental and hydroclimatic impacts, the role of irrigation to adapt agriculture to climate change and achieve global sustainability goals has just started to be quantified. This study reviews biophysical opportunities and feedbacks of ‘sustainable irrigation’. I describe the concept of sustainable irrigation expansion—where there are opportunities to increase agricultural productivity over currently water-limited rainfed croplands by adopting irrigation practices that do not deplete freshwater stocks and impair aquatic ecosystems. Expanding sustainable irrigation may avert agricultural expansion but create additional externalities that are often neglected. This review highlights major gaps in the analysis and understanding on the role of sustainable irrigation expansion to adapt agriculture to climate change. This study reviews the implications of a potential sustainable irrigation expansion on (a) global food security, (b) hydroclimatic conditions, (c) water quality, (d) soil salinization, (e) water storage infrastructure, and (f) energy use. These implications help to explain the challenges of achieving sustainability in irrigated agriculture and thus also point toward solutions and future research needs.

Future Food Security in Africa Under Climate Change

“…Here, a yield gap is defined as the difference between water-limited potential yield and the actual yield that a farmer currently achieves on a cropland (Lobell et al, 2009;Rosa et al, 2018). Narrowing or closing yield gaps through sustainable irrigation expansion is an agricultural intensification strategy to boost crop production without threatening biodiversity-rich ecosystems through expansion of agricultural croplands (Beltran-Peña et al, 2020;Rosa, 2022;Van Ittersum et al, 2013). This study considers a target yield gap closure of 80% as the feasible limit proposed by Van Ittersum et al (2016).…”

Accounting for socioeconomic constraints in sustainable irrigation expansion assessments

“…At the same time, climate change has and is expected to change rainfall patterns and further exacerbate existing water-and heat-stress for rain-fed agricultural systems (Mbow et al 2019, Valipour et al 2021. Irrigation expansion, despite its documented environmental and hydroclimatic implications (Foster et al 2018, plays an essential part in the portfolio of response options by offering the possibility to increase crop yields via the maintenance of reliable water supply, while potentially also alleviating some of the negative impacts of temperature extremes on crops (Thiery et al 2017, Rosa et al 2020a, Droppers et al 2021, Caretta et al 2022, Rosa 2022. Irrigation will also have an important role in the sustainable intensification of agriculture, an effort to halt agricultural expansion by increasing crop yields in underperforming cultivated lands (Mueller et al 2012, Rosa et al 2018, Droppers et al 2021.…”

“…governance or income) tend to be overlooked in quantitative assessments of potential future irrigation deployment, including climate impact models, thereby assuming optimal or maximum possible irrigation and thus potentially overstating its benefits (Holman et al 2019). Other analyses have indeed argued that, apart from biophysical or technological factors, irrigation is largely limited by institutional and economic capacity (Rosa et al 2020a, Rosa 2022. The lack of irrigation due to limited institutional and economic capacity instead of hydrologic constraints is referred to as economic water scarcity (Rosa et al 2020a, Rosa 2022.…”

“…Other analyses have indeed argued that, apart from biophysical or technological factors, irrigation is largely limited by institutional and economic capacity (Rosa et al 2020a, Rosa 2022. The lack of irrigation due to limited institutional and economic capacity instead of hydrologic constraints is referred to as economic water scarcity (Rosa et al 2020a, Rosa 2022. Social, political, and economic factors are considered to be the most crucial factors influencing future sustainable irrigation development (Higginbottom et al 2021).…”

The spatiotemporal trajectory of US agricultural irrigation withdrawal during 1981–2015

“…As the largest water consumption sector, irrigation has enhanced food and biofuel production over the world. The sustainability of irrigation is facing substantial challenges from current and future renewable water availability, freshwater stock depletion, environmental flow deterioration and water right conflicts (Qin et al 2019, Rosa 2022. While water supply is stressed by climate variability and extremes, there have been increasing demands within the agriculture sector due to irrigated cropland expansion as well as in other water using sectors with competing demands (Döll 2002, Döll andSiebert 2002).…”