Will irrigation be the next limit to growth?

It also indicates that the latent environmental impact of irrigated agriculture could have been seriously miscalculated.

"Policymakers and model-end users should swiftly acknowledge these uncertainties to avoid potential environmental costs", says Arnald Puy (University of Bergen, Princeton University), who has just published his findings in Geophysical Research Letters with his researcher-fellows Andrea Saltelli (University of Bergen) and Samuele Lo Piano (University of Reading).

Down-wards biased projections

Models are widely used by policy-makers to define strategies aiming at guaranteeing environmental welfare or managing climate change. If these models are inaccurate, our policies risk being biased too.

Their research suggests that projections of irrigated areas are down-wards biased because they overlooked uncertainties.

"When you design a model, there is a plethora of alternative ways of formulating it. If you chose just one way, you are ignoring these alternatives – disregarding perfectly reasonable scenarios. Previous models of irrigated areas, for instance, assumed that we perfectly know how much cropland we will have available in 2050, or how much the population will grow, or what the available volume of water will be in the future. But the truth is that we do not know with enough certainty. And previous models were designed as if we do", Puy explains. 

New strategies to ensure water safety

Their study also highlights that the potential global extension of irrigation might be twice, or in the most extreme scenario, even four times larger than what has been suggested by previous models. Arnald Puy, Samuele Lo Piano and Andrea Saltelli say that these findings imply that strategies that aim to ensure water safety or minimizing future agricultural-related greenhouse gases, for instance, should be redefined.

– Our study show that the assumption regarding the size of irrigated areas in 2050 is resting on very fragile grounds. The findings also implicate that water consumption caused by irrigation might be much larger than previously thought, and that could put severe pressure on the distribution of water across sectors, such as agriculture, industry and domestic areas. Consequently, we should include measures to anticipate and cope with water scarcity, which can end up being a lot worse than first suggested.

A demand for more adaptive solutions

The authors of the study hope that the new knowledge can be used to design strategies on water and agriculture management that are flexible enough to work both in our current situation and in a situation of an unbearable environmental pressure on water and land resources.

– Our research is showing a clear demand for more adaptive solutions in the domain of water and land management in order to better manage the uncertainties that shape the future evolution of irrigated agriculture.