Water consumption could double by 2050 in France if global warming intensifies and if current usage trends continue, due in particular to the increase in needs linked to irrigation, estimates a report from Monday. France Strategy. This report was commissioned in the fall of 2023 by the Prime Minister at the time, Elisabeth Borne, a few months after the implementation of the Water Plan intended to limit the consumption of this resource promised to become scarce due to climate change.
Already, “ in ten years, renewable fresh water, that is to say that which is renewed through the water cycle, has decreased by 14%. As a result, tensions between uses emergingemerging in certain territories and at certain times of the year », notes France Stratégie while presenting its work.
To carry out this prospective work, the organization responsible for evaluating public policies relied on three scenarios: the first, called “trend”, involves maintaining current consumption habits without changing anything. The second, called “public policies”, assumes theapplicationapplication strict restriction and adaptation measures already put in place by the government, in particular the National Low Carbon Strategy (SNBC). Finally, a third “breakthrough” scenario involves careful use of water.
She added different projections of climate warming, with dry or humid spring-summers, measuring the impact on seven sectors of activity: livestock farming, irrigation, energyenergyindustry, tertiary, residential and navigation channels.
What scenario to contain the increase in consumption?
Agriculture is the sector for which climate change will play an essential role, underlines the report: a reduction in precipitationprecipitation would generate “ an increase in demand for irrigation water if we want to maintain the same yields », exacerbated by the increase in irrigated areas, underlines Hélène Arambourou, co-author of the report.
The reference year is 2020, for which water consumption, that is to say the share of water taken and not returned to the environment, was around 5 billion cubic meters.
In the event of global warming of +2.4°C between 2041 and 2060 (one of the scenarios in the IPCCIPCC) with droughtsdroughts significant, water consumption could go up to double (+102%) between 2020 and 2050 in the “trend” scenario and increase by 72% in the “public policies” scenario, indicates the report. Only the rupture scenario would contain the increase at +10%, with sometimes strong variations depending on the region and time of year.
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Levies, particularly from industry, could stabilize (“trend”), or even decrease (“public policies” or “disruption”), due to the cessation or modernization of nuclear power plantsnuclear power plants the oldest. This drop will be mainly concentrated in the Rhône valley.
-Sobriety and conflicts of use in agriculture
But only the “disruption” scenario, characterized by energy sobriety and a less significant share of nuclear power, would lead to both a reduction in withdrawals and consumption, according to Simon Ferrière, co-author of the report.
Side agricultureagricultureby 2050, the demand for irrigation is expected to increase sharply and become the majority. And at the “ difference in energy production (which returns part of the water to natural environments once reprocessed, Editor’s noteEditor’s note), irrigation consumes the majority of water withdrawn due to plant evapotranspiration », underlines France Stratégie.
Even in the disruption scenario, consumption linked to irrigation would increase by 40%, the authors of the report explained Monday during a press briefing. And replacement reservoirs (mega-basins) will only have a limited effect in containing this increase (-6% during peak consumption).
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« Without systemic change [de l’agriculture]it seems complicated to reduce demand », explains Hélène Arambourou, who cites as levers the amplification of agroecological practices, the improvement of irrigation efficiency and regulation of the development of surfaces and crops requiring irrigation.
With this preponderance of agriculture in the withdrawals, the demand for water will also be more concentrated on the summer months which are traditionally the hottest and where the resource is constrained, notes the organization which plans to study in a future report the tensions and conflicts of use that this could generate.
The territories most concerned are those already highly irrigated such as the South-West, the landslands around the Marais Poitevin or the Charente, in which there are already conflicts of use at certain times of the year.
