Burgeoning demand for food to feed the world's swelling population, coupled with increased use of biomass as fuel is putting a serious strain on global water reserves, experts said
"If we look at how much more water we will need for food and how much more for biomass for energy going forward ... it is quite worrying," said Jan Lundqvist, who heads the scientific programme at the Stockholm International Water Institute (SIWI).
Global food needs are expected to roughly double by 2050, at the same time as climate change and dwindling oil reserves are pressuring countries to set aside ever more land for producing biomass to replace greenhouse gas-emitting fossil fuels.
These parallel global trends risk colliding with "the water-constrained biophysical reality of the planet," according to SIWI, which hosted the World Water Week in the Swedish capital last week.
"Almost every increase in water used in agriculture will affect water availability for other uses, including that needed to keep ecosystems healthy and resilient in the face of change and perturbation," the institute said in a recent study.
According to Lundqvist, the global population today uses around 4,500 cubic kilometres of water each year to cover all water needs, including for agricultural irrigation, urban use and for energy production. While that is below the level of what is considered environmentally irresponsible, he stressed that future needs could rapidly push water use to dangerous levels.
"It might be environmentally reasonable to withdraw maybe 6,000 (cubic kilometres), but if we withdraw more water it would be at a very high environmental cost, because we need water to flush the system and for different ecosystem services," he said.
"It is simply not advisable." According to SIWI project director Jakob Granit, recent studies indicate that "by 2030, the same amount of energy that we produce today with fossil fuels will have to come from biomass."
At the same time, scientists predict we will only be able to "meet food demands by 2050 if we have a much more efficient use of water ... That does not include the water we need for all that biomass," he told AFP.
In addition to questioning whether it is realistic to expect biomass to cover a large share of our energy needs in the future, the best way to address the problem of shrinking water reserves is to better manage water and land use, experts say.
According to Lundqvist, there is a dire need to shift the world's focus away from irrigation systems, which are putting so much pressure on rivers, lakes and groundwater. "We are at the end of the road when it comes to irrigation, because all the water available in rivers and so on has already been now more or less used up," he said, insisting that much more attention must be paid to the potential of rainfall.
"In a large part of Africa, if you look at the total rainfall throughout the year the amount is usually enough ... to grow many crops," he said. "If you can capture that rainfall, and store it as soil moisture or in local dams, it would be possible to significantly increase food production in these areas," he added.
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