Environment
THE amount of water humans extract from underground is set to peak within the next three decades as pumping depletes accessible stores. This could reshape the food and water systems that serve at least half the world’s population.
Between 1960 and 2010, global groundwater extraction increased by more than 50 per cent, largely to irrigate crops. Today, one-fifth of all food is produced using groundwater. Much of this water is extracted from aquifers faster than they refill, decreasing water levels. This causes the land to sink, means contaminants build up in the remaining water and harms ecosystems fed by the aquifers. It also increases the cost of extraction, because wells must be drilled deeper and water pumps require more energy.
Previous studies projected this groundwater extraction would rise indefinitely, but they “did not have the human feedback in there”, says Hassan Niazi at Pacific Northwest National Laboratory in Washington state.
Niazi and his colleagues have now projected how dropping water levels and rising pumping costs could affect extraction in the world’s major water basins this century. They used a model that incorporates relationships between groundwater extraction, economic development, energy systems and climate change.
20% Amount of the world’s food produced using groundwater
The researchers modelled 900 scenarios to capture a range of possible futures.
On average across scenarios, they found that the volume of groundwater extracted peaked in about 2050 at 625 cubic kilometres of water, about twice as much as today. By century’s end, extraction declined to near present-day level. The peak’s timing and magnitude varied across scenarios, but nearly all forecasted a peak before 2100 (Nature Sustainability, doi.org/mw2g).
Some regions may face quicker declines. In most scenarios, extraction peaked before 2030 in 10 per cent of studied water basins, including in large areas of India, Pakistan and China. Extraction in some basins seems t
