Irrigation accounts for more than 70% of global freshwater withdrawals, yet it remains one of the least well-characterised human influences in climate models. New research under ESA's Climate Change Initiative (CCI) takes a significant step towards closing that gap.
The CCI's Anthropogenic Water Use project has developed a long-term dataset collection of monthly irrigation water use estimates at 0.25 degrees spatial resolution, covering four major irrigated regions: the contiguous United States, India, the Murray-Darling Basin in Australia, and the Ebro Basin in Spain. The datasets span up to two decades and were produced using three distinct satellite-based methods, all drawing on ESA's soil moisture climate data records.
The comparison of methods is itself a key contribution. By testing three independent approaches against the same regions, the study provides a transparent picture of where satellite-based irrigation estimates agree, and where uncertainties remain.
"The work marks an important step towards an Earth Observation-based climate data record of irrigation water use, providing long-term, spatially explicit estimates that can help climate models better account for human activities such as irrigation," says Jacopo Dari, Science Leader of the project at the University of Perugia (Italy).
The datasets are openly available and lay the groundwork for a future global climate data record of irrigation – a variable that shapes water cycles, food security, and regional climate alike.
