According to an article published in the journal of Nature Communications, Colorado State University researchers found that irrigation pumping on U.S. farmland accounts for approximately 16% (~12.64 million metric tonnes) of all greenhouse gas emissions from energy use in agriculture.
“Irrigation is a super promising adaptation strategy for climate change,” said Avery Driscoll, a doctoral student in CSU’s Department of Soil and Crop Sciences and the paper’s lead author. “But we knew very little about irrigation’s impact on greenhouse gas emissions.”
The Study
The research was conducted over two years by Driscoll and her co-authors, and analyzed various data sets to estimate irrigation energy emissions for all 50 states. Groundwater pumping was found to contribute significantly to emissions, contributing 85%, despite accounting for less than half of irrigation water use. According to the study, the rate of emissions from groundwater pumping was 5 times greater than for surface water. The depth of groundwater extraction also impacted emissions, with higher emissions associated with deeper wells.
The research estimated emissions for 12 major irrigated crops, identifying corn grain as the highest emitter and soybeans as the lowest. Understanding the emissions impact of irrigation can help the agricultural industry address climate change challenges more effectively, especially as irrigation patterns shift due to water scarcity and climate variability.
The study also revealed spatial variations in emissions, with states like Texas, Nebraska, and California producing the highest emissions due to irrigation, accounting for 46% of irrigation-related greenhouse gas emissions. But, the study also found that electric pumps were the most widely used, and produced lower average emissions than other types of pumps. Electric pumps were identified as key to reducing emissions, given efforts to decarbonize the electrical grid.
“Irrigation expansion for climate change adaptation is not going to be random,” Driscoll said. “We’re seeing contractions in the Western U.S., where we have these water scarcity limitations, and are seeing expansion in the Eastern U.S., where we’re seeing more frequent and intense drought, incentivizing the adoption of irrigation because they still have a water supply.”
The Problem
So what's next? The study finds that electric (solar powered) pumps are the key to reducing emissions, yet policies like NEM 3.0 are making it increasingly difficult to afford solar on farms in California. Last year, California’s electricity system changed the net metering system from NEM 2.0 to NEM 3.0, which features a 75% reduction in export rates (the value of excess electricity pushed onto the grid by solar systems), thereby reducing the overall savings and increasing the payback period of solar.
Unless California can find a way to finally advocate for famers and encourage the electricity companies to incentivize and compensate farmers to upgrade their irrigation systems, this study remains merely academic. Real change requires actionable policies and financial support to facilitate the transition to more sustainable practices. Without such initiatives, the future of rural economies and our national food security remains unsteady.
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