Plate Nº 13 · recorded October 10, 2026
Earth & ClimateReported finding
U.S. Irrigation Avoids 6.86 Gigatons of Emissions via Spared Land
A PNAS analysis finds U.S. irrigation spares 6.86 gigatons of greenhouse gases by preventing farmland expansion — 363 times the emissions irrigation produces directly. The benefit could grow as pumps electrify.
By Nathan Brooks3 min read673 words
In brief
- Irrigation prevents an estimated 6.86 gigatons of greenhouse gas emissions by sparing natural land from farm conversion.
- That avoided figure is roughly 363 times current annual U.S. irrigation emissions.
- It exceeds total U.S. greenhouse gas emissions in 2024 (5.91 gigatons) and equals about 13% of global emissions that year.
- The study was published September 14, 2026 in Proceedings of the National Academy of Sciences by a Colorado State University-led team.
- Agricultural land use and land conversion account for nearly a quarter of global greenhouse gas emissions, the authors note.
U.S. crop irrigation prevents an estimated 6.86 gigatons of greenhouse gas emissions by sparing natural land from farm conversion — about 363 years of emissions from irrigation itself, according to research published September 14 in Proceedings of the National Academy of Sciences.
The analysis reframes irrigation as a net climate positive. Lead author Avery Driscoll did the work as a Colorado State University Ph.D. student; she is now a postdoctoral researcher at Purdue University. The team compared direct emissions from pumps and soils with the indirect benefit of higher yields per acre.
How does irrigation prevent so much emissions?
Higher yields mean less land in production. Researchers first measured yield gains county by county, using agricultural survey data and a machine learning model.
They then ran a global economic model of farming, consumption, and trade to simulate a U.S. without irrigation. The model flagged where new farmland would appear and how much carbon that land stores in vegetation and soils.
Converting forests or grasslands releases that carbon. Agricultural land use drives nearly a quarter of global greenhouse gas emissions, the study notes.
What do the numbers show?
Avoided conversion saves 6.86 gigatons of greenhouse gases. That exceeds total U.S. emissions in 2024, which reached 5.91 gigatons, and equals roughly 13% of global emissions that year.
"It was clear from this work that irrigation has a net positive effect on emissions," Driscoll said. "The avoided emissions from reductions in indirect land-use change were much greater than the direct emissions, and that could decline further with electrification."
Where do irrigation's own emissions come from?
Most direct emissions come from energy used to move water. Pumps run on fossil fuels for on-farm irrigation and interbasin transfers. Smaller sources include nitrous oxide from microbial respiration in wet soils and dissolved carbon dioxide that escapes from sprayed groundwater.
Electrifying pumps could shrink the footprint quickly, especially as the U.S. grid decarbonizes. The authors suggest pump-electrification incentives for climate-smart agriculture programs.
What's missing from the analysis?
The team did not count several farm-level emission sources:
- Nitrogen fertilizer application
- Methane from livestock
Both are significant. Their absence means the avoided-emissions figure, though large, sits beside an incomplete food-system tally.
How do the trade-offs play out?
Climate math is only one slice of the picture, said co-author Nathan Mueller, a CSU associate professor in Ecosystem Science and Sustainability and Soil and Crop Sciences.
"We're able to show this large benefit of U.S. irrigation to greenhouse gas emissions from the food system," Mueller said. "Yet, when we talk about water use, particularly in the western U.S., there are trade-offs with every use and trade-offs beyond food and beyond greenhouse gas emissions."
That tension shows up close to home for a farmer quoted in the study. CSU alumnus Alex Brown's family has worked the same land in Yuma County, Colorado, for 120 years.
"We need irrigation to fulfill our needs and our duty to continue to feed the world," Brown said. Without it, he added, farmers would plow fragile pasture for crops and lean on unreliable rainfall.
Why does this framing matter for climate policy?
Policies aimed at cutting food-system emissions must capture direct on-farm sources and indirect land-use effects, the researchers argue. Identifying where to electrify pumps or raise yields lets policymakers pursue local cuts without sacrificing the global benefit of more food on less land.
"Irrigation is a powerful adaptation strategy," Driscoll added. "It increases productivity; it increases resilience to heat and drought stress... understanding how those two challenges interact with one another is a priority."
The National Science Foundation and the AI Institute for Land, Economy, Agriculture & Forestry funded the work, with U.S. Department of Agriculture support. Collaborators included University of Minnesota economist Justin Johnson, Joey Blumberg of the U.S. Forest Service Rocky Mountain Research Station, Alison King of the University of Maine, and Seth Spawn-Lee of The Nature Conservancy.
via source.colostate.edu (Original)
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