Main Research Findings

Analysis has shown that the use of irrigation in U.S. agriculture helps increase food production without the need to expand farmland at the expense of natural landscapes. This approach allows for the preservation of ecosystems and reduces greenhouse gas emissions associated with converting natural areas into agricultural land.

Irrigation Efficiency and Greenhouse Gas Emissions

Irrigation boosts crop yields, enabling the same amount of food to be produced on less land. If irrigation were discontinued across the U.S., compensating for the resulting drop in food production would require expanding farmland, which would lead to greenhouse gas emissions 363 times greater than the current emissions from irrigation itself. By preserving land through irrigation, emissions equivalent to 363 years of the country’s current annual irrigation-related greenhouse gas output are avoided.

The Importance of Preserving Natural Lands

Natural ecosystems store significant amounts of carbon in vegetation and soils. When forests, grasslands, and other landscapes are converted to farmland, some of this carbon is released into the atmosphere. Globally, land use for food, fiber, and fuel production accounts for nearly a quarter of greenhouse gas emissions, highlighting the importance of using agricultural land efficiently to reduce emissions.

Sources of Irrigation Emissions and Reduction Strategies

The main source of greenhouse gas emissions from irrigation is the energy required to pump water. Pumps powered by fossil fuels produce emissions, but switching to electric pumps and decarbonizing the power grid can significantly reduce this impact. Incentives for agricultural electrification are being considered in the development of “smart” farming programs.

Comparing Direct and Indirect Emissions

Previous studies focused on direct emissions from irrigation, including nitrous oxide and dissolved carbon dioxide from groundwater. This new analysis is the first to compare these emissions with the indirect climate benefits gained by reducing the need to convert additional land for agriculture.

The Scale of Prevented Emissions

Calculations show that irrigation prevents approximately 6.86 gigatons of greenhouse gas emissions by preserving natural lands. This figure exceeds all U.S. greenhouse gas emissions in 2024 (5.91 gigatons) and represents about 13% of global emissions for the same period.

Modeling a No-Irrigation Scenario

To assess the impact of irrigation on land preservation, researchers used agricultural data and machine learning models to determine how irrigation increases yields in different U.S. counties. A global economic model that accounts for production, consumption, and international trade was then used to simulate how agriculture would change if irrigation were completely eliminated. These results were combined with maps of carbon stocks in vegetation and soils to estimate potential greenhouse gas emissions.

Limitations of the Analysis

The study did not account for emissions from other types of agricultural activity, such as the application of nitrogen fertilizers or methane production from livestock.

Water Resources and Trade-Offs

Balancing water use between agriculture, communities, and ecosystems is especially important in the western U.S., where much of farming depends on irrigation. Regional water resources must meet not only farm needs but also other demands, so the climate benefits of irrigation are just one part of a broader discussion about responsible water use.

Irrigation as an Adaptation Strategy

Beyond increasing yields, irrigation helps farms adapt to changing growing conditions by providing resilience to heat and drought. Maintaining and increasing food production remains a priority, but it is also important to reduce emissions in the food system, which requires understanding how these goals interact.

Conclusion:
Irrigation in U.S. agriculture plays a significant role in reducing greenhouse gas emissions by preventing the conversion of natural lands, while also supporting sustainable food production. Efficient use of water resources and the transition to clean technologies can further enhance the climate effectiveness of the agricultural sector.