Rice paddy greenhouse gas emissions have doubled during the past 60 years—but practical farm changes could cut methane emission and support global climate targets without reducing food production, a team led by Boston College scientists reports today in the journal Nature Food.
Rice feeds more than half the world's population, but has a growing climate footprint. Flooded paddies emit methane and nitrous oxide, two powerful greenhouse gases. As rice farming intensifies worldwide, understanding its methane footprint—and how to reduce it without threatening food security—has become a global priority.
"Our goal was to understand the full climate impact of rice systems—not just methane, but all major greenhouse gases together—and to identify realistic pathways for mitigation," said Boston College Professor of Earth and Environmental Sciences Hanqin Tian, lead author of the report and director of the Center for Earth System Science and Global Sustainability at the Schiller Institute for Integrated Science and Society.
Since the 1960s, greenhouse gas emissions from rice paddies have doubled to approximately the equivalent of 1.1 billion tons of carbon dioxide annually, the researchers report. Methane is a major contributor, particularly in regions such as East Asia, while Africa is emerging as a new hotspot due to expanding rice cultivation, according to the study.
Methane is especially important because it drives near-term warming, making it a central focus of global climate efforts such as the Global Methane Pledge, which aims to cut methane emissions by at least 30 percent this decade, said Tian, who also directs the Global Carbon Project's Boston Office.
This study provides the most comprehensive global assessment of rice-related greenhouse gas emissions to date, covering methane, nitrous oxide, and soil carbon changes from 1961 to 2020, Tian said. Annual global rice cultivation ranged from 397.4 million acres in 2015 to 426 million acres in 2024.
The researchers combined machine learning trained on more than 21,000 field observations, a process-based ecosystem model, and a global meta-analysis. By integrating these approaches, Tian said the team quantified total emissions, identified key drivers such as land expansion and residue management, and evaluated how future mitigation strategies could contribute to climate targets—including methane reduction goals under international initiatives.
Tian said the team wanted to quantify the role rice paddy cultivation plays in global greenhouse gas emissions—especially methane—and the factors driving their rapid increase. Just as crucial was understanding how emissions can be reduced through realistic changes in farming practices, and the potential for reductions to contribute to climate goals set by entities such as the Global Methane Pledge, which counts 159 participating countries.
Tian and colleagues from Alcorn State University, Auburn University, Stanford University, University of Maryland, and France's University of Versailles Saint-Quentin-en-Yvelines identified two dominant drivers behind the six-decade surge in emissions:
Expansion of rice cultivation, particularly in developing regions, which has increased total emissions globally
Intensified residue incorporation, where crop residues are returned to flooded soils, boosting methane production
Regionally, East Asia experienced renewed methane increases linked to heavy straw incorporation, while Africa emerged as a fast-growing emissions hotspot as rice cultivation acreage increased seven-fold between 1961 and 2024, to 40 million acres, Tian said.
Despite rising emissions, the study highlights a clear opportunity: improved farm management could reduce emissions by about 10 percent without compromising yields. Key strategies include: optimizing water management to reduce methane formation, reducing excessive residue return to soils, and improving nitrogen fertilizer efficiency.
"These are practical, scalable solutions that farmers can adopt today," said study co-author and Boston College Associate Professor of Engineering Susan Pan, research director at the Center for Earth System Science and Global Sustainability. "They offer a meaningful pathway for agriculture to contribute to near-term climate targets, including methane reduction goals."
