U.S. research team says, “If we improve agricultural methods, we can reduce emissions by 10% while maintaining production.”
(Seoul = Yonhap News) Reporter Jooyoung Lee = Over the past 60 years, greenhouse gases emitted from rice fields around the world where rice is grown have doubled, and the increase in methane emissions, which has a greater warming effect than carbon dioxide, was found to have had a particularly significant impact.
On the 23rd, Professor Han Qin Tian's team at Boston College in the U.S. announced in the scientific journal Nature Food that, as a result of analyzing changes in methane, nitrous oxide, and soil carbon related to rice cultivation around the world from 1961 to 2020, they found that greenhouse gas emissions from rice paddy fields currently amount to 1.1 billion tons of carbon dioxide equivalent per year.
The research team said that the expansion of rice cultivation, especially in developing regions, has led to an increase in greenhouse gases emitted from rice fields around the world. In particular, methane production has increased due to the method of returning crop residues such as rice straw left after harvest to flooded rice fields.
Rice is the main food eaten by more than half of the world's population, but as organic matter decomposes in flooded soil of rice paddies, greenhouse gases methane and nitrous oxide are emitted. In particular, as rice cultivation expands and becomes more intensified around the world, greenhouse gas emissions from rice paddies are emerging as an important issue in responding to climate change.
Methane is a greenhouse gas that has a much stronger warming effect than carbon dioxide. The Global Methane Pledge, an international cooperation in which 159 countries around the world participated to respond to the climate crisis, has set a goal of reducing global methane emissions by at least 30%.
In this study, the research team analyzed greenhouse gas emissions and major causes related to rice cultivation, such as methane, nitrous oxide, and soil carbon changes, by combining machine learning techniques learned from more than 21,000 field observation data, process-based ecosystem models, and global meta-analysis data.
Professor Tian, first author of the paper, said: "The goal of the study was to understand the full impact of rice cultivation systems on the climate by considering all major greenhouse gases, not just methane, but to find realistic reduction pathways."
As a result of the analysis, it was found that the total amount of greenhouse gases generated from rice paddies around the world, when converted to carbon dioxide, amounts to approximately 1.1 billion tons per year, which has doubled since the 1960s.
The world's annual rice cultivation area increased from approximately 160.82 million ha in 2015 to 172.48 million ha in 2024. In particular, in Africa, the rice cultivation area in 2024 was 16.2 million ha, a seven-fold increase from 1961.
Professor Tian explained that in East Asia, the method of putting rice straw back into flooded rice fields after harvesting has spread, leading to a resurgence in methane emissions, while Africa has emerged as a new center of greenhouse gas emissions from rice fields due to the rapid increase in rice cultivation area.
However, the research team explained that by optimizing water management, reducing the amount of rice straw put into rice fields after harvest, and increasing the efficiency of nitrogen fertilizer use, greenhouse gas emissions can be reduced by about 10% without reducing harvest. This shows the possibility of substantial reduction.
“This is a practical and scalable solution that farmers can apply immediately,” said Professor Susan Phan, co-author of the paper. “It provides a pathway for the agricultural sector to contribute meaningfully to achieving short-term climate goals, including methane reduction.”
◆ Source: Nature Food, Hanqin Tian et al., ‘Global Rice Paddy Greenhouse Gas Emissions Have Doubled over the Past Six Decades Driven by Area Expansion and Intensified Residue Incorporation’, http://dx.doi.org/10.1038/s43016-026-01355-8
