Swain et al. (2025) Africa’s booming rice cultivation is fueling regional warming

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-12-01
• Authors: Basudev Swain, Marco Vountas, Aishwarya Singh, Rui Song, Nidhi L. Anchan, Nisha Patel, D. Tripathy, K. P. Swain, Dukhishyam Mallick, Richard Alawode, Sachin S. Gunthe
• DOI: 10.1038/s41598-025-27436-5

Research Groups

• Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, UK
• Institute of Environmental Physics, University of Bremen, Bremen, Germany
• Centre for Atmospheric and Climate Sciences, Indian Institute of Technology Madras, Chennai, India
• School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
• Biogeochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
• National Centre for Earth Observation, Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, UK
• Department of Energy, Environmental, and Chemical Engineering, Washington University, Saint Louis, MO, USA
• Department of Environmental Meteorology, University of Kassel, Kassel, Germany
• Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
• Chester F. Carlson Center for Imaging Science, Rochester Institute Institute of Technology, Henrietta, USA
• IJCLab Orsay, CNRS/IN2P3, Université Paris-Saclay, Saclay, France
• Leipzig Institute for Meteorology, Leipzig University, Leipzig, Germany

Short Summary

This study investigates the link between the rapid expansion of rice cultivation in Africa and regional warming, finding that a 436% increase in cultivation area (1960-2018) is associated with a 603 million tonne rise in agricultural methane emissions, contributing to a 1.3 °C increase in surface air temperature anomaly.

Objective

• To investigate the association between the rapid expansion of rice cultivation and associated methane emissions in Africa during the industrial period (1960-2018) and its impact on the rising regional surface air temperature, relative to the pre-industrial baseline (1850-1900).

Study Configuration

• Spatial Scale: African continent, specifically Sub-Saharan Africa, with a focus on West African nations (e.g., Nigeria).
• Temporal Scale: Pre-industrial period (1850–1900), Industrial period (1960–2018), Historical period (1850–2005), and post-2005 period extended to 2018 using RCP4.5 scenario.

Methodology and Data

• Models used:
  • CMIP5 climate models (15 selected models: NorESM1-M, MPI-ESM-LR, IPSL-CM5A-LR, CCSM4, IPSL-CM5A-MR, GFDL-CM3, MIROC5, CSIRO-Mk3-6-0, HadGEM2-CC, CNRM-CM5, GISS-E2-H, FGOALS-g2, HadGEM2-ES, MIROC-ESM, GISS-E2-R, CanESM2, Bcc-csm1-1, BNU-ESM).
  • Regular Optimal Fingerprinting (ROF) method.
  • Iteratively Reweighted Least Squares (IRLS) method for trend estimation.
• Data sources:
  • HadCRUT5 observational Surface Air Temperature (SAT) data.
  • CMIP5 model simulations (historical and RCP4.5 scenarios for Greenhouse Gas (GHG), Anthropogenic Aerosol (Aaer), Natural (NAT), and Land-Use (LU) forcings).
  • Food and Agriculture Organization database (FAOSTAT) for area harvested for rice cultivation.
  • Our World in Data for methane emission data from agricultural activities.

Main Results

• The area dedicated to rice cultivation in sub-Saharan Africa surged by 436% (14 million hectares) during the industrial period (1960-2018).
• This expansion is associated with an increase of 603 million tonnes in agricultural methane emissions (rising from 347 million tonnes in 1990 to 603 million tonnes in 2018), making agriculture the largest source of methane in Africa.
• These changes are linked to an increase in the total surface air temperature anomaly to 1.3 °C (from an average of 0.3 °C in 1960 to 1.3 °C in 2018 relative to the pre-industrial baseline).
• Greenhouse gas (GHG) forcing alone is attributed to a rise in surface air temperature from 0.47 °C to 0.92 °C (5–95% range) over Africa during the industrial era compared to the pre-industrial baseline, as estimated by the Regular Optimal Fingerprinting (ROF) method.
• Anthropogenic aerosols contributed a cooling effect ranging from -1.82 °C to -1.36 °C, while natural forcings had a negligible impact (-0.03 °C to 0.06 °C).
• A strong Pearson correlation coefficient (R > 0.90) was found between rice cultivation area, agricultural methane emissions, and surface air temperature anomalies during the industrial period.
• Spatially resolved analysis showed GHG-driven warming trends intensifying from approximately 0.04 °C per decade during the pre-industrial period to 0.26 °C per decade in the industrial era.

Contributions

• This study is the first to establish a direct link and quantify the association between the rapid expansion of rice cultivation and its associated methane emissions with rising regional surface air temperature in Africa.
• It identifies rice cultivation as a significant, previously under-emphasized, contributor to Africa's regional warming, complementing existing attributions to urbanization and industrial emissions.
• Provides foundational evidence and highlights the urgent need for climate-smart agricultural strategies to mitigate methane emissions while ensuring food security in Africa.

Funding

Open Access funding enabled and organized by Projekt DEAL.

Citation

@article{Swain2025Africas,
  author = {Swain, Basudev and Vountas, Marco and Singh, Aishwarya and Song, Rui and Anchan, Nidhi L. and Patel, Nisha and Tripathy, D. and Swain, K. P. and Mallick, Dukhishyam and Alawode, Richard and Gunthe, Sachin S.},
  title = {Africa’s booming rice cultivation is fueling regional warming},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-27436-5},
  url = {https://doi.org/10.1038/s41598-025-27436-5}
}