Abstract
Algal blooms are becoming more frequent and intense in lakes worldwide, but how bloom intensity and timing co-vary at the global scale is unclear. Here we analyze two decades of Moderate Resolution Imaging Spectroradiometer satellite observations for 4085 lakes ( > 20 square kilometres) to compare changes in intensity (fractional floating algal cover) and timing (start and end dates) of surface algal bloom. We find that intensity and timing often change independently: about 71% of lakes show increasing intensity, mainly associated with higher population density and agricultural pressure, whereas temperature and wind better explain shifts in bloom timing, especially in cold regions. Under a medium-emission scenario, tropical lakes show rapid intensification with modest timing shifts, while cold-region lakes exhibit regionally contrasting timing changes. This decoupling may alter lake food webs and carbon cycling, underscoring the need for region-specific management strategies under climate change.
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Data availability
The MODIS images, Landsat images, and the GSWO dataset are available in the Google Earth Engine dataset (https://developers.google.com/earth-engine/datasets/catalog). The HydroLAKES dataset was downloaded from https://www.hydrosheds.org/products/hydrolakes, and the HydroBASINS dataset was obtained from https://www.hydrosheds.org/products/hydrobasins. The climate data were obtained from https://data.isimip.org/search/tree/ISIMIP3b/SecondaryInputData/climate/atmosphere/mri-esm2-0/. The population density data were obtained from https://data.isimip.org/search/tree/ISIMIP2b/SecondaryInputData/socioeconomic/pop. The CROP data were obtained from https://luh.umd.edu/data.shtml. The GDP dataset was obtained from https://zenodo.org/records/7898409. The land surface temperature data used to select lakes were obtained from https://disc.gsfc.nasa.gov/datasets/FLDAS_NOAH01_C_GL_M_001/summary. Nitrogen and phosphorus fertilizer usage data was downloaded from https://doi.org/10.1594/PANGAEA.863323. The processed lake-level datasets generated in this study, including mean bloom phenology, long-term trend metrics, future projection outputs, and the source data underlying the main figures and selected Supplementary Figs., are available in Figshare at https://doi.org/10.6084/m9.figshare.3144986587.
Code availability
Example scripts illustrating the core analytical workflow used in this study are available in Figshare at https://doi.org/10.6084/m9.figshare.3148922288. The code package includes: (1) an example script for FAC calculation for one lake, (2) an example daily FAC CSV output, (3) a MATLAB function for bloom phenology estimation from daily FAC time series, and (4) a MATLAB function for PCA and PCR.
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Acknowledgements
The authors thank the colleagues from NIGLAS (Hanhan Li, Xiqoqi Wei, Zehui Huang, Haoze Liu, Xinhui Chen, Yiqiu Wu, Zhengyang Yu, Mingming Deng) for their help with field measurements and data collections. This work was supported by the National Natural Science Foundation of China (Nos. 42361144002, 42371371, and 42301406), and the National Key R&D Program of China (No. 2022YFF0711603).
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Kun Xue: Methodology, data curation, formal analysis, visualization, and writing of the original draft. Ronghua Ma: Conceptualization, supervision, funding acquisition, editing of the manuscript. Minqi Hu: Data processing, formal analysis, review, and editing of the manuscript. Yao Li: Data analysis, review, and editing of the manuscript.
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Communications Earth and Environment thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editors: Somaparna Ghosh A peer review file is available.
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Xue, K., Ma, R., Hu, M. et al. Anthropogenic and climatic factors regulate algal bloom intensity and timing in global lakes under climate change. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03446-7
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DOI: https://doi.org/10.1038/s43247-026-03446-7
