Zhang et al. (2026) Warm and wet spring compensated for the reduction in carbon sinks due to an extreme summer heatwave-drought event in 2022 in southern China

Identification

• Journal: Agricultural and Forest Meteorology
• Year: 2026
• Authors: Yuanyuan Zhang, Fei Jiang, Yanlian Zhou, Guanyu Dong, Dongqiao Wu, Wei He, Jun Wang, Mingda Wu, Hengmao Wang, Lingyu Zhang, Mengwei Jia, Weimin Ju, Jing M. Chen
• DOI: 10.1016/j.agrformet.2026.111060

Research Groups

• Jiangsu Provincial Key Laboratory for Advanced Remote Sensing and Geographic Information Technology, International Institute for Earth System Science, Nanjing University, China.
• Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, China.
• School of Geography and Ocean Science, Nanjing University, China.
• Hubei Climate Center, Wuhan, China.
• Zhejiang University of Technology, Hangzhou, China.
• Department of Geography and Planning, University of Toronto, Canada.
• School of Geographical Sciences, Fujian Normal University, China.

Short Summary

This study quantifies the impact of the record-breaking 2022 summer heatwave-drought on carbon sinks in southern China, finding that a warm and wet spring significantly offset summer carbon losses. While the summer event caused a major decline in photosynthesis, the annual carbon sink in the Yangtze River basin remained relatively stable due to this seasonal compensation.

Objective

• To assess the response of regional terrestrial carbon fluxes to the 2022 compound heatwave-drought (DH2022) in southern China and determine the net annual impact on the regional carbon budget.

Study Configuration

• Spatial Scale: Southern China, with a specific focus on the Middle and Lower reaches of the Yangtze River basin (MLYR) and the Remaining Areas in Southern China (RAS).
• Temporal Scale: The year 2022, specifically comparing the spring and the July–September (JAS) period against a 2015–2021 baseline.

Methodology and Data

• Models used: Global Carbon Assimilation System (GCAS v2) atmospheric inversion model; TRENDYv13 dynamic global vegetation models (for comparison).
• Data sources: OCO-2 satellite $XCO_2$ retrievals; satellite-derived proxies for Gross Primary Productivity (GPP); meteorological reanalysis data.

Main Results

• Summer Impact: During July–September 2022, the MLYR region experienced a reduction in the land carbon sink of 45.8 TgC compared to the 2015–2021 average.
• Spring Compensation: An unusually wet and warm spring in 2022 boosted MLYR vegetation growth, increasing GPP by 46.1 TgC and strengthening the land sink by 24.0 TgC.
• Annual Net Balance: Due to spring compensation, the annual land sink in the MLYR decreased by only 7.1 TgC. In the broader southern China region, the annual land sink actually increased by 42.8 TgC.
• Ecosystem Drivers: The summer sink reduction in the MLYR was driven by GPP declines in forests and grasslands/shrubs, alongside increased ecosystem respiration in croplands.

Contributions

• Provides a high-resolution assessment of the 2022 extreme climate event's impact on the Chinese carbon cycle using satellite-based carbon inversion.
• Highlights the critical role of "seasonal compensation," where favorable conditions in one season (spring) can mitigate the carbon losses from extreme events in another (summer).
• Enhances understanding of how different vegetation types (forests vs. croplands) respond differently to compound heat-drought events.

Funding

• Not explicitly listed in the provided text.

Citation

@article{Zhang2026Warm,
  author = {Zhang, Yuanyuan and Jiang, Fei and Zhou, Yanlian and Dong, Guanyu and Wu, Dongqiao and He, Wei and Wang, Jun and Wu, Mingda and Wang, Hengmao and Zhang, Lingyu and Jia, Mengwei and Ju, Weimin and Chen, Jing M.},
  title = {Warm and wet spring compensated for the reduction in carbon sinks due to an extreme summer heatwave-drought event in 2022 in southern China},
  journal = {Agricultural and Forest Meteorology},
  year = {2026},
  doi = {10.1016/j.agrformet.2026.111060},
  url = {https://doi.org/10.1016/j.agrformet.2026.111060}
}

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