Guo et al. (2026) Shortened Wet Seasons in the Southern Hemisphere Land under Global Warming

Identification

• Journal: Journal of Climate
• Year: 2026
• Date: 2026-10-15
• Authors: Jinyuan Guo, Fengfei Song, Lu Dong, Tianjun Zhou, Jian Lu, Lai-Yung Ruby Leung, Lixin Wu
• DOI: 10.1175/jcli-d-25-0439.1

Research Groups

• Frontier Science Center for Deep Ocean Multispheres and Earth System and Physical Oceanography Laboratory, Ocean University of China, Qingdao, China
• Laoshan Laboratory, Qingdao, China
• College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
• Laboratory for Ocean Dynamics and Climate, Qingdao Marine Science and Technology Center, Qingdao, China
• LASG, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing, China
• University of Chinese Academy of Sciences, Beijing, China
• Atmospheric, Climate, and Earth Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA

Short Summary

This study investigates changes in wet season length under global warming, revealing a robust shortening in Southern Hemisphere land regions, primarily driven by a greater delay in wet season onset than cessation due to asymmetric changes in latent heat flux.

Objective

• To understand how the length of wet seasons in tropical and subtropical land regions changes under global warming, specifically differentiating between the Northern and Southern Hemispheres, and to identify the underlying physical mechanisms.

Study Configuration

• Spatial Scale: Global, focusing on tropical and subtropical land regions, with distinct analyses for the Northern and Southern Hemispheres.
• Temporal Scale: Comparison between current climate and future global warming scenarios, analyzing changes in the annual cycle of precipitation.

Methodology and Data

• Models used: 27 CMIP6 models.
• Data sources: Model projections from CMIP6, analyzed using an atmospheric energetic framework.

Main Results

• In the Northern Hemisphere, wet season onset and cessation shift later at a similar pace, resulting in modest changes in wet season length.
• In contrast, significant changes in wet season length are concentrated in the Southern Hemisphere, where 23 of the 27 CMIP6 models project a shortening of the wet season.
• The multi-model mean reduction in wet season length for the Southern Hemisphere is 3.70 days.
• This shortening is accompanied by a larger delay in wet season onset compared to cessation.
• The shortened wet season over the Southern Hemisphere is closely aligned with asymmetric changes in the divergence of atmospheric energy transport between the onset and cessation stages.
• These asymmetric changes are mainly determined by the net energy input to the atmosphere, dominated by the latent heat flux.
• Future asymmetric changes in latent heat flux are strongly influenced by precipitation-latent heat flux coupling, which is stronger during the onset stage than during the cessation stage in the current climate.

Contributions

• Provides a novel and comprehensive analysis of changes in wet season length under global warming, an aspect previously less understood compared to changes in amplitude and phase.
• Identifies a robust and significant shortening of wet seasons specifically over Southern Hemisphere land regions.
• Elucidates the physical mechanisms driving this shortening, linking it to asymmetric changes in atmospheric energy transport, latent heat flux, and the coupling between precipitation and latent heat flux.

Funding

• Not specified in the provided text.

Citation

@article{Guo2026Shortened,
  author = {Guo, Jinyuan and Song, Fengfei and Dong, Lu and Zhou, Tianjun and Lu, Jian and Leung, Lai-Yung Ruby and Wu, Lixin},
  title = {Shortened Wet Seasons in the Southern Hemisphere Land under Global Warming},
  journal = {Journal of Climate},
  year = {2026},
  doi = {10.1175/jcli-d-25-0439.1},
  url = {https://doi.org/10.1175/jcli-d-25-0439.1}
}