Shiogama et al. (2025) Emergent constraints on future change projections of mean and extreme temperature and precipitation in the global maize harvesting area

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Identification

• Journal: Environmental Research Letters
• Year: 2025
• Date: 2025-12-29
• Authors: Hideo Shiogama, Masashi Okada, Yuji Masutomi, Toshichika Iizumi
• DOI: 10.1088/1748-9326/ae3194

## Research Groups -

Short Summary

This study investigates whether 'hot' Earth system models (ESMs) overestimate future temperature and precipitation changes in global maize harvesting areas, finding that these models do overestimate changes in mean and extreme temperature and extreme precipitation, with emergent constraints significantly reducing projection uncertainties.

Objective

• To investigate whether 'hot' Earth system models (ESMs) from CMIP6, characterized by past warming trends greater than observations, tend to overestimate future mean and extreme temperature (Δ T ave and Δ T max ) and precipitation (Δ P ave and Δ P max ) changes across global maize harvesting areas during growing seasons.

Study Configuration

• Spatial Scale: Global maize harvesting areas, with specific mention of regions with highest maize production (e.g., USA, China).
• Temporal Scale: Future climate projections (changes during maize growing seasons), constrained by past global mean temperature trends.

Methodology and Data

• Models used: 30 Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6).
• Data sources: Projections from ESMs; past global mean temperature trends (used for emergent constraint, compared against observations).

Main Results

• Mean and extreme future temperature (Δ T ave and Δ T max ) and extreme future precipitation (Δ P max ) changes, averaged over global maize harvesting regions, are significantly correlated with past global mean temperature trends. This indicates that 'hot' ESMs tend to overestimate these future changes.
• Emergent constraints (ECs) reduce the inter-ESM variances in projections for Δ T ave, Δ T max, and Δ P max by 43%, 39%, and 18%, respectively.
• Regions with the highest maize production, such as the USA and China, are projected to experience the greatest increases in Δ T ave and Δ T max.
• The fraction of global maize production exposed to historically rare high temperatures increases substantially in raw projections but is moderated when ECs are applied.

Contributions

• Demonstrates that the use of 'hot' Earth system models may lead to overestimated impacts of climate change on global maize cultivation.
• Provides a robust pathway, through the application of emergent constraint methods, for refining climate change impact assessments on agriculture by reducing projection uncertainties.
• Quantifies the overestimation bias of 'hot' ESMs for key climate variables (mean/extreme temperature, extreme precipitation) relevant to maize production.

## Funding -

Citation

@article{Shiogama2025Emergent,
  author = {Shiogama, Hideo and Okada, Masashi and Masutomi, Yuji and Iizumi, Toshichika},
  title = {Emergent constraints on future change projections of mean and extreme temperature and precipitation in the global maize harvesting area},
  journal = {Environmental Research Letters},
  year = {2025},
  doi = {10.1088/1748-9326/ae3194},
  url = {https://doi.org/10.1088/1748-9326/ae3194}
}