Dar et al. (2025) Future Climate Projections for Nebraska: Insights from CMIP6 on Precipitation and Temperature Trends

Identification

• Journal: Earth Systems and Environment
• Year: 2025
• Date: 2025-12-27
• Authors: Mehraj U. Din Dar, Ikenna Onyekwelu, Kelechi Igwe, Manavjot Singh, Vaishali Sharda
• DOI: 10.1007/s41748-025-00977-5

Research Groups

• Carl and Melinda Helwig Department of Biological and Agricultural Engineering, Kansas State University, Manhattan, KS, USA
• Department of Agriculture and Natural Resource Management, Schreiner University, Kerrville, TX, USA

Short Summary

This study provides high-resolution (4 km) CMIP6-based climate projections for Nebraska, revealing that by the far future (2060–2098), annual precipitation is projected to increase by up to 25%, while maximum temperatures could rise by 2.5–5.5 °C and minimum temperatures by 2.5–5.5 °C, with a notable 0.2 °C/decade divergence between Tmax and Tmin trends under high emissions.

Objective

• To downscale and bias-correct daily maximum temperature (Tmax), minimum temperature (Tmin), and precipitation predictions from CMIP6 Global Climate Models (GCMs) to a 4 km resolution for Nebraska, and select suitable GCMs based on their ability to mimic observed climate.
• To create a suitable multi-model ensemble for climate projections to assess trends in temperature and precipitation under future climate scenarios.
• To provide gridded datasets for assessing the impacts of climate change on environmental systems in Nebraska.

Study Configuration

• Spatial Scale: 4 km × 4 km (0.04° × 0.04°) grid over Nebraska (12,428 grid points).
• Temporal Scale:
  • Historical period: 1979–2014
  • Near future: 2020–2059
  • Far future: 2060–2098
  • Overall projection period: 2014–2100

Methodology and Data

• Models used:
  • Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Models (GCMs): 24 models initially considered, with 6 selected (EC-Earth 3, EC-Earth 3-CC, EC-Earth3-Veg, EC-Earth3-Veg-LR, GFDL-CM4, GFDL-ESM4).
  • Multi-Model Ensemble (MME) mean.
  • Sen’s slope estimator for trend analysis.
• Data sources:
  • Reference data: gridMET datasets (University of Idaho, 1979–2014, 4 km resolution) for surface meteorological variables.
  • GCM data: Earth System Grid (ESG) data portal for CMIP6 daily outputs of precipitation (Pr), maximum temperature (Tmax), and minimum temperature (Tmin).
  • Future climate scenarios: Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5).
  • Techniques: Kling-Gupta efficiency (KGE) metric for GCM selection, Multi-Criteria Decision Analysis (MCDA), Bilinear interpolation for spatial downscaling, Quantile Mapping (QM) for bias correction.

Main Results

• Precipitation:
  • In the far future (2060–2098), average annual precipitation is projected to increase by 5% to 25% across Nebraska under both SSP scenarios.
  • Spatially, precipitation shows a west-to-east increasing gradient, consistent with historical patterns.
  • Sen's slope analysis indicates overall non-significant trends, but localized increases of 5–15 mm/decade were observed in eastern Nebraska under SSP5-8.5.
• Maximum Temperature (Tmax):
  • In the far future (2060–2098), Tmax is projected to increase by 2.5–3.5 °C under SSP2-4.5 and 5.0–5.5 °C under SSP5-8.5.
  • Sen's slope shows increases of 0.29 °C/decade (near future) and 0.50 °C/decade (far future) under SSP2-4.5, and 0.91 °C/decade (near future) and 0.80 °C/decade (far future) under SSP5-8.5.
• Minimum Temperature (Tmin):
  • In the far future (2060–2098), Tmin is projected to increase by 2.5–3.0 °C under SSP2-4.5 and 4.0–5.5 °C under SSP5-8.5.
  • Sen's slope shows increases of 0.34 °C/decade (near future) and 0.42 °C/decade (far future) under SSP2-4.5, and 0.84 °C/decade (near future) and 0.64 °C/decade (far future) under SSP5-8.5.
• Temperature Divergence: A previously undocumented 0.2 °C/decade divergence between Tmax and Tmin trends was found under the SSP5-8.5 scenario.
• Methodology Performance: Bias correction significantly improved model accuracy; median Root Mean Square Difference (RMSD) for Tmax decreased from 2.5 °C (raw) to 1.2 °C (corrected), and precipitation RMSD dropped from 25% to 12%. The Multi-Model Ensemble (MME) approach consistently yielded more accurate and robust estimates than individual models.

Contributions

• Provides high-resolution (4 km) CMIP6-based climate projections specifically tailored for Nebraska, addressing a critical gap in regional climate data for agricultural, water resources, and ecosystem management impact assessments.
• Reveals a previously undocumented 0.2 °C/decade divergence between maximum (Tmax) and minimum (Tmin) temperature trends under the high-emissions SSP5-8.5 scenario, offering crucial insights for heat stress risks in agricultural systems.
• Demonstrates spatially heterogeneous precipitation responses at 4 km resolution, providing sub-regional contrasts previously unresolved by coarser datasets and enhancing local fidelity for Nebraska.
• Aligns projections with the gridMET/PRISM climatology, ensuring direct compatibility with existing agricultural and hydrological models in the region, thereby reducing bias propagation in impact assessments.

Funding

• NSF EPSCoR RII Track-2 FEC [grant # 2119753, 2022]

Citation

@article{Dar2025Future,
  author = {Dar, Mehraj U. Din and Onyekwelu, Ikenna and Igwe, Kelechi and Singh, Manavjot and Sharda, Vaishali},
  title = {Future Climate Projections for Nebraska: Insights from CMIP6 on Precipitation and Temperature Trends},
  journal = {Earth Systems and Environment},
  year = {2025},
  doi = {10.1007/s41748-025-00977-5},
  url = {https://doi.org/10.1007/s41748-025-00977-5}
}