Narinesingh et al. (2025) Modeling Northern Hemisphere Heat Extremes in Current and Warmer Climates: Intensity, Duration, and Physical Drivers

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Climate
• Year: 2025
• Date: 2025-12-15
• Authors: Veeshan Narinesingh, Joseph P. Clark, David Paynter, Zhihong Tan, Berenize Garcia Nueva, Kristopher Rand
• DOI: 10.1175/jcli-d-25-0013.1

Research Groups

Not explicitly mentioned in the abstract.

Short Summary

This study examines the intensity, duration, and physical drivers of Northern Hemisphere summer heat extremes using observations, reanalyses, and CMIP6 models, finding that models generally capture observed variations but exhibit biases in duration where diabatic effects dominate, and project increased intensity in several regions under future warming scenarios.

Objective

• To examine the intensity, duration, and physical drivers of Northern Hemisphere summer heat extremes in observations, reanalyses, CMIP6 models, and prescribed sea surface temperature (SST) simulations representing historical- and future-projected climates, specifically investigating how the tail of temperature anomaly distributions changes in projections.

Study Configuration

• Spatial Scale: Northern Hemisphere, with regional focus on eastern India, southern North America, Mexico, Central America, northeastern South America, Southeast United States, Sahel, central Africa, polar regions, Greenland, northwest Canada, and northern Africa.
• Temporal Scale: Summer heat extremes, covering historical periods and future projections for the late twenty-first century under Shared Socioeconomic Pathway (SSP) 2–4.5 and SSP5–8.5 scenarios. Anomalies are defined relative to a 29-day × 11-year running mean.

Methodology and Data

• Models used: CMIP6 models, prescribed sea surface temperature (SST) simulations, coupled ocean simulations.
• Data sources: Observations, reanalyses.

Main Results

• Models generally capture the observed regional variations of intensity and duration of Northern Hemisphere summer heat extremes.
• The magnitude of 90th percentile temperature anomalies shows a positive meridional gradient with zonal variation, but models exhibit warm biases over eastern India and southern North America.
• Both reanalysis and climate model simulations show positive biases in the duration of heat extremes in regions where diabatic effects dominate, specifically Mexico extending through Central America, northeastern South America, and India.
• Heat extreme biases do not appear to be driven by sea surface temperature (SST), based on comparisons between prescribed SST and coupled ocean simulations.
• Future projections for the late twenty-first century under medium (SSP2–4.5) and high (SSP5–8.5) emission scenarios demonstrate agreement for more intense anomalies over the Southeast United States, the Sahel and central Africa, and polar regions.
• Projections also indicate weaker anomalies over Greenland, attributed to melting ice.
• Model agreement on changes in duration is lesser, likely due to internal variability, but nonetheless projects increased duration over the Northwest and Southeast United States and a reduction in northwest Canada and northern Africa.

Contributions

• Comprehensive examination of intensity, duration, and physical drivers of Northern Hemisphere summer heat extremes across a range of observational, reanalysis, and climate model datasets.
• Identification and characterization of regional biases in heat extreme duration in models, linking them to the dominance of diabatic effects and ruling out SST as the primary driver.
• Provision of future projections for changes in heat extreme intensity and duration under different emission scenarios (SSP2–4.5 and SSP5–8.5), highlighting regions of model agreement and disagreement.
• Application of a 90th percentile anomaly definition relative to a running mean to analyze changes in the tail of temperature anomaly distributions.

Funding

Not mentioned in the abstract.

Citation

@article{Narinesingh2025Modeling,
  author = {Narinesingh, Veeshan and Clark, Joseph P. and Paynter, David and Tan, Zhihong and Nueva, Berenize Garcia and Rand, Kristopher},
  title = {Modeling Northern Hemisphere Heat Extremes in Current and Warmer Climates: Intensity, Duration, and Physical Drivers},
  journal = {Journal of Climate},
  year = {2025},
  doi = {10.1175/jcli-d-25-0013.1},
  url = {https://doi.org/10.1175/jcli-d-25-0013.1}
}