Hassan et al. (2026) The growing threat of spatially synchronized dry-hot events to global ecosystem productivity

Identification

• Journal: Communications Earth & Environment
• Year: 2026
• Date: 2026-01-28
• Authors: Waqar Ul Hassan, Munir Ahmad Nayak, Md Saquib Saharwardi, Harikishan Gandham, Hari Prasad Dasari, Caspar Ammann, David Yates, Ibrahim Hoteit, Yasser Abualnaja
• DOI: 10.1038/s43247-026-03203-w

Research Groups

• Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
• Climate Change Center, King Abdullah University of Science and Technology/National Center for Meteorology, Jeddah, Saudi Arabia
• Department of Civil Engineering, National Institute of Technology, Srinagar, Jammu and Kashmir, India
• National Center for Atmospheric Research, University of Massachusetts Amherst, Boulder, Colorado, USA

Short Summary

This study provides the first global-scale evidence that spatially synchronized dry-hot (DH) events have increased nearly ten-fold over the past four decades, primarily driven by global warming, leading to significantly amplified losses in global ecosystem productivity and crop yields.

Objective

• To identify regions experiencing synchronous dry-hot (DH) events globally.
• To quantify and attribute changes in the occurrence of spatially synchronized DH events to large-scale background warming trends in temperature.
• To illustrate the impact of widespread DH events on global ecosystem productivity and crop yields.

Study Configuration

• Spatial Scale: Global landmass, divided into 44 IPCC AR6 reference regions (excluding Antarctica). Data resolutions: 0.5° × 0.5° for climate data, 30 arc-minutes for crop area, and 0.05° for gross primary production (GPP).
• Temporal Scale: Daily data aggregated to weekly averages/totals for analysis. Study period for climate data: 1 January 1979 to 31 December 2022 (44 years). GPP data covers 2000 to 2019. Analysis distinguishes between pre-2000 (1980–2000) and post-2000 periods.

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI) at a 3-week timescale for identifying dry events.
  • 90th percentile threshold of weekly average daily maximum temperature for identifying hot events.
  • Likelihood Multiplication Factor (LMF) for measuring spatial synchrony.
  • Binomial tests and bootstrapping for statistical significance.
  • Linear regression for detrending temperature data to isolate warming effects.
  • Neural networks for upscaling GPP estimates.
  • Generalized linear regression model for analyzing crop yield anomalies.
• Data sources:
  • National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Centre’s (CPC) Global Unified Gauge-Based Analysis of Daily Precipitation and Temperature dataset.
  • GAEZ+_2015 Monthly Crop Data for crop physical area (Rice, Maize, Wheat).
  • FluxSat v2.0 dataset for daily global gross primary production (GPP), derived from MODIS instruments and FLUXNET 2015 eddy covariance tower sites.
  • Food and Agriculture Organization (FAO) for annual global crop yield data.

Main Results

• The frequency of widespread spatial synchrony (defined as five or more IPCC regions simultaneously experiencing DH events) has increased nearly ten-fold over the past four decades, from 2 weeks in the 1980s to 24 weeks in the recent decade, while confined events (1-2 regions) have declined.
• This rapid synchronization, particularly since 2000, is largely attributed to global warming, accounting for approximately 80–85% of the observed increase in synchrony.
• The risk of widespread DH events increased by approximately 23% in the actual warming scenario compared to about 6% in a detrended (non-warming) scenario.
• Spatially synchronized DH events lead to substantially larger (double) global ecosystem productivity losses compared to spatially confined events. The average global GPP loss during a widespread DH event is approximately 0.75% of global GPP, equivalent to about 2.0 megatonnes of carbon per day.
• Cropland productivity losses are approximately 1.5 times higher than in global land areas during DH events.
• Wheat croplands exhibit the strongest productivity losses during synchronized DH events (approximately 0.17% of GPP per 1% increase in affected area), followed by maize (approximately 0.07–0.09%), with weaker effects for rice.
• Negative relationships were observed between detrended global annual crop yield and the detrended annual frequency/extent of widespread synchronous DH events during critical growing stages, with wheat showing the strongest sensitivity.
• Larger percentage GPP losses were experienced in the southern subtropics compared to the northern subtropics, potentially due to more limited irrigation infrastructure.

Contributions

• Provides the first global-scale quantification of the increasing spatial synchrony of compound dry-hot (DH) events and their amplified impacts on ecosystem productivity and crop yields.
• Demonstrates that the observed rapid increase in widespread synchronized DH events since 2000 is primarily driven by accelerated global warming, highlighting a critical tipping point in the climate system.
• Employs a fine-scale, sub-seasonal approach, offering a more comprehensive understanding of DH event synchronization compared to previous regional or seasonal analyses.
• Offers a more realistic assessment of systemic risks to global food security by considering simultaneous impacts across multiple key breadbasket regions.
• Documents observed trends in spatial synchrony, which is crucial for evaluating climate models and improving future projections of extreme events.
• Identifies the non-linear effects of warming on the extent and synchronization of DH events.

Funding

• Climate Change Center, an initiative of the National Center for Meteorology (NCM), Kingdom of Saudi Arabia (Ref No: RGC/03/4829-01-01).

Citation

@article{Hassan2026growing,
  author = {Hassan, Waqar Ul and Nayak, Munir Ahmad and Saharwardi, Md Saquib and Gandham, Harikishan and Dasari, Hari Prasad and Ammann, Caspar and Yates, David and Hoteit, Ibrahim and Abualnaja, Yasser},
  title = {The growing threat of spatially synchronized dry-hot events to global ecosystem productivity},
  journal = {Communications Earth & Environment},
  year = {2026},
  doi = {10.1038/s43247-026-03203-w},
  url = {https://doi.org/10.1038/s43247-026-03203-w}
}