Ukkola et al. (2026) Future changes in seasonal drought in Australia

Identification

• Journal: Hydrology and earth system sciences
• Year: 2026
• Date: 2026-03-23
• Authors: Anna Ukkola, Steven Thomas, Elisabeth Vogel, Ulrike rer. nat. Bende-Michl, Steven T. Siems, Vjekoslav Matic, Wendy Sharples
• DOI: 10.5194/hess-30-1463-2026

Research Groups

• ARC Centre of Excellence for Climate Extremes, UNSW Sydney
• Climate Change Research Centre, UNSW Sydney, Australia
• Bureau of Meteorology, Australia
• Water Research Centre, UNSW Sydney, Australia
• School of Earth, Atmosphere and Environment, Monash University, Australia

Short Summary

This study assesses future seasonal drought changes across Australia using an ensemble of 32 hydrological simulations, revealing widespread increases in meteorological, hydrological, and agricultural droughts, particularly in populated and agricultural regions, with Global Climate Models (GCMs) being the dominant source of uncertainty.

Objective

• To assess future changes in seasonal drought across Australia, considering multiple drought types (meteorological, hydrological, agricultural) and quantifying uncertainties arising from the choice of global climate models (GCMs), downscaling/bias correction (DS-BC) methods, and emissions scenarios.

Study Configuration

• Spatial Scale: Continental Australia, gridded at 0.05° × 0.05° (approximately 5 km × 5 km).
• Temporal Scale: Historical baseline: 1970–2005; Future projections: 2064–2099 (from a full simulation period of 1960–2099, with 1960–1969 as spin-up).

Methodology and Data

• Models used:
  • Hydrological model: Australian Landscape Water Balance model (AWRA-L v6)
  • Global Climate Models (GCMs) from CMIP5: ACCESS1-0, CNRM-CM5, GFDL-ESM2M, MIROC5
  • Regional Climate Model: Conformal Cubic Atmospheric Model (CCAM) for dynamical downscaling
  • Bias Correction Methods: ISIMIP2b (parametric quantile matching), Quantile Matching for Extremes (QME), Multivariate Recursive Nested Bias Correction (MRNBC)
• Data sources:
  • Observed precipitation: Australian Gridded Climate Dataset (AGCD) version 1
  • Observed streamflow: CAMELS-AUS v2 (Catchment Attributes and Meteorology for Large-Sample Studies dataset)
  • Remotely-sensed daily solar radiation data
  • Daily-average wind speed data derived from station-based observations
  • GCM outputs (precipitation, minimum/maximum temperature, wind speed, solar radiation)

Main Results

• Robust future increases are projected for all three drought types (meteorological, hydrological, agricultural) across 20 %–29 % of Australia's land area under the RCP4.5 scenario and 38 %–48 % under RCP8.5.
• The largest increases in drought are projected in winter and spring, particularly in highly populated and agricultural regions of southern and eastern Australia.
• The sign of changes is consistent across different drought metrics (time under drought, duration, intensity), but projections are more robust for the "time spent under drought" metric.
• GCMs are the largest source of uncertainty (47 %–72 % of the full range of projections), followed by downscaling/bias correction (DS-BC) methods (23 %–58 %), with emissions scenarios being the lowest source (11 %–33 %).
• The choice between dynamical (CCAM) and statistical downscaling methods is a significant source of uncertainty in projected future trends.
• GFDL-ESM2M and CCAM-downscaled ensemble members show larger increases in future drought and generally worse performance against historical observations compared to other simulations.

Contributions

• Systematically quantifies and attributes uncertainties in future drought projections to GCMs, downscaling/bias correction methods, and emissions scenarios using a comprehensive ensemble of 32 simulations from the National Hydrological Projections (NHP).
• Provides a robust assessment of future changes across multiple drought types (meteorological, hydrological, agricultural) using consistent methods and evaluating robustness across different drought indicators (time under drought, duration, intensity).
• Offers critical insights into the implications of projected drought changes for Australian agriculture, ecosystems, and urban water supply, particularly in key regions.

Funding

• Australian Research Council (grant nos. CE170100023 and DE200100086)

Citation

@article{Ukkola2026Future,
  author = {Ukkola, Anna and Thomas, Steven and Vogel, Elisabeth and Bende-Michl, Ulrike rer. nat. and Siems, Steven T. and Matic, Vjekoslav and Sharples, Wendy},
  title = {Future changes in seasonal drought in Australia},
  journal = {Hydrology and earth system sciences},
  year = {2026},
  doi = {10.5194/hess-30-1463-2026},
  url = {https://doi.org/10.5194/hess-30-1463-2026}
}