Andrew Dowdy | Searcharxiv

arXiv2026

Increasing trends in the severity of Australian fire weather conditions over the past century

Understanding how weather and climate influence fire risk is important for many purposes, including climate adaptation planning and decision-making in sectors such as emergency management, finance, health and infrastructure (e.g., for energy and water availability). In this study, bias-corrected 20CRv2c reanalysis data are used to investigate the climatology and long-term trends of weather conditions associated with landscape fires in Australia. The McArthur Forest Fire Danger Index (FFDI) is used here as a broad-scale representation of weather conditions known to influence fire behaviour based on wind speed, humidity, temperature and rainfall measures. In particular, using this reanalysis dataset allows analysis over a longer time period than previous studies, from 1876 to 2011. Another novel aspect is that trends are examined using several different approaches, including a method to help account for the influence of interannual drivers of climate variability not previously used for fire weather analysis. Results show increases in mean and extreme seasonal FFDI values throughout Australia in general, with all statistically significant trends being positive in sign for individual climate zones. Humidity and temperature trends, attributable to human-caused climate change, are shown to be the main cause of the increase in dangerous weather conditions for fires. These findings build on previous studies, with the novel data and methods used adding confidence to the overall understanding of fire risk factors in a changing climate.

physics.ao-ph↗

arXiv2025

Climatological variability of a thunderstorm environment dataset in tropical and temperate regions

Spatiotemporal variations in thunderstorm occurrence frequency are considered here using an environmental dataset derived from ERA5 reanalysis data. Interannual variability in the thunderstorm environments is examined for the period 1979-2023, with the standard deviation and coefficient of variation showing considerable spatial differences through the world. Atmospheric and oceanic modes of climate variability account for some of this interannual variability, particularly for the El Nino-Southern Oscillation through tropical and maritime regions, as well as to a lesser degree for the Indian Ocean Dipole, Arctic Oscillation and Antarctic Oscillation. Long-term trends can also contribute to interannual variability, with results showing increases are more common than decreases in the thunderstorm environments through the study region over the period 1979-2023. However, considerable uncertainties in those trends are noted as is also suggested from some additional analysis of global climate models, indicating that although more favorable thunderstorm environments might occur in a warming world, the estimated change over the period 1979-2023 is relatively small compared to the standard deviation in most locations. The study findings are intended to be complementary to other studies and contribute as part of a broader range of information available on thunderstorms and climate variability.

physics.ao-ph↗