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

TL;DR

This study analyzes long-term trends in Australian fire weather conditions using bias-corrected reanalysis data from 1876 to 2011, revealing increasing fire risk linked to climate change-driven humidity and temperature rises.

Contribution

It introduces novel methods and long-term data to better understand and confirm increasing fire weather severity trends in Australia over the past century.

Findings

Significant increase in mean and extreme fire weather indices across Australia.

Humidity and temperature increases are primary drivers of rising fire risk.

Long-term data and new analysis methods strengthen confidence in climate change impacts on fire weather.

Abstract

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.