Changes and uncertainty in future drought risk over Australia.

Abstract:

Droughts pose significant threats to society, causing economical losses, condemning populations to famine, and often triggering a cascade of hazards related to wildfires and post-fire hazards. The 2019 bush fires in Australia is a great example of the impacts of the prolonged drought conditions that preceded the fires that devastated the landscape, resulted in significant losses of life and property and drove many species to the verge of extinction. Understanding and predicting drought characteristics, such as severity and duration, and their frequency of occurrence is necessary for developing effective mitigation strategies. The anticipated intensification of droughts due to global warming, further emphasizes the need for developing robust climate adaptation strategies in order to better cope with drought impacts in the future. Future climate projections are associated with significant uncertainty, an important element to consider when estimating future drought risk.

In this work, we carry out an analysis on the changing characteristics of droughts and their corresponding uncertainty in future climate. Analysis is carried out over Australia based on ERA5-Land (1981-2019) and an ensemble of global climate models (2020-2099) and emission scenarios (RCP2.6 and 8.5). Drought events and their characteristics are estimated based on two widely used drought indices, SPI and SPEI. Comparison between the two indices is carried out to investigate potential index-dependence of the results. Lastly, a novel statistical framework is used to estimate severity-duration-frequency curves for different periods. Results demonstrate a consistent increase on future drought risk but a considerable variability in drought severity and space-time dynamics for different climate projections.