Projected change in meteorological drought characteristics using regional climate model data for the Hunter region of Australia

Abstract

Drought is a natural phenomenon that can have prolonged and widespread impacts on many communities and environments. The impact of climate change on drought is uncertain, which makes it challenging to quantify how future droughts will affect society. This study uses downscaled rainfall data from 4 global climate models (GCMs) and 2 time windows (1990-2009; 2060-2079) to estimate changes in the average length and intensity of single drought events, and the total number of months experiencing drought during each time window for the Hunter region of Australia. This region was chosen as it is economically important for Australia, and will be the focus of future work that examines the social and policy implications of projected climate change impacts on drought and human displacement. The changes in drought characteristics are assessed using Standardised Precipitation Index and deciles approaches, and 2 datasets: (1) downscaled GCM rainfall; and (2) historical gridded rainfall adjusted via a quantile-quantile approach conditioned on the GCM rainfall. Key findings are that the changes in drought characteristics vary spatially across the study region, and are highly dependent on the downscaled GCM rainfall used, with some regions showing opposing changes in drought characteristics between the ensemble members. Further, the change in drought characteristics between the current and future time windows tends to be greater using the downscaled GCM rainfall when compared with the GCM-adjusted historical rainfall. These results pose the question of how GCM projections should be used to develop robust but cost-effective climate adaptation strategies.