A new study will reveal whether major changes to Western Australia's climate are due to human activities and if they will persist and intensify with increasing greenhouse gas levels.
Research into the causes and extent of climate change in WA will be conducted during the third stage of the Indian Ocean Climate Initiative (IOCI) – a partnership of the State Government, CSIRO, and the Bureau of Meteorology.
A workshop held this week at CSIRO's facilities in Perth marked the beginning of the four-year, $8 million study. Dr Pandora Hope, from the Bureau of Meteorology, says the study will build on past results from IOCI that contributed to the Intergovernmental Panel on Climate Change’s fourth assessment report.
"Our previous work through IOCI showed that observed temperature increase and winter rainfall decline in south-west Western Australia are likely to have been caused by both natural fluctuations and increases in greenhouse gas concentrations," Dr Hope said.
"The results also showed that by 2030 south-west WA would experience a rise in temperatures and a decrease in winter rainfall, with runoff to catchments consequently decreasing by between five and 40pc."
Dr Hope said that in the next stage of IOCI, researchers will investigate how much of the decreased storm development – which led to the sudden decline in WA rainfall in the 1970s – can be explained by natural variations in the climate, or as a consequence of human activity.
While previous work, completed from 1998 to 2006, focussed on winter rainfall in the south-west, the new study will investigate other seasons, recent rainfall declines in the south-west, the intensity of the rainfall events, and present-day and projected climates in the north-west.
Dr Bryson Bates, from CSIRO’s Climate Adaptation National Research Flagship, says the results will support decisions in WA regions that may be particularly affected by climate change and variability issues.
"The new stage of IOCI aims to scientifically underpin the wide range of specific adaptation activities that may be needed by various climate-affected sectors in this region of Australia," he said.
"The results will benefit activities in the north-west of the country, including the culturally, environmentally and economically important Kimberley region.
"While research into the south-west will continue, the new research will look closely at the north-west, where rainfall has been increasing."
A focus of the third stage of IOCI is to improve understanding of the contribution to climate change in the region from factors such as the Asian Brown Cloud, and improve the predictability of tropical cyclones in the Indian Ocean that impact WA.