Why deadly weather events will increase in future
A NEW comprehensive study of Australian natural hazards paints a picture of increasing heat waves and extreme bush fires as this century progresses, but with much more uncertainty about the future of storms and rainfall.
Published in a special issue of the international journal Climatic Change, the study documents the historical record and projected change of seven natural hazards in Australia: flood; storms (including wind and hail); coastal extremes; drought; heatwave; bushfire; and frost.
"Temperature-related hazards, particularly heat waves and bush fires, are increasing, and projections show a high level of agreement that we will continue to see these hazards become more extreme into the 21st century," said the special issue editor Associate Professor Seth Westra, head of the Intelligent Water Decisions group at the University of Adelaide.
"Other hazards, particularly those related to storms and rainfall, are more ambiguous.
"Cyclones are projected to occur less frequently but when they do occur they may well be more intense.
"In terms of rainfall-induced floods we have conflicting lines of evidence with some analyses pointing to an increase into the future and others pointing to a decrease.
"One thing that became very clear is how much all these hazards are interconnected.
"For example drought leads to drying out of the land surface, which in turn can lead to increased risk of heat waves and bush fires, while also potentially leading to a decreased risk of flooding."
The importance of links between climate extremes was also noted in the coastal extremes paper.
"On the open coast, rising sea levels are increasing the flooding and erosion of storm-induced high waves and storm surges," said CSIRO's Dr Kathleen McInnes, the lead author of the coastal extremes paper.
"However, in estuaries where considerable infrastructure resides, rainfall run-off adds to the complexity of extremes."
This special issue represents a major collaboration of 47 scientists and 11 universities through the Australian Water and Energy Exchange Research Initiative (www.ozewex.org), an Australian research community program.
The analyses aim to disentangle the effects of climate variability and change on hazards from other factors such as deforestation, increased urbanisation, people living in more vulnerable areas, and higher values of infrastructure.
"The study documents our current understanding of the relationship between historical and possible future climatic change with the frequency and severity of Australian natural hazards," Associate Professor Westra said.
"These hazards cause multiple impacts on humans and the environment and collectively account for 93% of Australian insured losses, and that does not even include drought losses.
"We need robust decision-making that considers the whole range of future scenarios and how our environment may evolve," he said.
"The biggest risk from climate change is if we continue to plan as though there will be no change. One thing is certain: our environment will continue to change."