Understanding intensification of short-duration rainfall extremes

The Royal Society - the world’s oldest scientific academy dating back to 1660 –  recently convened a meeting bringing together some of the most eminent scientists from across the globe to discuss rainfall extremes. The group’s purpose was to integrate and synthesise research results from different international groups working in this area and set the agenda for future research addressing gaps in understanding about the impact of climate change on rainfall patterns.

Representatives included leading research institutions such as the Lawrence Berkeley National Laboratory USA, the National Center for Atmospheric Research USA, Massachusetts Institute of Technology (MIT), the UK Met Office Hadley Center, ETH Zurich, Newcastle University (UK) and meteorological institutes from the Netherlands and Sweden.

Dr Conrad Wasko standing on gravel driveway with Royal Society building in background
Dr Conrad Wasko at the Royal Society

McKenzie Fellow Dr Conrad Wasko was invited to present his research on understanding the dependence of short-duration rainfall extremes to rising temperatures. His research has been awarded the Lorenz G Straub Award and MSSANZ Early Career Research Excellence Award. As modelling changes to future short-duration rainfall extremes is extremely difficult, Dr Wasko focuses on investigating the historical relationship of rainfall with temperature to gain insights on how extremes may change in the future.

As the Earth and its atmosphere warm, saturation vapor pressure increases as a percentage per degree Celsius. Dr Wasko's research indicates a rate of increase of 6-7%/°C present across Australia, with dependencies greater than this observed for sub-daily rainfall extremes suggesting dynamic intensification of extreme storm events with higher temperatures.

Further, by investigating the pattern of storms, his research has shown that is the most intense portion of a storm is the most likely to intensify with higher temperatures with implications for greater flash flooding with the higher temperatures climate change is expected to bring.

Country field with storm in background and lightning on left of image
Storm over Bolgart in Western Australia

The meeting concluded with consensus that extreme rainfalls will intensify with climate change, with rainfall  patterns likely to change causing further intensification and worsening of flash flooding in urban areas. It was decided that future research should focus on understanding the mechanics behind these changes so that the magnitude of the changes are able to be robustly projected allowing practicing engineers to adopt these changes in rainfall and have confidence in their infrastructure design.

In the wake of extreme weather events across Australia’s east coast in particular, as we battled bushfires and flooding simultaneously, Dr Wasko’s work will inform crucial decision making to allow for more effective climate change adaptation.

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