‘I love a sunburnt country,
A land of sweeping plains,
Of ragged mountain ranges,
Of droughts and flooding rains...’
It’s such an Australian weather cliché that it’s enshrined in our national anthem. But the ‘wide brown land' ... 'of droughts and flooding rains’ is set to deliver even more extreme swings going forward, warns Melbourne-based climate scientist Dr Joëlle Gergis.
And she should know: Dr Gergis, currently ARC DECRA Climate Research Fellow in the University of Melbourne’s School of Earth Sciences and recipient, with her project team, of the prestigious Eureka Prize for Excellence in Interdisciplinary Scientific Research in 2014, is constantly thinking about our climate.
From 2009 to 2012, Dr Gergis helmed the South-Eastern Australian Recent Climate History (SEARCH) project, a landmark initiative funded by the Australian Research Council Linkage Projects scheme aimed at reconstructing climate variability in the region from the time of the first European settlement in 1788 to the present.
Since 2009, she's been leading the Aus2K working group for international environmental research organisation Past Global Changes (PAGES). The Aus2K group has been studying Australasian climate variability over the past 2,000 years, coordinating the development of a 1,000-year temperature reconstruction of the region for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).
What Dr Gergis said about recent flooding in northern NSW
In a recent article in The Conversation, Dr Gergis delivered a sobering climatologist’s perspective on the devastating flood damage across northern NSW caused by the tail end of Tropical Cyclone Debbie. She noted that while “flooding is a fact of life in the Northern Rivers” and in the historic floods of 1954 and 1974, the Wilsons River rose to a record 12.17 metres (this time around, it peaked at 11.59m), the recent ‘extreme weather event’ was different.
“Like the current flood, cyclonic rains also caused the 1954 and 1974 events,” Dr Gergen explained. “But unlike those past events, both of which were preceded by prolonged wet weather, almost all of the extreme rainfall from ex-Tropical Cyclone Debbie fell within 24 hours.
“More interesting still is the fact that we are not currently experiencing La Niña conditions, which have historically formed the backdrop to severe flooding in eastern Australia.”Later in the piece, Dr Gergis looked at the recent flooding in northern NSW in the light of her research on historic changes in climate in the region.
“Of course, it is hard to determine the exact impact of climate change on individual storms,” she cautioned. “However, climate scientists are confident about the overall trends.
“Australia’s land and oceans have warmed by 1℃ since 1910, with much of this warming occurring since 1970," said Dr Gergis. "This influences the background conditions under which both extremes of the rainfall cycle will operate as the planet continues to warm. We have high confidence that the warming trend will increase the intensity of extreme rainfall experienced in eastern Australia, including south-east Queensland and northern NSW.
“While it will take more time to determine the exact factors that led to the extreme flooding witnessed in March 2017, we cannot rule out the role of climate change as a possible contributing factor.”
Dr Gergis cited CSIRO's latest climate change projections, which “predict that in a hotter climate we will experience intense dry spells interspersed with periods of increasingly extreme rainfall over much of Australia. Tropical cyclones are projected to be less frequent but more intense on average”.
That, she warned, “potentially means longer and more severe droughts, followed by deluges capable of washing away houses, roads and crops”.
“Tropical Cyclone Debbie’s formation after the exceptionally hot summer of 2016-2017 may well be a perfect case in point, and an ominous sign of things to come,” Dr Gergis said.
A rising star in climatology
The following year, she was one of three national finalists selected for the 2007 Eureka Prize for Young Leaders in Environmental Issues and Climate Change, and one of 19 Wentworth Group of Concerned Scientists’ Science Leaders Scholarship recipients, chosen from a nationwide field.
2007 Australian of the Year Professor Tim Flannery was one of her mentors on the Wentworth program, aimed at “training outstanding young scientists to help bridge the communication gap between science and public policy”.
In 2012, Dr Gergis netted an Australian Research Council (ARC) Discovery Early Career Researcher Award (DECRA) fellowship.
Two years later, she and her team won the prestigious Eureka Prize for Excellence in Interdisciplinary Scientific Research, which “encourages and recognises the pioneering research breakthroughs that can be achieved at the intersection of unrelated, even unexpected, disciplines”.
Most recently, Dr Gergis' work was recognised by the UoM’s Faculty of Science 2015 Dean’s Award for Excellence in Research.