Fewer cyclones – but they’re getting more intense

When Severe Tropical Cyclone Winston unleashed gale-force winds and powerful storms over Fiji in February 2016, it left 44 people dead and a trail of destruction across much of the region on its way to becoming the most intense cyclone ever recorded in the Southern Hemisphere.

Its impact extended all the way to Australia, with dangerous swells seen on South East Queensland’s beaches and heavy rain dumped in the Far North region of the state.

The disaster came less than a year after Severe Tropical Cyclone Pam pummelled Vanuatu, destroying homes and displacing more than 3,000 people when it struck in March 2015. It too was one of the most severe cyclones ever recorded in the region.

Queensland was then hit by Severe Tropical Cyclone Debbie in 2017 which caused extreme flooding and claimed 14 lives.

A Federation University research team is studying tropical cyclones in the region, and the role climate change is playing in their severity and frequency. The work could lead to improved prediction and projection systems for cyclones in a region where large populations of people live in coastal areas and are vulnerable to their impact.

Dr Savin Chand, who is a Senior Lecturer in Statistics in the School of Science, Engineering and Information Technology, has been working closely with the Bureau of Meteorology, where he was previously a research scientist, and the CSIRO to carry out modelling on the cyclones.

Unlike other weather phenomena, Dr Chand said research in tropical cyclones was not comprehensive because satellite imagery had only become available in recent decades.

“To look at climate change detection and attribution, as we call it, if you detect there is a declining or increasing trend in something, the next part is to determine whether it's due to human causes. So this detection and attribution has been happening, people have been doing a lot of research in the past few decades and some areas are still slightly controversial in the sense that to look at the climate and how things are changing, you need long-term data records,” Dr Chand said.

“For tropical cyclones, we’ve had reliable data since around the 1970s, because that's when satellite operations began and then we started getting consistent records. The last 30 or 40 years of data, looking at trends is not enough to give you the complete picture, this is where the modelling becomes more important.”

Dr Chand said the research had so far shown the number of tropical cyclones globally was going down but their severity was rising.

Changing dynamics in the atmosphere have had a two-fold effect on cyclone activity. A warming atmosphere has made for a more stable environment but as air parcels moved up, the warming meant there was access to more ‘fuel’ in the atmosphere.

“So whatever system moves into the atmosphere, it starts to get a bit stronger because there is more fuel in there for it to burn,” Dr Chand said.

“So the modelling suggests that, overall, even though the cyclone numbers will go down, they will actually get more intense.” Dr Savin Chand

The threat tropical cyclones pose to Pacific Island nations has paved the way for a PhD student from the Solomon Islands to join Dr Chand in Federation University’s Centre for Informatics and Applied Optimization in 2020.

Alick Harihiru will study on an Australia Awards Scholarship, funded by the Department of Foreign Affairs and Trade, and will continue the work examining how tropical cyclone characteristics and their associated risks will change in the Pacific Island countries as a result of global warming.

“When he begins his study, his overall objective will be looking at tropical cyclone impacts in Pacific Island countries with an emphasis in his own country, but we'll fine tune the project so he will look at how tropical cycles have changed over the years and how they have impacted those countries in terms of wind damage and severe rainfall,” Dr Chand said.

The DFAT funding follows a $120,000 grant through the CSIRO and the Australian Bureau of Meteorology’s National Environment Science Program (NESP) to inform decision making and on-ground action on climate change adaptation. The grant was for the extension of a program initially funded with $183,000 in 2017.

“This work will help develop new methods of addressing those uncertainties to make more reliable projections of tropical cyclone activity across different regions in Australia and elsewhere,” Dr Chand said.

The research capability within the Climate Informatics Group, which is led by Dr Chand, will also allow researchers to expand into other areas.

Dr Chand said being a part of a regional university was behind the decision to also focus on a major regional issue – bushfires.

“Another reason we wanted to look at bushfires is because this is a multidisciplinary area. It's not just scientists, not just mathematicians – there are people from all around the university that can get involved,” he said.

“There’s also psychology, bushfire decision-making – there is a lot of interest from a lot of different areas in doing this type of research.”