Tropical cyclones devastate communities in Australia and around the world every year. Forecasting them accurately is being held back by a lack of data. But thanks to some storm-chasing sea turtles collecting ocean temperatures, that data gap is being filled.
Imagine trying to capture data from the ocean in the middle of a tropical cyclone, with monstrous waves and winds over 200km/h. It would be incredibly dangerous, likely deadly, for humans to attempt.
But that's just what a flotilla of sea turtles armed with oceanographic sensors is doing, and they're gathering information that could be crucial to improve cyclone forecasting and protect communities in the tropics.
Tropical cyclones are among the most destructive and costliest natural disasters, and with climate change driving rising ocean temperatures, keeping tabs on the "fuel" that powers storms is becoming ever more vital.
However, cyclone forecasting, which is key to keeping affected communities safe, suffers from a lack of data - meaning forecasts often fail to accurately capture how a cyclone will behave.
To address this, UNSW Canberra oceanographer Christopher Chapman has been studying data collected by sea turtles with GPS trackers and oceanographic sensors attached to their shells.
What he discovered could revolutionise cyclone forecasting and make communities safer and more resilient during cyclone season.
Tropical cyclones build strength from warm seas, Dr Chapman explained, and a good rule of thumb is that the warmer sea surface temperatures are, the stronger a cyclone will be.
"As a cyclone passes, its winds and waves churn the ocean like a blender, mixing warm surface waters with cooler water below, leaving behind a 'cool wake'," Dr Chapman said.
"This cooling reduces the heat available to the storm, which can in turn limit its strength.
"Cyclone forecasts typically use sea surface temperatures to predict a storm's behaviour and severity, but the deep ocean temperatures are crucially important.
"If cooler water sits just below the surface, it can rapidly cool the ocean and weaken the storm. Conversely, if warm waters extend deeper then the storms have more 'fuel' to draw on."
Despite the importance of deep water temperatures for cyclone forecasts, there is a "data desert" across northern Australia, primarily due to the area being vast, remote and difficult to monitor.
"Traditional tools like ships and ocean gliders can only sample small areas and taking measurements from the middle of a cyclone is dangerous," Dr Chapman said.
"Australia needs an ocean observing system that can work in all weather across this vast region. This is where turtles come in."
Between 2014 and 2024, a team of scientists representing a range of organisations , working with traditional owners, attached miniature GPS trackers and oceanographic probes to the shells of dozens of Olive Ridley and Flatback turtles while they were laying their eggs on beaches from the Pilbara Coast to the Gulf of Carpentaria.
The instruments are attached with a special adhesive that is designed to degrade with the oil produced from the turtle's shell and will remain attached, at most, a year.
The sea turtles captured more than 8000 ocean temperature profiles across much of Northern Australia, from depths as great as 80 metres.
It wasn't until April 2023 when the full extent of these turtle observations and their utility in cyclone forecasting became clear. A tropical storm had formed off the Kimberley coast which would become Cyclone Ilsa, a category five system with 219km/h winds, the highest ever wind speed recorded by the Bureau of Meteorology (BoM).
Deep beneath that maelstrom, swimming along totally unbothered, was one of the instrumented turtles. This turtle captured data from beneath the surface before, during and after the cyclone, and observed the water temperature drop by 2 degrees Celsius due to the storm.
The team then matched turtle data with the BoM's historical storm database and discovered that turtles had captured observations from within five tropical cyclones, noticing significant ocean cooling in all but one of the storms.
"We compared the turtle data with state-of-the-art ocean models and found that the current forecasting system does not account for cool water mixing with warm surface water," Dr Chapman said.
"As such, the ocean-storm feedback is too weak, which can lead to overestimates of cyclone intensity."
Dr Chapman believes expanding the use of cyclone-chasing turtles could drastically improve the accuracy of forecasts, especially in developing nations that lack advanced monitoring capabilities.
"Improving cyclone forecasts depends on reliable deep-sea observations," he said.
"But doing this at scale is expensive and simply not available to many nations that are susceptible to cyclones, including Australia's Indo-Pacific neighbours.
"Turtle monitoring is inexpensive and the data can be transmitted by satellite almost instantaneously, meaning it can inform and update forecasts in real time."
Sea turtles can be the heroes we need to help save lives and livelihoods right across the tropics.
The fieldwork to apply GPS and sensors was a collaboration between the Australian Institute of Marine Science, Macquarie University, Rio Tinto, the Sydney Institute of Marine Science, CSIRO and the University of Western Australia.
A detailed explanation of this research has been recently published in Environmental Research Letters .
