A new study led by researchers from the University of Adelaide has uncovered evidence that several of K’gari’s iconic freshwater lakes, located on the world’s largest sand island in Australia, dried up around 7,500 years ago despite the region experiencing higher than average rainfall.
The findings, published in the Journal of Quaternary Science, challenge the long-held assumption that abundant rainfall alone is enough to sustain the island’s freshwater lakes. Researchers say changing wind patterns and rainfall distribution may have played a crucial role in the disappearance of the lakes, raising concerns about their future under climate change.
By analysing ancient sediment cores collected from some of K’gari’s oldest lakes, scientists found that sediment layers were missing between approximately 7,500 and 5,500 years ago. The absence of these deposits indicates that parts of the lake basins were dry during that period, preventing the accumulation of sediments.
Lead researcher Associate Professor John Tibby said the discovery was unexpected because the drying occurred during the middle Holocene, a period generally considered wetter than the present. While many Australian lakes have dried during prolonged droughts, K’gari’s lakes disappeared during a comparatively rainy era.
Researchers believe shifts in south east trade winds may have redirected rainfall away from K’gari toward nearby Minjerribah, meaning the island’s lakes received insufficient recharge despite regional rainfall remaining high. The findings suggest that the lakes depend not only on total rainfall but also on where precipitation falls and how atmospheric circulation distributes moisture.
Scientists warned that future climate change, characterised by drier conditions and more intense rainfall events, could pose fresh risks to the long term survival of K’gari’s lakes if rainfall patterns continue to shift.
The study also highlights the cultural significance of the lakes for the Butchulla people, the Traditional Owners of K’gari, who refer to them as the “Eyes of K’gari.” Co-author Conway Burns said the lakes represent sacred places that embody the island’s spiritual and cultural heritage and must be protected for future generations.
Researchers say the findings underscore the need for continued monitoring and improved understanding of how climate change may affect one of Australia’s most significant freshwater ecosystems.