“We have a plan. We know the plan. There is a path to sustainability. If enough people see the path, we may just start down it in time.” — David Attenborough

Climate change is loading up for its next shots on the Great Barrier Reef. But while so many reefs are suffering from mass bleaching events, the Ribbon Reefs, the Swains, and Pompey Reefs are curiously evading severe bleaching. As for how these reefs manage to consistently evade climate change’s shots, the CSIRO’s new research shows these reefs curiously evade bleaching because of cold water from the deep.

This phenomenon is called upwelling: the process of cold, nutrient-rich water rising up from the deep to the sea surface. “We found their survival is due to cold water,” said physical oceanographers Chaojiao Sun, from the CSIRO, and Craig Steinberg, from the Australian Institute of Marine Science. “That is, most of these reefs are periodically bathed in cooler water even as other parts of the reef bake in marine heatwaves. These reefs are called climate refugees – where conditions in a local environment are suitable for life while conditions in neighbouring regions, in this case, reefs, aren’t. “Our modelling suggests cold currents could protect these vital refuges at least into the 2080s, even if high emissions lead to sea surface temperatures 2-3°C hotter than now,” say Sun and Steinburg. They claim this is our best chance to preserve the Great Barrier’s rich array of life, and it might be enough time to allow coral to adapt to new conditions and repopulate other reefs.

The East Australian Current – starting from the top of the Great Barrier Reef and ending near Tasmania – raises cold water to the sea surface, but it only goes past the edge of the continental shelf. The Ribbon Reefs, near the Torres Strait, and Pompey and Swains Reefs, 135 km from Mackay, lie right on the edge of the continental shelf. These reefs get the benefits of the cold current, but other reefs that are close to mainland Australia don’t.

The Great Barrier Reef has endured eight mass bleaching events since 1979. Five have occurred in the past eight years. Climate change is loading its bow and firing more and more often. The big question is how much longer can the Great Barrier endure these bleaching events. Global warming has reduced the number of corals in shallow water reefs by as much as 50%. If temperature increases continue and go beyond 3°C, these reefs would collapse. But if we work together to stop climate change, there might be enough time to allow these corals to reproduce and – possibly – replenish the entire Great Barrier Reef.