The widespread heat stress on the Great Barrier Reef, causing huge bleaching events among the corals, has been revealed in new satellite images.
A map, shared by the NASA Earth Observatory, uses temperature data from satellites that show the sea temperature off eastern Australia on March 4. The anomaly also shows the difference in the average sea surface temperature between 2003 and 2014. The map shows just how much the temperatures around Australia's famous Great Barrier Reef has changed.
The reef, which is vital for over a thousand species as well as Australia's economy, is in trouble. The heat stress is causing "widespread coral bleaching."
Bleaching is a process that drains corals of their color, turning them white. Bleaching is brought about by stressors that take a toll on coral health. Drastic changes in water temperatures, light and nutrient availability can all cause bleaching events. While bleaching alone does not cause death, it can increase the likelihood of coral becoming vulnerable and dying.
The most recent bleaching event was confirmed by officials on March 8 and it's the fifth mass bleaching since 2016.
An aerial survey conducted by the Great Barrier Reef Marine Park Authority, of 300 reefs found bleaching in areas stretching over two thirds of the reef, the NASA Earth Observatory reported.
"The results of the aerial survey and the coral bleaching that we are seeing are consistent with the patterns of heat stress that have been building over the reef over the summer months," Roger Beeden, chief scientist at the reef authority, told the NASA Earth Observatory.
Heat stress on corals can trigger a process that causes the corals to expel their zooxanthellae, a type of photosynthetic algae which provides them with nutrients. These nutrients also give the corals their bright colors, which makes them so beautiful to behold.
As the heat expels all these nutrients, the corals loose their color and they are left vulnerable.
Bleaching can occur after four consecutive weeks of higher than usual sea temperatures. If temperatures last longer than that, it can cause "widespread" coral bleaching, according to the NASA Earth Observatory.
This is far from the only bleaching event that has occurred in the Great Barrier Reef. Other mass bleaching events have been recorded in 1998, 2002, 2016, 2017, 2020 and 2022.
Meanwhile, the Pacific Ocean is seeing warmer temperatures recently partly due to El Niño. The weather pattern is causing trade winds to relax, which allows warm water to flow into the Eastern Pacific, where the Great Barrier Reef lies, from the western Pacific.
"Sea surface temperatures during El Niño and La Niña events act a bit like a seesaw," Josh Willis, a climate scientist at Jet Propulsion Laboratory (JPL), told the NASA Earth Observatory. "When ocean temperatures during an El Niño are higher in the eastern Pacific, they're typically lower in the western Pacific."
However, climate change is also contributing to these unusually high temperatures. The Environmental Protection Agency (EPA) reports that over the last three decades sea surface temperatures have kept rising.
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Robyn White is a Newsweek Nature Reporter based in London, UK. Her focus is reporting on wildlife, science and the ... Read more
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