Climate Change Is Turning Australia’s Sea Turtles Female

A new scientific paper from the US-based National Oceanic and Atmospheric Administration warns that increasingly warm conditions around Australia's northern Great Barrier Reef are drastically affecting its populations of green sea turtles—a species with temperature dependent sex-determination. According to the paper, being incubated in warmer nests means the vast majority of sea turtles are hatching as females, spelling disaster for reproduction of the species further down the line.

As per this new research, and as has been hinted at by marine scientists in multiple similar studies over the past few years, tiny temperature changes can have a drastic effect on turtle hatchling populations. In the northern Great Barrier Reef, 99 percent of turtles are hatching female. In the slightly cooler southern part of the reef, between 65 percent and 69 percent of turtles are hatching female.

Using more than 20 years of temperature data, the paper's researchers are confident that turtle populations have been breeding more female turtles than male for a while now.

“Combining our results with temperature data show that the northern Great Barrier Reef green turtle rookeries have been producing primarily females for more than two decades and that the complete feminisation of this population is possible in the near future,” they write.

It’s not just the female turtle revolution we have to worry about. The paper also asserts that higher temperatures make the entire reproductive process more fraught, as it is harder for turtle hatchlings to survive past infancy in hotter conditions.

It will take a while for these temperature increases to seriously affect green sea turtle reproduction—if they reach maturity in the first place, sea turtles can live for 70 years, and they only start breeding at the quarter century mark. Still, if global warming doesn’t slow down, the future looks bleak for the Great Barrier Reef and some its most beloved inhabitants. Green sea turtle populations around the world will be similarly under threat.

“With warming global temperatures and most sea turtle populations naturally producing offspring above the pivotal temperature, it is clear that climate change poses a serious threat to the persistence of these populations,” the research concludes.

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