Climate Change is Turning These Green Sea Turtles Female

Australia’s iconic Great Barrier Reef is home to one of the largest populations of green sea turtles on earth, but warming temperatures there linked to climate change are having a bizarre and worrying impact on them – they’re turning an alarming number of hatchlings female.

Unlike most animals, genetics don’t determine the sex of sea turtles. Instead, the temperature of the eggs while they’re incubating does, in what’s otherwise known as temperature-dependent sex determination. The warmer the temperature, the more likely it is that developing embryos will be female, and it only takes a few degrees to make a difference.  At about 85 degrees Fahrenheit, nests typically produce an equal amount of males and females. If it’s a little bit cooler, there will be more males; if it’s a little bit warmer, there will be more females.

According to a new study, which was just published in the journal Current Biology, warming temperatures are skewing the sex ratios at an alarming rate in the Great Barrier Reef, and that’s a big problem.

For the study, scientists collected blood and skin samples from two genetically distinct populations of green sea turtles, which allowed them to figure out individual sex, in addition to where they were born.

They found that populations, who live on cooler beaches in the South were only about 65 to 69 percent female. When they looked at populations in the North, more specifically around Raine Island where about 200,000 sea turtles nest, they found that 99.1 percent of juveniles were female, 99.8 percent of subadults were female, and that 86.9 percent of adults were female.

When those results were combined with temperature data taken since 1960, they found that green sea turtle rookeries have been producing mostly females for more than two decades, and estimated that a completely female population is possible in the near future.

Scientists added in the study that with temperatures predicted to increase by several degrees in just a few generations of turtles, they’ll have very little time to adapt to a rapidly changing climate. While their population size may seem fine now, and a few males can fertilize a lot of females, the growing lack of males could ultimately lead to their extinction.

“This research is so important because it provides a new understanding of what these populations are dealing with,” said Dr. Michael Jensen, lead author of the study from the National Oceanic and Atmospheric Administration. “Knowing what the sex ratios in the adult breeding population are today and what they might look like 5, 10 and 20 years from now when these young turtles grow up and become adults is going to be incredibly valuable.”

They hope to learn more about how species who have temperature dependent sex determination are dealing with climate change, in order to implement the most effective conservation strategies.

The good news is that there’s still time to help sea turtles in the Great Barrier Reef, and in other places where they may need even more help. The young females are still years away from reaching an age where they’ll reproduce, and measures can be taken now to help them, such as shading key spots on beaches where they nest.

“Finding that there are next to no males among young northern green turtles should ring alarm bells, but all is not lost for this important population,“ said World Wildlife Fund-Australia CEO Dermot O’Gorman. “Scientists and wildlife managers now know what they are facing and can come up with practical ways to help the turtles.”

Photo credit: Thinkstock


Leanne K
Leanne K8 hours ago

You would assume Australia would be devastated by the dreadful impact global warming has had on our Great Barrier Reef and committed to doing everything possible. Um no, it would appear. Its barely rated a mention. Unreal. Add it to that long long list of things Australia ought to be shamed by, yet isnt. You know the one - our decimation of our Aboriginals, Terra Nullus, the Stolen generations, aboriginal deaths in custody, aboriginal suicide, the White Australia policy, culling of kangaroos and brumbies, oh jeez our horrid live export, treatment of asylum seekers- sending them to the Woomera or Port Headland followed by off shore processing Nauru and Manus. A nation built on suffering

Leanne K
Leanne K9 hours ago

Nothing wrong with being a girl. Be terrific if it helps their numbers

Ruth S
Ruth S17 hours ago


David C
David Cyesterday


Dana W
Dana Wyesterday

Thanks for sharing

Henry M
Henry M1 days ago

If the excrement of humans who use birth control enters waterways, it can result in male fish becoming female, decreasing the number of breeding pairs, and thus, population.

Danii P
Danii P2 days ago


Ellie M
Ellie M2 days ago


Winn A
Winn A2 days ago


Ruth G
Ruth G2 days ago

Continuing daily tragic evidence on the effects of climate & yet trump & otheres continue to ignore