The vast majority of green sea turtles in the northern Great Barrier Reef are now female because of warmer temperatures due to climate change, which influences their sex during incubation, researchers said Monday.

The population of about 200,000 nesting females in the area along the east coast of Queensland, Australia, is one of the largest in the world, and could crash without more males, according to the report in the journal Current Biology.

The temperature at which eggs incubate determines the sex of the eggs. Warmer nests, which are dug into beaches, mean more females. Just a few degrees can mean the difference between a balanced and skewed sex ratio.

"With average global temperature predicted to increase 4.7 Fahrenheit (2.6 Celsius) by 2100, many sea turtle populations are in danger of high egg mortality and female-only offspring production," said the report.

Since figuring out the sex of buried eggs is too difficult, researchers decided to catch sea turtles and use genetic tests to find out where they'd come from.

They worked in an area where two different populations of green sea turtles (Chelonia mydas) forage -- one from a warmer area and the other from a cooler area.

After collecting 411 for analysis and release, they found a "moderate female sex bias" in turtles from beaches in the cooler, southern Great Barrier Reef, where about 65-69 percent were female.

But those in the warmer, northern Great Barrier Reef were "extremely female-biased," at 99.1 percent female among juveniles and 99.8 percent for those between juveniles and adults.