A green turtle hatchling emerges from the egg. This endangered species is one of seven sea turtle species David Pike

Rising sea levels pose a threat to turtle populations as shown by a study that looked into the effect of saltwater on the eggs.

Researchers from Australia's James Cook University found that turtle eggs submerged for one to three hours did not experience any significant level of mortality but longer periods of six hours and more saw a 40% rise in turtle embryo deaths.

This was due to low oxygen levels in seawater.

They analysed one of the largest green turtle populations in the world, on Raine Island to the northeast of Australia, near the outer edge of the Great Barrier Reef.

Here, only 10% of eggs produce turtles, compared to 90% in other parts of the world.

The endangered green turtle population here is also under threat from habitat loss, boats and pollution.

Dr David Pike, lead researcher of the project, said: "We are trying to anticipate the early effects. In some places it only takes a small rise in sea levels, when combined with a storm or a king tide, to inundate what had previously been secure nesting sites."

"We might be able to save them with people power," Pike said.

A 50cm rise in sea levels over the next 100 years from global warming could see the Raine Island washed away, he told The Guardian.

"A big concern worldwide will be trying to predict how sea level rises will impact sea turtle populations. It will take 20 to 30 years for us to realise that we don't have many adult turtles anymore, because the current hatchlings aren't making it."

The study is published in the Royal Society Open Science journal.

As many as 100,000 female green turtles reach the coral cay to lay eggs in the sand each summer.

Green turtles are one of seven sea turtle species, which include the loggerhead, the leatherback, the hawksbill, the Kemp's ridley, the Olive ridley and the flatback.

Incidentally, Australia is one of the countries that has persistently been ignoring pleas to curb its carbon emission which is among the world's highest when measured in per capita. Prime Minister Tony Abbott has ordered a stop to government funds for clean energy while endorsing coal-based power plants.

Australia has also repealed its carbon tax a few months ago, following which carbon emissions and electricity demand rose.