Global non-profit The Nature Conservancy has announced a $1.6 billion plan to help save and restore the world's oceans by selling "blue bonds" to coastal and island countries.

The Blue Bonds for Conservation initiative will refinance and restructure debt for coastal and island countries, so long as those nations commit to protecting at least 30 percent of their near-shore ocean areas, including coral reefs, mangroves and other important ocean habitats.

In exchange for enhanced ocean protections, TNC says the Blue Bond will give nations better terms for debt repayment and support with ongoing conservation work.

TNC says it already has secured more than $23 million in funding from donors towards the $40 million required to kickstart the scheme — which it is hoped eventually could unlock $1.6 billion in ocean conservation funding. Over the next five years, it plans to deliver Blue Bonds in up to 20 countries, protecting an additional 1.5 million square miles of the most biodiverse ocean.

"There's still time to reverse decades of damage to the world's oceans before we hit the point of no return," said Mark Tercek, CEO of TNC. "It's going to take something audacious to tackle marine protection at this scale, which means thinking beyond more traditional approaches to ocean conservation."

There's still time to reverse decades of damage to the world's oceans before we hit the point of no return. It's going to take something audacious to tackle marine protection at this scale. Unless the world can curb carbon emissions and successfully tackle ocean pollution, scientists predict 90 percent of the world's coral reefs will have died by 2050. As well as preserving marine life, protecting ocean habitats is also widely seen as essential for combatting climate change; mangrove forests sequester four times more carbon than rainforests.

Once a nation has accepted the offer of a Blue Bond, marine scientists at TNC will create a "marine spatial plan" to pay for the new marine protected areas and other conservation programs, using savings from debt restructuring and philanthropic donations, TNC said. Spending will be controlled by a trust independent of the government of the nation.

TNC estimates the scheme could be applied in up to 100 countries. "This is the philanthropic opportunity of a lifetime," said Tercek. "Every dollar we raise will result in 40 times the impact. It's hard to find better leverage than that."

The move comes just days after Greenpeace launched a major new campaign to ensure 30 percent of the world's oceans are officially protected by 2030.