The sanctuaries, which Greenpeace says could be established by 2030, would protect species from the damages of overfishing, fossil fuel drilling projects and pollution.

"The '30x30' report puts forward a credible design for a global network of marine protected areas in the high seas based on knowledge accumulated over years by marine ecologists on the distribution of species, including those threatened with extinction, habitats known to be hotspots of biodiversity and unique ecosystems," said Alex Rogers, a professor at Oxford who co-authored the report.

Greenpeace published an interactive map as a companion to the study, showing how little ocean life is currently protected compared with the wide swaths of ocean that could be protected with its proposed network of protected areas.

Oceans cover 70 percent of the planet's living space and include 89 million square miles which are completely unprotected because they lie outside of national borders — currently, just two percent of the world's oceans are protected. Greenpeace's plan to establish conservation zones in 30 to 50 percent of the oceans would help ocean ecosystems recover from decades of worsening plastic pollution, overfishing, fossil fuel drilling and acidification brought on by increased carbon in the world's atmosphere.

"The speed at which the high seas have been depleted of some of their most spectacular and iconic wildlife has taken the world by surprise," said Callum Roberts, a marine conservation biologist at the University of York. "Extraordinary losses of seabirds, turtles, sharks, and marine mammals reveal a broken governance system that governments at the United Nations must urgently fix."

The study took into account the socio-economic impact the sanctuaries would have on global fishing industries, showing that "networks representative of biodiversity can be built with limited economic impact."

As delegations gathered in New York to discuss a treaty aimed at protecting oceans, Greenpeace urged world leaders to consider the groundbreaking 30x30 study as a guide for how to ensure a healthy future for marine life as well as the entire planet.

"The negotiations taking place here at the UN are crucial because, if they get it right, governments around the world could secure a Global Ocean Treaty by 2020 which has the teeth to realize a network of ocean sanctuaries, off-limits from harmful human activities," said Dr. Sandra Schoettner of Greenpeace. "This would give wildlife and habitats space not only to recover, but to flourish. Our oceans are in crisis, but all we need is the political will to protect them before it's too late."