A month ago, thousands of diplomats, scientists and advocates gathered in New York City to reaffirm their support for ocean preservation at the first United Nations Ocean Conference. This week they’re back at the U.N., poised to take action on what would be one of the most important environmental treaties in a generation – an international accord to protect the biodiversity of the high seas through the creation of marine reserves and other actions.

The high seas – the huge swathe of the ocean beyond any nation’s jurisdiction – account for 58 percent of the marine environment and face the same threats as territorial waters: climate change, overfishing and plastic pollution. Yet the high seas are the Wild West of the ocean, largely far beyond the reach of the law when it comes to protecting increasingly imperiled ecosystems.

“It’s pretty much a free-for-all on the high seas,” said Peggy Kalas, coordinator of the High Seas Alliance, a coalition of 32 major environmental groups founded in 2011 to push for an international treaty to protect the biodiversity of the ocean.

The United Nations Convention on the Law of the Sea, which was signed in 1982 and went into force 12 years later, lays out the rules and responsibilities for nations’ use of the ocean. But the word “biodiversity” does not appear in the 208-page document. The treaty also provides no mechanisms to assess the environmental impact of fishing, mining and other activities or to protect the high seas in marine reserves, as countries are increasingly doing in the waters of their exclusive economic zones (EEZs), which extend 200 miles (320km) from shore.

“It was negotiated in the 1970s before we had the technology to go so far and so deep,” said Kalas. “The importance of a high seas biodiversity treaty is hard to understate. It will be a game changer for how the ocean is regulated in the future.

“It’s a Paris agreement for the ocean,” she added, referring to the international accord brokered in 2015 in which 195 nations agreed to reduce greenhouse gas emissions to stave off catastrophic climate change. “We want the type of global attention the Paris agreement has gotten.”

The United Nations in 2015 authorized a two-year “Preparatory Committee” process to hammer out the main elements of an ocean biodiversity treaty. The fourth and final “PrepCom” meeting is taking place over the next two weeks. The expectation is that it will end with a recommendation that the U.N. General Assembly convene what is called an Intergovernmental Conference (IGC) to negotiate the specific terms of the high seas biodiversity accord.

“We have no doubt whatsoever that we will be calling an Intergovernmental Conference,” Ambassador Juan Jose Gomez Camacho, Mexico’s permanent representative at the U.N., said Tuesday during a press conference at the PrepCom meeting. “This is not about anymore zero sum games but making sure that we all benefit. Oceans have to be a source of wealth, has to be a source of knowledge, and has to be above all a source to improve the quality of life for everybody.”

Lisa Speer, director of the international oceans program at the Natural Resources Defense Council in New York, said the hope is that IGC negotiations can conclude in 2019 rather than drag on for years as the climate change talks did.

“We have the advantage in this arena of having many, many years of decisions on these issues,” she said. “There’s consensus on broad strokes on what should be in the treaty agreement. But countries have been reluctant to engage in horse trading before they get to the IGC. You have a general sense of which areas where there will be a consensus but how hard people push and whether there is more or less consensus than appears is unknown.”

One potential tripwire: whether the high seas should be considered “the common heritage of mankind,” with the benefits to be shared among rich and poor nations, or whether a “freedom of the seas” ethos should prevail that places fewer restrictions on sustainable use of the ocean.

The PrepCom meetings have focused on the key “elements” that would be included in a treaty on “biodiversity of areas beyond national jurisdiction” (BBNJ in U.N.-speak). These include: the creation of marine reserves; the sharing of marine genetic resources – marine molecules, bacteria and algae that could be used in pharmaceuticals, cosmetics and other products; environmental impact assessments and when they must be conducted for high seas activities; and the transfer of marine technology to developing countries.

A document issued by the PrepCom chair on May 31 to guide the talks now under way outlined the general principles on those elements, such as transparency, the use of best available scientific evidence and a precautionary approach to avoid inflicting harm when insufficient information exists on the impact of a proposed activity.

But the final PrepCom talks will leave the details of achieving those aims to IGC negotiations. For instance, it’s unresolved who would propose the creation of marine protected areas on the high seas, how they would be reviewed and approved, who would manage the reserves and who would enforce restrictions on their use.

That’s crucial. For instance, a 1992 U.N. agreement to protect fish stocks on the high seas required a number of measures to minimize the impact of bottom trawling that were not enforced, according to Matthew Gianni, a cofounder of the Deep Sea Conservation Coalition. Advocates subsequently worked over a decade to persuade the U.N. General Assembly to pass a series of resolutions to require environmental assessments, closure of vulnerable fishing grounds and other measures. Still, noted Gianni during a presentation last year in advance of a PrepCom meeting, enforcement has lagged.

“It is important to follow through on international legal obligations,” he said. “Civil society pressure is critically important. Scientists, NGOs have a critical role to play.”

Advocates remain optimistic that momentum is building to finally push a high seas biodiversity treaty over the finish line.

“There are lot of countries that are now very involved in this,” said Speer. “That’s changed recently. People realize that it is going to happen.”