The primary objective of the Law of the Sea Convention is to codify a careful balance. On one side is coastal state sovereignty, sovereign rights, and jurisdiction in their maritime zones. On the other are the flag-state rights and duties in such zones, such as the rights of innocent passage through territorial seas and the freedom or right to fish in the high seas.

The negotiators of the convention at UNCLOS III — the third meeting of the parties under UN auspices — were addressing the tension of the over-exploitation of fish and seabed minerals through recognition of a new 200 nautical mile Exclusive Economic Zone, and new provisions regarding the marine environment, fisheries in the high seas, and seabed minerals in the regulated area. Unfortunately, the economic importance of commercial fisheries, particularly in the high seas, has continued to trump concerns about marine conservation.

My organization works on two existential threats to the ocean: acidification and plastic pollution. Neither of these is specifically mentioned in the convention. The treaty does not itself provide for the details for taking the collective action needed for a significant reduction in CO2 emissions leading to higher pH levels and of plastic that enters waterways. Why? Because the convention is more akin to a “Constitution for Ocean Governance” that sets out rights and duties that nations respect in negotiating more specific agreements. Unfortunately, these threats are growing concurrently with the ocean-harming effects of climate change, which is also not mentioned in the treaty text. To articulate solutions for a coordinated approach, we need new stand-alone agreements, or the incorporation of ocean acidification and plastic pollution into existing instruments.

I would argue that the sea treaty recognizes the legal duty of states to address these threats. This convention framework identifies the duties and responsibilities of conservation in managing living marine resources — and thus the protection of the integrity of the ocean environment — and establishes an expectation for national, regional, and international action and cooperation. As such, looking back we can see it was visionary, even if limited to the knowledge of the time — because we now know the ocean is not too big to fail, that its health is adversely affected by anthropogenic impacts, and those activities continue to reduce its abundance.

Like climate change, ocean acidification is caused by humanity’s carbon dioxide emissions, a third of which have been absorbed by the ocean over the past century. The resulting change in marine chemistry adversely affects every part of the food web, and thus both ocean productivity and its capacity to produce life-giving oxygen.

Plastic pollution is ubiquitous in the global ocean — from its deepest depths to the salt spray from the waves, as well as on every beach, and in every coastal marsh and mangrove forest. Microplastic has been found in virtually all forms of sea life. The threat posed by plastic to the integrity of the ocean has been established, as has the threat to the economic and social well-being of coastal communities.

In regard to international agreements, progress on plastic is much more advanced than ocean acidification. The 1972 London Dumping Convention prohibits the discharge of plastics (and other synthetic material) that will persist in the environment. Annex V of the International Convention for the Prevention of Pollution From Ships, or MARPOL, prohibits the discharge of all plastics into the ocean. These two instruments help get at the 10-20 percent of plastic in the ocean that comes from ships, but not the 80 percent that may be outside the scope of the ocean convention.

We have seen that action can be taken quickly when needed, as in the January amendment to the Basel Convention. The amendment governs the transboundary movement of plastic waste as a means of making the global trade in the material more transparent, and better regulated in regard to safety, human health, and the environment. It also recognizes the need for assisting developing nations, especially Small Island Developing States, from the effects of such plastic pollution.

The advent of a formal proposal for a global agreement to address the full lifecycle of plastic and prevent marine litter and microplastics pollution similar to the Paris climate agreement is supported by two-thirds of UN members, and is thus perhaps inevitable.

Ocean acidification may not be directly addressed under the existing climate change measures of the UN climate convention, the Kyoto Protocol, or the Paris Agreement. However, the 2019 Intergovernmental Panel on Climate Change report on the ocean and the cryosphere made the case for doing so. The Ocean Foundation and its partners have taken the lead on the development of legal and policy measures to address acidification at the subnational, national, and regional level. It is just a matter of time before this is inserted into existing instruments. Or, if it turns out we can articulate why a separate accord would be necessary and appropriate, or perhaps easier, the policy work could become a separate accord on ocean acidification.

Fortunately, the Law of the Sea Convention provides a strong legal foundation to address excess CO2 emissions and plastic as pollution to be prevented. The continuing strength of the treaty lies in its prioritization of the well-being of the global ocean. Thus, it provides the basis and framework for addressing future issues of concern that we have not yet envisioned.