Earth’s vast oceans cover over 70% of its surface, and play a key role in regulating our planet’s climate. However, the bulk of our oceans are deemed “high seas,” and lack a comprehensive approach to protecting our common interest therein. A new Global Ocean Treaty may soon begin to address this gap in international law.

International custom over the oceans began with the Freedom of the Seas doctrine, which emerged in the early 17^th century when Dutch navigation rights were asserted in Portuguese territorial waters. The resulting doctrine limited national rights to a narrow sea-belt surrounding a nation’s coastline (“imperium terrae finiri ubi finitur armorum potestas,” meaning the dominion of land ends where the power of arms ends, which translated to the limit of a cannon shot); the remainder of the oceans were deemed free for all. This principle — based on an assumption of inexhaustible abundance — enabled the ocean’s resources to be exploited as common property. However, problems emerged after the Second World War as demand for ocean resources amplified.

A change in the tide occurred in 1967, when UN members were urged to come to an agreement on fair and responsible use of the world’s oceans. Some 15 years later, agreement was reached on the UN Convention on the Law of the Sea (“LOSC”), which set limits on how much ocean a nation could claim as its own, and confirmed that high seas (covering the ocean beyond Exclusive Economic Zones) remained outside any national jurisdiction (i.e., are “the common heritage of all mankind”). Within the high seas, states retained the right to conduct activities for peaceful purposes.

Natural resources in the high seas remained a complicated matter. While LOSC permits all States to exploit marine life, it also encourages cooperation to conserve resources and ensure their sustainability. However, lack of enforcement of international law at the high seas, along with the inability of LOSC to adequately deal with current challenges (such as overfishing, plastics pollution, and climate change), highlights the failings of LOSC for current times.

Climate change, in particular, challenges effective implementation of LOSC. Healthy oceans play a critical role in regulating global climate by shielding earth from solar radiation, producing oxygen, storing heat, and absorbing anthropogenic CO₂. The absorption of that excess carbon, however, acidifies our oceans by lowering the water’s pH, thereby killing marine habitat and harming marine life. Fishing has exacerbated the impacts; nearly 90% of the world’s marine fish stocks are now fully exploited, over-exploited, or depleted. Climate change will further impact these populations, on which some three billion people depend on for their immediate nutrition.

What can be done to protect our common interest in our oceans? LOSC was negotiated before climate change had global attention. Concurrently, the United Nations Framework Convention on Climate Change, which came into force in 1994 (the same year as LOSC did), largely focuses on land-based mitigation and adaptation. The 2015 Paris Agreement offers little more, as it mentions the ocean only once, in its preamble.

Targeted initiatives are however underway. In 2015, the UN General Assembly adopted a resolution to develop a legally binding agreement for conservation of marine life beyond national waters. The corresponding Global Ocean Treaty could require environmental impact assessments, management and conservation capacity building, international sharing of benefits from marine genetic resources, and use of area-based management tools, including marine protected areas. Scientists have urged that a target of protection of 30% of the world’s oceans by 2030 is crucial to increase resilience and help mitigate the impacts of climate change. This therefore represents an historic opportunity to advance governance over marine conservation and sustainable use of marine resources, and thereby protect our common ownership interests and corresponding duties of care owed to our valuable oceans.