Ocean governance took centre stage at COP30, with particular focus on the landmark ‘High Seas Treaty’. Professor of International Law Tim Stephens, and PhD candidate Thomas Chan are exploring how this major global reform could reshape the future of our oceans.
Professor Stephens is a leading expert in international law, researching sustainable ocean governance. His research reveals how gaps in international frameworks have impacted upon the oceans and polar regions. His published work focuses on the international law of the sea, international environmental law and international dispute settlement.
“The oceans absorb most excess heat from the atmosphere and around 30% of our greenhouse gas emissions, while the poles are the Earth’s ‘refrigerators’, influencing essential ocean currents and reflecting solar radiation back into space,” Professor Stephens says.
“There is no global forum where climate impacts on the oceans such as marine heatwaves and ocean acidification attract the attention they deserve so that governments can work on solutions.”
However, on 17 January 2026 this will change with the entry into force of the ‘High Seas Treaty’, which provides a legal architecture for protecting marine biodiversity beyond national jurisdiction.
Whilst the Treaty was adopted in June 2023 and opened for signature that same year, it only became a legally binding agreement after being ratified by 60 countries. Australia was a founding signatory of the Treaty and is expected to ratify the agreement soon. With the Treaty in full effect in 2026, do we have cause to be optimistic?
The ocean is finally receiving the attention it deserves as the most important component of the global climate system.
Professor Tim Stephens
What is the High Seas Treaty?
Professor Stephens explains the High Seas Treaty marks a historic milestone in global ocean governance, introducing measures that could transform how we protect and share marine living resources.
“The High Seas Treaty is something of a misnomer,” Professor Stephens says. “It’s actually called the 'Agreement on Marine Biological Diversity of Areas beyond National Jurisdiction’, or BBNJ Agreement for short.”
"This is a mouthful, and while it does emphasise that the BBNJ Agreement is not a truly comprehensive system for protecting the high seas, it does mark a major shift in the way the global community sees the oceans.”
The Agreement aims to promote equitable access to, and sharing benefits from, exploiting marine genetic resources on the high seas.
“The Agreement also, for the first time, provides a sophisticated system for the creation of high seas marine protected areas,” Professor Stephens says.
“This is one of its most important features, and could be utilised to improve high seas biodiversity conservation more generally and achieve the global target to protect 30% of the world’s coastal and marine areas by 2030.”
He further explains the Agreement also introduces a new requirement for environmental checks on activities with major impacts on the ocean. For the first time, projects on the high seas will need to undergo proper assessment, ensuring greater accountability and protection for marine ecosystems.
The BBNJ Agreement is a substantial reform and comes not long after the International Tribunal for the Law of the Sea (ITLOS) delivered its landmark Advisory Opinion on the duties of states to protect the marine environment from climate change under the UN Convention on the Law of the Sea (UNCLOS). ITLOS found that all states are under a stringent due diligence obligation to reduce greenhouse gas emissions, eventually preventing such pollution from occurring at all.
PhD student Thomas Chan, reiterates the importance of BBNJ discussions at COP30 from a global net zero point of view.
“The discussion of the BBNJ Agreement at COP30 builds on other work under the UNCLOS to position UNCLOS as a mechanism for climate change action,” Chan says.
“Incorporating UNCLOS and the BBNJ Agreement into global climate discussions is a crucial piece of the puzzle to achieving global emissions reduction, climate and biodiversity targets.”
“As an agreement focused on areas beyond national jurisdiction, the BBNJ is uniquely positioned to recognise the role of the oceans in the climate space in a way that national commitments by States (such as NDCs) cannot address.”
But, what are the complications?
The BBNJ Agreement is drafted so as not to undermine existing frameworks, such as regional fisheries management organisations (RFMOs). However, the relationship between the BBNJ Agreement and RFMOs is likely to be complex and uncertain for some time.
Possible complications include:
Overlapping mandates
- The BBNJ Agreement focuses on conserving marine biodiversity in areas beyond national jurisdiction, while RFMOs primarily manage fish stocks.
- Their responsibilities intersect when biodiversity measures affect fisheries, creating potential conflicts over authority.
Different governance structures
- RFMOs are region-specific and operate under existing international frameworks, whereas the BBNJ Agreement introduces a global governance layer. Aligning regional rules with global standards will take time and negotiation.
- Not all countries that are parties to the BBNJ Agreement are members of every RFMO, and vice versa. This mismatch can lead to inconsistent implementation and enforcement across regions.
Unclear legal hierarchy
- It is uncertain whether BBNJ provisions will override RFMO decisions or simply complement them.
- This ambiguity could lead to disputes over which rules take precedence in managing marine resources
Despite these challenges, Professor Stephens contends that the Agreement is bringing much‑needed attention to ocean governance and helping to spur urgent action.
“The ocean is finally receiving the attention it deserves as the most important component of the global climate system, and the onus is on all governments to ensure that the opportunity presented by the BBNJ Agreement as a springboard for urgent action to improve ocean protection is not missed," Professor Stephens says.
Manual Name : Professor Tim Stephens
Manual Description : Sydney Law School
Manual Address :
Manual Addition Info Title :
Manual Addition Info Content :
Manual Type : profile
_self
Auto Type : contact
Auto Addition Title :
Auto Addition Content :
Auto Name : true
Auto Position : true
Auto Phone Number : false
Auto Mobile Number : true
Auto Email Address : true
Auto Address : false
UUID :