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Report:
High Seas Treaty Offers Historic Opportunity for Climate Adaptation

As soon as next year, the ocean’s vast international waters could — for the first time — have rules for comprehensive biodiversity protection, once the widely anticipated UN High Seas Treaty secures the 60 national ratifications needed for it to enter into force. As nations convene later this month to determine the institutions and processes needed to implement the Treaty, a coalition of conservation scientists stress in a new paper the importance of also accounting for the specific challenges posed by the climate crisis.

The “high seas” — all international waters and seafloor outside any one country’s jurisdiction — is an area still not fully known to science. It comprises two-thirds of the world’s ocean and is one of the largest reservoirs of biodiversity on Earth — providing migratory routes for species including whales, sharks and tuna and hosting unique deep-sea ecosystems. However, only 1 percent of these waters are fully protected. The need for protections throughout the high seas is essential to meeting global sustainability goals such as the Convention on Biological Diversity’s Global Biodiversity Framework and its targets — including protecting at least 30 percent of the ocean by 2030 (30x30).

To save the high seas, plan for climate change — by authors from Conservation International and partners — outlines how the High Seas Treaty on biodiversity beyond national jurisdiction (BBNJ) offers a unique opportunity to factor climate-driven marine changes into its implementation framework. As governments prepare for the Treaty’s entry into force, the scientists pose critical questions that must be considered on how best to define and implement high seas Marine Protected Areas (MPAs) — particularly, for migratory species whose habitats and migration patterns are shifting due to warming waters, changing ocean currents and altered food webs.

“Protecting high seas biodiversity in the face of climate change is an ongoing chess game,” said Dr. Lee Hannah, Senior Scientist of Climate Change Biology at Conservation International’s Moore Center for Science and lead author of the paper. “Everything from whales to fish are moving to track warming waters. This ocean upheaval, due largely to climate change, can be addressed by the High Seas Treaty — which is why its swift ratification is so important.”

3 crucial steps ratifiers of the High Seas Treaty must take to effectively address climate impacts on species:

• collaborate with fisheries management and other high-seas organizations to conserve moving species;

• coordinate strategic plans for conservation networks across the high seas and national jurisdictions; and

• share and build scientific capacity across jurisdictions for modeling ocean-ecosystem dynamics and species movements in response to climate change.

The report points out each of these steps will help answer critical questions about how to demarcate MPAs for species that may soon shift outside of their current ranges, including those species that migrate vast distances across the ocean.

“We need to be thinking on two timelines at once — how the species in the high seas live now, and how they might live decades from now as climate change worsens,” Hannah said. “And of course, it’s made all the more complicated that no one country is in charge of the high seas — it’s a global group effort. But that’s why it’s so important to start planning now — so we have a solid roadmap by the time the Treaty has entered into force and is ready to be implemented.”

Currently, seven countries — Belize, Chile, Mauritius, Micronesia, Monaco, Palau and Seychelles — have ratified the High Seas Treaty and 90 have signed it, thereby signaling their intent to ratify. The High Seas Alliance is campaigning for at least 60 nations’ ratifications to be secured by the third UN Ocean Conference in June 2025.

“Our success in responding to the climate and biodiversity crises also depends on how we can adapt to a constantly changing environment,” said High Seas Alliance Director Rebecca Hubbard. “As governments gather this month to decide the processes to implement the Treaty, we have an important opportunity to factor in effective responses to marine protection and get ahead of the curve on climate change impacts in over two-thirds of the world’s ocean.”

Co-authors of the report include scientists from several member organizations of the High Seas Alliance — including Conservation International, BirdLife International and Oceans North — as well as Blue Nature Alliance, University of California Santa Barbara, Fisheries and Oceans Canada, Dalhousie University, Environment and Climate Change Canada, the German Federal Agency for Nature Conservation and the Swedish Agency for Marine and Water Management.

“We know that there are many marine species that are vulnerable to climate change. Planning for their protection as they change their distribution will be important in achieving commitments to protect biodiversity,” Susanna Fuller, VP of Conservation and Projects at Oceans North and a contributor to the report, pointed out. “Many of the pieces are already in place; but a concerted effort will be needed by scientists and governance bodies to manage new threats and implement new tools — including those envisioned under the High Seas Treaty.”