The UN convention on the law of the sea sets out the legal framework for all activities in the ocean and seas. Upholding UNCLOS is central to the UK Government’s approach to ocean issues as an essential enabler of global security, growth and a healthy planet.
UNCLOS sets out the legal basis on which states can establish the baselines along their coasts, or joining points on their coasts, from which they are entitled to generate maritime zones, including their territorial sea and exclusive economic zone.
When UNCLOS was drafted, significant sea level rise and changes in coastlines as a result of the climate crisis were not contemplated by the drafters, and no provision was made for this. However, with sea level rise, coastlines are likely to regress, and some features may be completely inundated and lost.
The International Law Commission is the UN body of international law experts responsible for studying and making recommendations to encourage the progressive development and codification of international law. ILC work on the topic of sea level rise in international law has been ongoing since 2019, and the UK has responded to ILC requests for information on state practice. On 6 August 2021, the Pacific Islands Forum made a declaration to the effect that having, in accordance with UNCLOS, established and notified their maritime zones to the UN Secretary-General, Pacific Islands Forum members intend to maintain these zones without reduction, notwithstanding climate change-related sea level rise, and will not review or update the baselines or outer limits of their maritime zones as a consequence of climate change-related sea level rise. The Alliance of Small Island States made a similar statement in their leaders’ declaration in September 2021.
Having considered the work of the ILC to date on the issue of maritime boundaries, and the views of our partners, I can confirm that the UK Government take the view that UNCLOS imposes no express or affirmative obligation on states to keep their baselines or the outer limits of maritime zones derived from them under review, or to update them once they have been established in accordance with UNCLOS. UNCLOS provides that baselines and outer limits of the maritime zones are as shown on the relevant chart or specified by co-ordinates. It does not expressly require coastal states to update those charts or co-ordinates. This position is consistent with the object and purpose of UNCLOS as a regime for securing a stable division of maritime space. Once a state has established its maritime zones in accordance with UNCLOS, it is permitted to maintain those maritime zones, and the rights and entitlements that flow from them, notwithstanding changes to coastlines and physical features that result from sea level rise caused by the climate crisis. This does not prejudice the UK Government’s position on other international law questions raised by sea level rise that the ILC is also considering.
The UK Government’s position is that this analysis can only apply to baselines or outer limits which are initially established in accordance with UNCLOS. It remains the UK Government’s position that UNCLOS provides the complete and definitive rules on the drawing of baselines from which maritime zones are measured.
While the UK Government recognise that UNCLOS does not require states to update the relevant charts or co-ordinates designated by states as depicting the baselines and outer limits of their maritime zones, the UK Government consider it important that necessary hydrographic surveying takes place and navigational charts and other information continue to be updated as frequently as necessary for the purposes of navigational safety.
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