The UK has agreed to transfer sovereignty of the largely uninhabited Chagos archipelago to Mauritius. The islands have been known as the British Indian Ocean Territory since being administratively detached in 1965 from what was then the colony of Mauritius. Except for the US military base on Diego Garcia at the southern tip of the archipelago, the islands have been uninhabited since 1973.
As Mauritius takes back control, there are big environmental implications.
These 247,000 square miles (640,000km²) of remote seas include among the most pristine tropical coral reef ecosystems on our planet. Chagos is nearly three times the area of the British Isles. In 2010, it became the world’s largest marine protected area that bans any form of fishing.
The shallow water coral reefs account for 1.5% of the global total. Like coral reefs elsewhere around the planet, the marine ecosystems of Chagos are threatened by climate change with rising sea levels and warming waters. Unlike most places, however, these reefs don’t currently face the extra stresses such as pollution and physical damage that come with the presence of people.
Whether the islands remain uninhabited is a major factor in the potential environmental repercussions of Mauritian sovereignty. Future scenarios are highly dependent on how the UK and Mauritius engage with the displaced Chagossian community.
Chagossians have long campaigned for a right to return to the islands and need to be part of future plans. This would require establishment of infrastructure and livelihoods. The UK government has previously explored resettlement options with detailed feasibility studies. Addressing possible resettlement will form an important part of how Mauritius takes forward management of the environment in Chagos.
The environmental consequences of a change in management and human activity could be good or bad. Any environmental benefits or damage will depend very much on what, if any, development takes place and how it is managed. The presence of people could cause damage, but it doesn’t need to.
Economic activity and infrastructure can support the capacity to do research and to take action to help habitats adapt to climate change. This could include, for example, transplanting strains of coral with better resistance to marine heatwaves.
Island restoration efforts that began when Chagos was a British territory could become much easier if facilitated from local settlements rather than relying on long-distance expeditions. This includes the removal of rats from certain islands to help ground-nesting birds. Rat eradication also helps the health of surrounding coral reefs. The presence of people as observers could help deter unregulated fishing from vessels sailing into these quiet waters.
There is substantial scientific research by people from around the globe, including from the Zoological Society of London, already taking place on the ecosystems of Chagos. This supports informed ecological management under the current administration.
The government of Mauritius needs to continue supporting this, including plans for a Mauritian marine protected area in Chagos. Limited settlement and different zones allowing some uses including fishing are proposed. Funding and support for Mauritius to grow its ability to manage these islands is promised in the sovereignty transfer announcement. This is vital for a future Mauritian administration to be able to take forward environmental action.
Mauritius should embrace cooperation with the UK and other regional partners. The neighbouring Republic of Seychelles, for example, has extensive experience with the management of its own lightly inhabited outer islands, similar to those of the Chagos. Mauritius already cooperates with Seychelles in the world’s first joint management area of underwater extended continental shelf, the Mascarene plateau that covers approximately 150,000 square miles.
The announcement of an agreement to transfer sovereignty of the Chagos archipelago might end years of dispute between the UK and Mauritius governments over jurisdiction. But it marks the humble beginnings of what will be complex, difficult and important work. There will inevitably be disputes between the two countries and other people involved, not least Chagossian citizens, in how these globally important ecosystems are managed.
It is vital for the environment of Chagos that there is an effective handover. Approaching sovereignty transfer, Mauritius needs to continue the current level of environmental engagement. There may later be reintroduction of economic activities, such as limited commercial fisheries or the resettlement of people with potential tourism development.
Importantly, environmental outcomes can be successfully addressed whether people return or not. But this needs careful evidence-informed planning and robust management. And Mauritius needs to build effective working partnerships with the UK, Chagossians, scientists and the wider global community to deliver a sustainable future for the Chagos archipelago.
