From Puntarenas to Nice, coastal cities face escalating risks from sea level rise and shoreline erosion. The Third United Nations Ocean Conference (UNOC3), hosted by France and Costa Rica, will spotlight these urgent challenges and promote global collaboration for ocean sustainability.
UNOC3: A Shared Agenda for Sustainable Ocean Management
From 9 to 13 June 2025, in Nice, the Third United Nations Ocean Conference (UNOC3) will bring together policy makers, scientists and international institutions. Co-hosted by France and Costa Rica, the conference aims to promote science progress and global governance to ensure a sustainable future of the ocean.
Topics covered across UNOC3 and the Pavilion will range from marine biodiversity and pollution to ocean data integration and modelling. Coastal resilience will be a key theme, focusing on localised impacts of sea level rise and erosion. While coastal regions vary widely, the cases of France and Costa Rica offer distinct but complementary examples of climate challenges and responses.
Coastal Erosion in Nice, France
Nice, the host of UNOC3, is an emblematic case of the challenges affecting the Mediterranean coastal areas, where the impacts of sea level rise and sediment loss are already reshaping local landscapes. Nice’s coastal airport faces increasing flood risks as sea levels climb.
Further, the Côte d’Azur’s iconic pocket beaches – small crescent-shaped sandy beaches bounded by rocky formations – are vanishing. These beaches, essential to local biodiversity and tourism, have lost roughly 50% of their surface area since the late 19th century, according to the International Union for Conservation of Nature (IUCN). This erosion compromises natural buffers against storm surges, endangering urban infrastructure.
The city of Nice, along with its coastline, is featured at the centre of this Copernicus Sentinel-2 image acquired on 23 August 2024.
The EU Digital Ocean Pavilion will showcase the latest developments in sea level monitoring applied to informed coastal planning during a dedicated session on Wednesday 11 June, including a demonstration of the new COCLICO platform. This tool provides projections of sea level rise under different climate scenarios across Europe. A panel led by Mercator Ocean International will also explore nature-based solutions to enhance coastal resilience and climate adaptation.
Coastal Ecosystems at Risk in Puntarenas, Costa Rica
Puntarenas, located on a narrow peninsula along Costa Rica’s Pacific coast, presents a different but equally urgent case. The World Bank estimates that a 1-metre rise in sea level could inundate 90% of the city’s dry land, extending flooding up to 500 metres inland.
Beyond urban infrastructure, the region’s mangrove forests – crucial to coastal stability, marine biodiversity, and water quality – are increasingly threatened. These ecosystems are sensitive to changes in tidal patterns caused by sea level rise and require careful management to ensure their survival.
The city of Puntarenas, Costa Rica, and the mangroves on the surrounding coast are visible in this Copernicus Sentinel-2 image acquired on 2 May 2025.
Understanding where and how these ecosystems are changing is essential to managing and restoring them effectively. The EU Digital Ocean Pavilion will host a session on Friday 13 June focussed on practical solutions and best practices for addressing coastal challenges. The session will include innovative approaches to coastal monitoring, including new methods which leverage remote sensing data to map vulnerable ecosystems such as mangroves.
Furthermore, Copernicus Marine, implemented by Mercator Ocean International, supports Costa Rica’s monitoring capabilities through the Ocean Prediction for Costa Rica (OP4CR) initiative. Launched in March 2025, OP4CR provides tailored ocean forecasting services, including for the remote Cocos Island National Park and its rich biodiversity. The project will be showcased at the Pavilion on 10 June.
UNOC3: Supporting Coastal Adaptation in a Changing World
The experiences of Nice and Puntarenas illustrate the diverse but related coastal climate impacts from the erosion of Mediterranean beaches to the degradation of tropical mangroves. Addressing these interconnected challenges requires reliable data, state-of-the-art science, and informed policies.
UNOC3 and the European Digital Ocean Pavilion will be pivotal platforms to share scientific progress and exchange best practices, enabling more effective mitigation strategies in a time of rising seas.