Addressing Land-Based Marine Pollution
Water and waste naturally flow into rivers, lakes, and oceans – carrying with them pollutants that threaten ecosystems and human well-being. Each year, more than 11 million metric tonnes of plastic enter the seas , reflecting a broader challenge in which approximately 80 per cent of marine pollution originates on land .
UNEP works with countries and partners to reduce land-based sources of marine pollution through an integrated “source-to-sea” approach, linking land, freshwater, coastal, and marine management.
This issue is particularly severe in the Wider Caribbean and in Small Island Developing States (SIDS), where coastal and marine ecosystems are vital for livelihoods, tourism, and biodiversity, yet are increasingly threatened by climate change, biodiversity loss, and pollution.
Coastal regions are home to about 40% of the global population, yet only 15% of coastlines remain in a natural state. Freshwater, coastal, and marine ecosystems face growing pressure from habitat destruction, sedimentation, nutrient runoff from agriculture, plastic pollution, and untreated wastewater.
These pressures lead to eutrophication, habitat loss, and declines in biodiversity, and are exacerbated by gaps in data, monitoring, and scientific capacity. In many regions, particularly SIDS, limited ability to track and manage pollution sources hinders effective governance and threatens water security and public health.
The health of marine and coastal ecosystems is not only an environmental concern; these blue ecosystems underpin economies, communities, and the planet’s stability. The ocean economy contributes an estimated USD 3 – 6 trillion each year, supporting millions of livelihoods and sustaining. The ocean also acts as a vital buffer against climate change, absorbing over 90 per cent of excess heat and 30 per cent of human-induced carbon dioxide emissions. Protecting biodiversity in these ecosystems is essential to safeguard economic assets, support societies, and enhance planetary resilience.
Source-to-sea Approach
UNEP’s “source-to-sea” approach addresses these interconnected threats by promoting integrated management across systems, from land and freshwater to coastal and marine environments. This approach helps close critical gaps in data and monitoring equipping countries, particularly SIDS, with the tools and capacity to track and reduce pollution at its source.
Through this approach, UNEP supports countries in implementing regional agreements such as the Cartagena Convention and its Protocol on Land-based Sources of Pollution (LBS Protocol), strengthening governance and improving water quality.
A key example of a source-to-sea initiative is the Water Quality Capacity Development Initiative in the Wider Caribbean. This project operationalizes the Cartagena Convention’s Land-Based Sources (LBS) Protocol by fostering cross-sector collaboration and building sustainable capacity through a customized Learning Management System. The system standardizes water quality protocols, harmonize data, and enhances monitoring and reporting across countries.
By scaling such initiatives, UNEP ensures that improved data collection and upstream actions lead to effective governance and healthier coastal and marine ecosystems for all.
