The ocean economy is expanding at a breakneck pace, but failing to respect natural boundaries puts million of jobs and vital habitats at immediate risk.

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This article is part of a three-part series on the blue economy. Check out part 1 – Mapping the Blue Economy: Sectors, Policies, and Challenges Amid Climate Change – and stay tuned for part 3, coming in July.

The blue economy refers to the sustainable use of ocean resources for economic growth, improved livelihoods and ecosystem health. It relies on the ocean’s ability to provide goods and services to humanity and on the skills of economic agents to extract and harness these services.

If the ocean economy were a country, it would rank as the world’s fifth-largest economy. Yet, the scale of economic value underscores a critical truth: oceans, like all ecosystems, have limits. When the pursuit of growth ignores these natural boundaries, unchecked extraction and exploitation push marine systems beyond their carrying capacity, eroding biodiversity, magnifying pollution and intensifying climate risks.

Ocean Health

The Ocean Health Index (OHI) is a scientific framework that assesses ocean health by measuring how sustainably marine ecosystems deliver 10 key benefits to people – including food, coastal protection, and biodiversity – scored from 0 to 100. A higher score indicates a healthier, more sustainable ocean ecosystem. 

In 2025, the global average stood at 72, a two-point increase from the previous year and a “rebound” from pandemic-era lows, although still below the pre-pandemic average of 75.

While the general outlook for ocean health remains positive, there are areas in dire need of intervention. Fish stocks, for example, are poorly managed, and we are missing out on sustainable seafood farming opportunities. With regards to biodiversity, the low score for iconic species suggests that several local species of cultural importance are already at a heightened risk of extinction, underscoring the urgent need for conservation. 

Marine Biodiversity and Pressures

Ocean biodiversity faces critical pressures, primarily from climate change, pollution, overfishing, and habitat destruction. Because of these stressors, over half of all marine species may be extinct by 2100. Over the past several decades, around half of all salt marshes, 35% of mangroves, 30% of coral reefs, and 29% of seagrass meadows have been lost or severely degraded worldwide. Oyster reefs have fared even worse, with global losses estimated at up to 89%. Meanwhile, only 8.4% of the world’s oceans are designated as protected areas.

Climate change is also altering the distribution of species. Oceans naturally act as a climate buffer, absorbing heat and carbon dioxide (CO2) from the atmosphere. But with oceans warming, marine heatwaves are becoming more frequent. Combined with changes in the use of ocean resources, warm waters have caused ecosystems to degrade and several species to lose their home. Research suggests that 17% of the world’s marine animal biomass could disappear by 2100 if CO2 emissions continue at the current rate. On the other hand, if warming is limited to a 2C rise above pre-industrial temperatures, the maximum threshold set in the Paris Agreement, then the severity of marine mass extinction could be cut by more than 70%.

Marine plastic pollution represents another huge challenge for the oceans’ health. Some 19-23 million tonnes of plastic waste leak into aquatic ecosystems every year. Plastics impact marine life across the entire food chain, both physically and chemically, through the toxic compounds they release. Tiny plankton can absorb microplastics, which interfere with their growth and reproduction. Small fish that feed on plankton ingest these particles, often experiencing digestive blockages or reduced energy. Larger species such as sea turtles may mistake plastic bags for jellyfish, leading to internal injuries or starvation. Even apex predators like dolphins and seabirds accumulate toxins from plastics through the prey they consume, which can disrupt their hormonal balance, impair reproduction, and alter natural behaviours such as feeding and migration.

Frequent oil spills, unchecked coastal development and dumping of industrial waste at sea present yet another problem for ocean health. In regions where governance is weak or enforcement is inadequate, illegal fishing, unregulated deep-sea mining and hazardous waste disposal often become rampant, accelerating the degradation of ocean habitats and undermining long-term sustainability. Deep-sea mining in particular is emerging as a major threat, driven by demand for minerals like cobalt and nickel. It disturbs fragile seabed habitats and generates sediment plumes that can smother marine life. Scientists warn that recovery from such damage could take centuries, if it happens at all.

More on the topic: Why We Need a Deep-Sea Mining Moratorium

These issues become all the more important in the face of a burgeoning ocean economy. Between 1995 and 2020, the ocean economy grew by 2.5 times, outpacing the growth of the broader global economy. Yet, this growth is a double-edged sword: without a transition to sustainability, the very sectors driving prosperity could collapse. 

Research indicates that failing to adopt a sustainable approach to using the ocean’s resources could endanger up to 40 million jobs compared to 2019 levels, particularly in fisheries, coastal tourism, and maritime transport. Job losses would stem from depleted fish stocks, declining coastal tourism due to environmental degradation, and disrupted maritime trade routes as climate impacts and ecosystem degradation affect transport infrastructure. 

Coastal Degradation and Resilience

Coastal zones cover just 4% of the Earth’s total land area and 11% of the world’s oceans, yet they are home to more than a third of the world’s population. Cities such as New York, Mumbai, and Shanghai owe much of their growth and connectivity to their coastal location. Human settlement and economic activity are often concentrated along coasts, making these regions vital. Coastal waters also underpin food security: roughly 90% of the world’s marine fish catch comes from nearshore environments. 

Located on the fringes between land and water, coastal zones are becoming increasingly vulnerable to climate change. These dynamic environs often bear the brunt of hazards such as floods and cyclones, which threaten both physical systems and socioeconomic systems. Coastal vulnerability studies have shown that tropical and subtropical regions – island nations like Seychelles, Fiji and Barbados – are more vulnerable to coastal hazards.

To reduce vulnerability, governments and communities are rolling out adaptation measures with growing urgency. Nature-based solutions, such as wetland and mangrove restoration, are being funded alongside structural defences like seawalls and smarter land-use planning, to strengthen coastal resilience. Of equal importance are policies that integrate local knowledge, community participation, and long-term monitoring to track progress. By investing in both ecological restoration and human preparedness, societies can safeguard coastal ecosystems while protecting the millions of people who depend on them for food, livelihoods, and cultural identity.