A new United Nations assessment of ocean health documents a “deepening crisis” as climate change, pollution, overfishing, and biodiversity loss threaten marine ecosystems crucial to human survival.
The result is rising sea levels, acidifying seas, dying coral reefs and declining fish stocks that supply 20% of the animal protein humans consume, according to the report released Monday and compiled by 600 scientists from 86 nations. It’s the third World Ocean Assessment since 2015 and was last updated in 2021.
“The coming decade is decisive: without rapid, coordinated global action, ocean health will continue to decline, threatening climate stability, biodiversity resilience, food security, livelihoods and the well-being of billions,” Ian Butler, a lead author of the assessment and a marine ecologist with the Australian government, said in an email.
The assessment estimated that up to 45% of global economic activity takes place on the world’s coasts and that 3 billion people live within 100 kilometers (62 miles) of the ocean.
“Contamination and pollution, such as plastic waste, agricultural run-off, sewage and chemicals, are major contributors to the decline in ocean health,” stated the 1,352-page report. Those pollutants, meanwhile, are accumulating in marine organisms, their effect magnified up through the food chain to animals eaten by people.
About 38% of global fish stocks in 2021 were being harvested faster than populations could replenish themselves, up from 35% two years earlier, according to the latest available data.
Adding to the stress on fisheries are the impacts from climate change, which are decimating coral reefs that provide habitat for 25% of marine life. One-sixth of ocean heat absorption over the past 70 years occurred just between 2018 and 2023, according to the assessment. Hotter sea surface temperatures have spawned more destructive hurricanes and tropical cyclones and prompted some marine species to migrate to cooler waters, disruptinglocal fisheries.
The scientists said the rapid warming of oceans is also responsible for 30% to 50% of sea level rise, endangering coastal communities. As water heats up, its volume expands. Between 2013 and 2023, global sea level rise was 4.3 millimeters annually, compared to 2.1 mm per year from 1993 to 2002.
While the pandemic temporarily reduced stress on oceans as economic activity slowed, the industrialization of marine ecosystems continues, the researchers said, with planned deep sea mining operations posing potential risks to seabed ecosystems.
Although the assessment was wide-ranging, the researchers acknowledged that much remains unknown about the ocean, noting that only 27% of the global seabed has been mapped. The report is being released as the Trump administration moves to dismantle the world’s most extensive network of ocean sensors and observation platforms.
Read More: Trump Scraps Ocean Sensors Providing Crucial Data on Climate, Flooding
“Little of the vulnerability of marine biodiversity, species genetics and microbial communities, particularly in the deep sea, to climate change and emerging economic activities is understood,” the report states.
Still, Butler said there was reason for optimism, noting the ratification of the UN high seas biodiversity treaty last year that allows for the creation of marine protected areas in international waters.
“I believe with urgent, coordinated global action we still can restore its health to secure a healthy, biodiverse ocean which would benefit all life on Earth,” he said.
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Climate Change
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