Severe’ stress on oceans as rate of sea level rise doubles in 10 years, UN warns | Oceans

The United Nations’ third World Ocean Assessment reveals that global oceans are under “severe and accelerating” pressure from human activities. Key findings show sea-level rise more than doubled to 4.3mm per year by 2023, while 52.1 million tonnes of plastic enter the seas annually, threatening over 4,000 marine species according to the report.

Why is the rate of sea-level rise accelerating?

Sea levels are climbing at an increasing pace. According to the UN assessment, the rate rose from 2mm a year prior to 2015 to 4.3mm a year in 2023.

This acceleration coincides with massive heat absorption. The ocean has already absorbed 90% of the excess heat and 30% of the carbon dioxide released by burning fossil fuels.

Notably, 16% of the increase in global ocean heat since 1955 occurred after 2018. The most significant warming was observed in the Atlantic Ocean and the southern regions of the Indian and Pacific Oceans.

How is plastic pollution impacting marine biodiversity?

The report calculates that 52.1 million tonnes of plastic enter the ocean every year. This pollution contributes to an estimated 24.4 trillion microplastic particles currently in the seas.

These particles impact more than 4,000 marine species. Industrial fishing and pollution are described as “intensifying” stressors that lead to widespread biodiversity loss.

Rafael González-Quirós, joint coordinator of the expert group, stated that the need for a resilient ocean has never been more urgent given the profound changes these ecosystems are undergoing.

What is driving the strain on ocean systems?

Human population growth is a primary driver. The global population grew from 7.7 billion in 2017 to 8.2 billion by late 2024.

This growth puts direct pressure on coastlines. More than a third of the population lives within 100km of coasts, and 11% live on land less than 10 metres above sea level.

Other factors include technological advances, geopolitical instability, and changing governance structures. These cumulative anthropogenic pressures have put ocean systems under “severe strain.”

What happens next for ocean protection?

Global efforts could shift toward creating “fully protected ocean sanctuaries.” Greenpeace is calling on governments to close vast areas of the ocean to extractive human activities, including deep-sea mining and industrial fishing.

Governments have promised to protect 30% of the world’s ocean by 2030. This is the minimum level scientists say may be required for the ocean to recover.

Future stability may depend on strengthening coordination. While the landmark high seas treaty and 56 other treaties have improved resource management, UN Secretary General António Guterrez warned that the world cannot treat the ocean as limitless.

Frequently Asked Questions

What is the current rate of sea-level rise according to the UN?
The rate was 4.3mm a year in 2023, up from 2mm a year prior to 2015.

How many microplastic particles are estimated to be in the oceans?
There are an estimated 24.4 trillion microplastic particles in the seas.

What percentage of the ocean’s floor has been mapped by 2025?
Only 27% of the ocean floor has been mapped.

Do you believe international treaties are enough to reverse the damage to our oceans?