Rate of ocean warming doubled in 20 years, says UNESCO report

"All the alarm bells are ringing", said UNESCO Director General, as the State of the Ocean report was launched on Monday.
Ocean warming, acidification, sea level rise and deoxygenation are among the challenges faced, while sustainable aquaculture offers hope for future food security, according to the UNESCO report.

Ocean warming, acidification, sea level rise and deoxygenation are among the challenges faced, while sustainable aquaculture offers hope for future food security, according to the UNESCO report.

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A new UNESCO report has revealed critical data on the accelerating threats to the world's oceans.

The "State of the Ocean Report 2024," launched on Monday 3 June and supported by contributions from over 100 scientists from nearly 30 countries and backed by Iceland, presents a comprehensive review of challenges such as ocean warming, rising sea levels, pollution, acidification, de-oxygenation, blue carbon, and biodiversity loss.

"This UNESCO report shows that climate disruption is having an increasingly strong impact on the state of the ocean. Temperature, acidification, sea level: all the alarm bells are ringing," said Audrey Azoulay, UNESCO Director-General in a UNESCO press statement.

"In addition to implementing the Paris Climate Agreement, we call on our Member States to invest in the restoration of marine forests and to better regulate marine protected areas which are important reservoirs of biodiversity," Azoulay added.

Key challenges: ocean warming, sea level rise, oxygen decline and rising acidity

One of the main threats identified by the report is ocean warming, which has doubled over the past 20 years. In 2023, the ocean experienced one of the highest temperature increases since the 1950s. Ocean temperatures have risen by an average of 1.45°C above pre-industrial levels, with hotspots in the Mediterranean, Tropical Atlantic, and Southern Oceans exceeding 2°C.

The rate of sea level rise has also doubled in the past 30 years, contributing to a global increase of 9cm, the report says.

A third key area for concern is declining ocean oxygen levels, which the report notes impact not only wild habitats but also coastal communities that depend on fisheries and aquaculture, with the ocean losing 2% of its oxygen since the 1960s. Approximately 500 "dead zones" have been identified, where marine life is nearly non-existent due to low oxygen levels, the report states.

Rising acidity is the fourth threat identified by the report. Ocean acidity has increased by 30% since pre-industrial times and is projected to reach 170% by 2100. This change disproportionately affects coastal species, causing significant die-offs due to fluctuating acidity levels, and thus also presents a threat to aquaculture and fisheries.

Recognising the ocean's role in carbon sequestration, biodiversity and food security

Despite these alarming trends, the report also highlights some areas of hope.

The ocean acts as one of the planet's main carbon sinks, as marine forests, such as mangroves and seagrass plains, can absorb up to five times more carbon than terrestrial forests and are vital for biodiversity. However, the authors note, nearly 60% of countries do not include marine forest conservation in their climate plans.

The report also underlines the effectiveness of marine protected areas (MPAs) in protecting biodiversity, finding that higher regulation levels correlate with better ecosystem protection.

On aquaculture and fisheries, the report also highlights the crucial contribution of aquatic foods to global food security and nutrition in the context of climate change, stating that "aquatic foods are more efficient and sustainable than land-based animal food production systems and have a potential to be more impactful through technological innovation."

The report points out that the FAO's "Blue Transformation" roadmap aims at "growing aquaculture sustainably, especially in food deficit regions; ensuring all capture fisheries are placed under effective management [...] developing the value chains of aquatic foods, reducing loss and waste, adding value to products and facilitating their access to markets, especially for small producers."

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