UNESCO reports that the rate of ocean warming has nearly doubled over the past 20 years.
FRANCE PARIS : UNESCO
A new report from UNESCO reveals alarming data regarding ocean changes, including a doubling in the rate of ocean warming over the past 20 years and a doubling in the rate of sea level rise over the past 30 years. This report, which includes contributions from over 100 scientists from 30 countries worldwide and is supported by Iceland, presents evidence-based insights into escalating issues such as ocean warming, sea level rise, pollution, acidification, oxygen depletion, blue carbon, and biodiversity loss.
The continuous rise in ocean temperatures serves as a warning of the ongoing climate crisis. According to the report, ocean temperatures have increased by an average of 1.45°C since the pre-industrial era, with some areas showing hotspots of over 2°C, particularly in the Mediterranean Sea and tropical Atlantic. This warming has contributed to a global sea level rise of 9 cm over the past 30 years, which accounts for 40% of the overall rise, as the oceans absorb 90% of the excess heat from the atmosphere.
The effects of rising temperatures extend beyond sea level changes, as oxygen levels in the oceans are also decreasing. The report indicates that since the 1960s, the ocean has lost 2% of its oxygen content, particularly in coastal regions, resulting in over 500 identified “dead zones” where marine life struggles to survive due to oxygen depletion.
Another major concern is ocean acidification. As the oceans absorb 25-30% of carbon dioxide (CO2) emissions from fossil fuels, their chemical composition changes. Ocean acidity has increased by 30% since the pre-industrial era and is projected to rise by 170% by 2100. This acidification disproportionately affects coastal species, as these waters experience extreme fluctuations in acidity, causing young and fragile marine species to die off in large numbers.
Despite these challenges, there is hope in the form of blue carbon ecosystems and marine protected areas (MPAs). Mangroves, seagrass beds, and salt marshes can absorb five times more carbon than terrestrial forests. In addition to being vital habitats for biodiversity, these ecosystems serve as critical defenses against global warming. However, the UNESCO report highlights that nearly 60% of countries have yet to incorporate marine ecosystem restoration into their Nationally Determined Contributions (NDCs) to reduce carbon emissions (UNESCO, 2024).
As a global leader in ocean science, UNESCO has initiated over 500 projects since the beginning of the United Nations Decade of Ocean Science for Sustainable Development, mobilizing over $1 billion in funding to improve ocean protection and understanding. Through its more than 230 marine biosphere reserves and over 50 marine World Heritage sites, UNESCO remains the guardian of some of the planet’s most critical and diverse ocean ecosystems.
