Ahead of UN World Oceans Day, a new UN report reveals that the rate of ocean warming has doubled in the past 20 years. Unlike the fluctuating atmospheric temperatures, the ocean has been steadily heating up, with 2023 recording one of the highest increases since the 1950s.
The State of the Ocean Report indicates that the ocean is now warming at twice the rate it was two decades ago. Despite the Paris Agreement’s goal to limit global warming to below 2°C above pre-industrial levels, ocean temperatures have already risen by an average of 1.45°C, with significant hotspots in the Mediterranean, Tropical Atlantic Ocean, and Southern Oceans exceeding 2°C.
UN Secretary-General Antonio Guterres emphasized the vital role of the ocean in sustaining life on Earth and pointed out that the current problems are largely man-made. “Climate change is triggering rising seas and threatening the very existence of small island developing states and coastal populations,” he stated.
Antonio Guterres also highlighted that ocean acidification is devastating coral reefs, while record sea temperatures are leading to extreme weather events. Overfishing and other human activities are further degrading marine ecosystems.
One significant consequence of ocean warming is the global rise in sea levels. The ocean absorbs 90 percent of the excess heat from the atmosphere, causing water to expand. This thermal expansion now accounts for 40 percent of global sea-level rise, which has doubled over the past 30 years, totaling a 9 cm increase.
Additionally, coastal species are suffering from declining oxygen levels. Since the 1960s, the ocean has lost 2 percent of its oxygen due to warming temperatures and pollutants, including wastewater and agricultural runoff. This has created roughly 500 “dead zones” where almost no marine life survives due to low oxygen levels.
Rising acidity is another major concern. The ocean absorbs 25-30 percent of fossil fuel emissions, leading to increased CO2 levels that alter the ocean’s chemical composition. Ocean acidity has risen by 30 percent since pre-industrial times and is projected to increase by 170 percent by 2100. Coastal waters are experiencing dramatic fluctuations in acidity, causing mass die-offs among fragile young marine life.
Despite these challenges, there are signs of hope. Marine forests, such as mangroves, seagrass plains, and tidal marshes, can absorb up to five times more carbon than terrestrial forests and are crucial for biodiversity. However, nearly 60 percent of countries do not include marine forest restoration and conservation in their Nationally Determined Contribution plans.
Marine Protected Areas (MPAs) also play a critical role in preserving biodiversity, sheltering 72 percent of the 1,500 endangered marine species on the IUCN Red List. The report shows that MPAs with higher levels of regulation are more effective at protecting local ecosystems.
The findings underscore the urgent need for global action to protect and restore marine environments, crucial for combating climate change and preserving biodiversity.