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Ocean Undergoing Profound Climate Change Shifts
30 Sep
Summary
- Ocean absorbs 90% of excess heat from greenhouse gases.
- Sea levels are rising at an accelerated rate since 2012.
- Ocean acidity increased by 17% between 1985 and 2025.
Profound changes are underway in the world's oceans, driven by climate change, according to a major report by over 110 scientists. The ocean has absorbed approximately 90% of the excess heat trapped by greenhouse gas emissions. This absorption has led to significant warming, with an estimated 23 zettajoules of heat gained in 2025 alone.
The consequences include accelerated sea-level rise, which has increased from an average of 3.8mm annually between 1999 and 2025 to 4.2mm between 2012 and 2025. Record heatwaves, some lasting over 30 days, were observed in the Mediterranean and Black Seas in 2024. The ocean has also become about 17% more acidic since 1985 as it absorbs carbon dioxide.
Further impacts are evident in polar regions. Arctic sea surface temperatures have risen by approximately 4.2C over the past four decades, accompanied by a loss of sea ice extent averaging 4% per decade. In the Antarctic, sea ice loss is already affecting penguin populations and regional biodiversity. These ongoing transformations highlight the urgent need to address climate change's impact on marine environments.
