UNESCO State of the Ocean Report 2024

According to the UNESCO State of the Ocean Report 2024, ocean warming has accelerated, doubling the rate to 0.66 ± 0.10 W/m2 in the past two decades.

UNESCO State of the Ocean Report 2024 

• The UNESCO State of the Ocean Report 2024 offers insights on ocean-related scientific activities and analyses describing the current and future state of the ocean.
• The key message: It  is that observations and research on the state of oceans globally are falling short, and there is a lack of adequate and aggregated data to design solutions for multiple ocean crises and validate new technologies that aim to remove carbon dioxide from the atmosphere

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Key Highlights of the UNESCO State of the Ocean Report 2024

• Rising Ocean Temperature: From 1960 through 2023, the upper 2,000 metres (m) of oceans warmed at a rate of 0.32 ± 0.03 watt per square metre (W/m2).
• Increased Ocean Heat: About 90 per cent of the Earth’s energy imbalance (EEI) is absorbed by oceans, resulting in a cumulative increase in ocean heat content (OHC) in the upper 2,000 m of the water column.
  • OHC is the total amount of heat stored by the ocean, and EEI is the balance between incoming energy from the Sun and outgoing energy from the Earth.
• Impact of OHC: Increased OHC prevents ocean layers from mixing or deoxygenating, lowering the preformed oxygen content of near-surface high-latitude waters reaching the deeper layers of oceans. 
  • Although it is still unclear whether deoxygenation is accelerating in response to increased OHC, it can otherwise negatively impact the health of coastal and large marine ecosystems.
• Average increase in ocean acidification: The average global surface ocean pH has declined continuously by  0.017-0.027 pH units per decade in the open ocean since the late 1980s.
  • Inadequate Data: In 2024, only 638 stations recorded ocean pH levels, resulting in inadequate current coverage and a time series that is not long enough to determine trends and data gaps due to the lack of observations in all areas.
  • Other sources of Acidification: Coastal waters can turn acidic due to natural processes, such as freshwater influx, biological activity, temperature change and climate patterns like El Nino/Southern Oscillation (ENSO).
• Sea level Rise: It continued to rise in 2023, with the global mean sea level from 1993 to 2023 increasing at a rate of 3.4 +/-0.3 mm/yr.
  • Recommendation: The world needs to improve the space-based and in situ observing systems for monitoring sea level rise at global, regional, and coastal scales.
• Recent Trends in Marine Carbon Dioxide Removal (mCDR) Technologies: mCDR technologies involve techniques that capture carbon dioxide from the air and store it durably within the ocean ecosystem. 
  • Examples: It includes altering the chemical composition of seawater so that oceans absorb more carbon dioxide from the atmosphere or adding nutrients such as iron to encourage the growth of microscopic plankton that can sink to the seafloor and be stored for centuries or longer.
  • Challenges: The report noted widespread technical, environmental, political, legal, and regulatory challenges in the increased usage of mCDR technologies, with many unknowns about the unintended consequences of these new technologies 
• Coastal Blue Ecosystem Restoration: The report questions the effectiveness of restoring or expanding coastal blue carbon habitats such as mangrove forests, seagrass meadows, and tidal saltmarshes to increase carbon sequestration.

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