UNESCO’s State of Ocean Report highlights key knowledge gaps in research & data on spiking oceanic warming

UNESCO’s State of Ocean Report highlights key knowledge gaps in research & data on spiking oceanic warming

Sub: Geography

Sec: Oceanography

Context:

• The UNESCO State of Ocean Report 2024 highlights critical issues concerning the ocean’s role in climate regulation and the insufficient understanding and data needed to address multiple ocean crises and validate new carbon dioxide removal technologies.

Key points from the report include:

1. Inadequate Data and Research:
   • The report emphasizes a lack of adequate and aggregated data necessary for comprehensive ocean observations and research.
   • There is a pressing need for regular data to monitor ocean warming and its impacts, supporting the challenge for healthy and resilient oceans.
2. Ocean Warming:
   • From 1960 to 2023, the upper 2,000 meters of oceans warmed at a rate of 32 ± 0.03 W/m², which has accelerated to 0.66 ± 0.10 W/m² in the past two decades.
   • This warming trend is expected to continue, causing irreversible changes over centennial to millennial timescales.
3. Energy Imbalance and Heat Content:
   • Oceans absorb about 90% of the Earth’s energy imbalance (EEI), leading to increased ocean heat content (OHC) in the upper 2,000 meters.
   • Increased OHC inhibits ocean layer mixing, causing deoxygenation, which negatively impacts marine ecosystems and coastal communities reliant on oceans.
4. Ocean Acidification:
   • The report identifies a mean global increase in ocean acidification across all ocean basins.
   • There has been a continuous decline in open ocean pH levels, with a drop of 017-0.027 pH units per decade since the late 1980s.
   • Current monitoring is limited, with only 638 stations recording ocean pH, and more extensive, long-term data sets are needed.
5. Sea Level Rise:
   • From 1993 to 2023, the global mean sea level rose at a rate of 4 ± 0.3 mm/year.
   • Enhanced monitoring systems are needed to track sea level rise at various scales.
6. Marine Carbon Dioxide Removal (mCDR):
   • The report notes a growing interest in mCDR technologies since 2020, driven by scientific research, start-up initiatives, and significant funding from the U.S. and EU.
   • mCDR techniques include altering seawater chemistry and adding nutrients to promote plankton growth, but they pose various challenges and uncertainties regarding their efficacy and potential unintended consequences.
7. Coastal Blue Carbon Habitats:
   • There is increased interest in restoring coastal blue carbon habitats like mangroves, seagrasses, and tidal marshes to enhance carbon sequestration.
   • The effectiveness of these habitats in sequestering carbon remains uncertain.

Important terms:

• Carbon sequestration- the process of capturing carbon dioxide from the atmosphere, measured as a rate of carbon uptake per year.
• Carbon storage- the long-term confinement of carbon in plant materials or sediment, measured as the total weight of carbon stored.

Carbon Dioxide Removal (CDR):

• It is using technologies, practices, and approaches to remove carbon dioxide from our atmosphere through deliberate and intentional human actions.
• This includes traditional methods like afforestation, as well as more sophisticated technologies like direct air carbon capture and storage (DACCS).

Different CDR methods:

• Biochar:
  • It is the substance produced by burning organic waste from agricultural lands and forests in a controlled process called pyrolysis.
  • Although it resembles common charcoal in appearance, the production of biochar reduces contamination and is a method to safely store carbon.
  • Pyrolysis involves the burning of wood chips, leaves, dead plants, etc. with very little oxygen, and the process releases a significantly small quantity of fumes.
  • Biochar is a stable form of carbon that cannot easily escape into the atmosphere.
• Bioenergy with carbon capture and storage (BECCS)
  • It involves bioenergy production often through combustion to generate electricity or heat.
  • The resulting CO2 emissions from this combustion are captured and stored underground, preventing them from contributing to the greenhouse effect.
  • It sequesters photosynthetically fixed carbon as post-combustion CO2.
• Direct air carbon capture and storage (DACCS)
  • It extracts CO2 directly from the atmosphere at any location.
  • This captured CO2 is then permanently stored in deep geological formations or used for other applications.
  • It uses electricity to remove CO2 from the air.
• Enhanced rock weathering
  • It involves pulverising silicate rocks to bypass the conventionally slow weathering action.
  • The resultant product, usually a powder, has a higher reactive surface area, which is then spread on agricultural lands for further chemical reactions.
• Ocean alkalinity enhancement
  • It involves adding alkaline substances to seawater to accelerate this natural sink.

Source: DTE