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Response of Ocean Acidification to Atmospheric Carbon Dioxide Removal Simulations

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Can Ocean Acidification Be Reversed?

A recently published research paper helps answer how oceans may respond to a removal of CO2 from the atmosphere. Here is a summary from the published paper. You can find the full paper online in the Journal of Environmental Sciences.

About The Study:

  • Study Focus: Investigates ocean acidification response to atmospheric CO2 removal using Earth system modeling.
  • Model: Uses the UVic Earth System Climate Model v2.10.
  • Simulations: Atmospheric CO2 rises 1% yearly to 4× pre-industrial levels, then decreases by 0.5%, 1%, or 2% yearly to pre-industrial levels.

Findings:

  • Surface Ocean Response: Quick response in annual mean surface ocean carbonate chemistry to atmospheric CO2 removal.
  • Deep Ocean Lag: Deep ocean carbonate chemistry lags behind atmospheric changes, still acidified when CO2 returns to pre-industrial levels.
  • Seasonal Cycles: Changes in the seasonal cycle of carbonate chemistry lag behind atmospheric CO2 decline.

Surface Chemistry Variables:

  • pH, hydrogen ion concentration, and aragonite saturation state adjust rapidly to CO2 removal.
  • Seasonal amplitudes of these variables lag behind, remaining altered when CO2 reaches pre-industrial levels.

Mechanisms:

  • DIC (Dissolved Inorganic Carbon) changes primarily drive changes in carbonate chemistry variables.
  • Seasonal changes are mostly due to changes in the ocean’s buffering capacity.

Deep Ocean Acidification:

  • Slower response than surface waters due to slow DIC penetration.
  • Even with pre-industrial CO2 levels, deep ocean remains acidified for decades/centuries.

Implications:

  • Marine ecosystems face a lagged recovery, with continuous acidification threatening marine life.
  • Amplified seasonal cycles can exacerbate impacts on marine organisms.

Acknowledgments: Supported by National Natural Science Foundation of China and Zhejiang Provincial Natural Science Foundation of China.

Considerations:

  • Didn’t consider the ballast effect or deep-sea carbonate sediments, which could buffer acidification.
  • Calls for more studies to understand carbonate chemistry’s impact on marine ecosystems under CO2 removal scenarios.

Declaration: No competing financial interests or personal relationships affecting the study.

21st-Century Ocean Acidification in Antarctic Protected Areas

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The research paper “Severe 21st-century ocean acidification in Antarctic Marine Protected Areas” by Cara Nissen et al., focuses on the future of ocean acidification (OA) in Antarctic Marine Protected Areas (MPAs) under different emission scenarios using a high-resolution ocean-sea ice-biogeochemistry model. The study highlights severe potential declines in pH and the consequences for marine biodiversity.

Map of Marine Protected Areas and Impacted Species

About This Map

This map of Antarctica featured in the study illustrates the locations of established and proposed Marine Protected Areas (MPAs) around the continent. It also highlights key marine species that may be negatively impacted by ocean acidification, with their positions around the map representing their typical habitats within these MPAs.

Key Takeaways:

  • Antarctic Vulnerability: Antarctic coastal waters, including several MPAs, are under threat from ocean acidification due to increased anthropogenic carbon uptake. These waters support exceptional biodiversity, making them critical to preserve.
  • Emission Scenarios and OA Projections: The study examines four emission scenarios, projecting significant pH declines by 2100, with the highest reductions under high-emission scenarios. This results in widespread aragonite undersaturation, affecting marine organisms that rely on calcium carbonate structures.
  • Biogeochemical Changes: Antarctic waters are highly sensitive to OA due to cold temperatures and upwelling of carbon-rich deep waters. The study highlights the enhanced vertical mixing of anthropogenic carbon on continental shelves, exacerbating local OA.
  • Impact on Marine Life: Various marine organisms, including primary producers and shell-forming species, are expected to face severe impacts from OA. The study notes potential declines in populations and shifts in community structures due to altered physiological processes and ecosystem dynamics.
  • Conservation Implications: The research supports the expansion of MPAs as a strategy to mitigate OA impacts and preserve marine biodiversity. It calls for strong emission-reduction efforts and enhanced management strategies to alleviate pressures on these ecosystems.
  • Modeling Approach: Utilizes a sophisticated modeling approach that integrates realistic ice-shelf geometry and high-resolution data, providing detailed projections that highlight the urgent need for climate action to protect Antarctic marine environments.