Ocean's role as global carbon sink

Definition

The ocean's role as a global carbon sink refers to its ability to absorb and store carbon dioxide (CO2) from the atmosphere, significantly helping to regulate Earth's climate. This process is essential because it mitigates the greenhouse effect and helps maintain the planet's temperature by reducing atmospheric CO2 levels. Various oceanic processes, including biological uptake through photosynthesis and physical absorption of gases, contribute to the ocean's capacity to sequester carbon.

5 Must Know Facts For Your Next Test

1. The ocean absorbs about 30% of the carbon dioxide emitted by human activities, making it a vital player in mitigating climate change.
2. Phytoplankton, tiny marine plants, are responsible for a significant portion of the ocean's carbon uptake through photosynthesis.
3. Carbon can be stored in the ocean for long periods, ranging from decades to centuries, which is crucial for regulating climate over longer timescales.
4. The ability of oceans to act as carbon sinks is affected by temperature, salinity, and currents, all of which can change due to climate variability.
5. Increased levels of CO2 lead to ocean acidification, which can harm marine organisms like corals and shellfish that rely on calcium carbonate for their structure.

Review Questions

• How do biological processes in the ocean contribute to its role as a global carbon sink?
  • Biological processes such as photosynthesis carried out by phytoplankton play a significant role in the ocean's ability to act as a carbon sink. These tiny marine plants absorb carbon dioxide from the water during photosynthesis, converting it into organic matter. When phytoplankton die or are consumed by other organisms, some of this carbon is transferred to deeper waters or sediments, effectively sequestering it away from the atmosphere for extended periods.
• Evaluate the impact of increased atmospheric CO2 on the ocean's capacity as a carbon sink and its ecological consequences.
  • Increased atmospheric CO2 enhances the ocean's ability to absorb more carbon; however, this also leads to negative effects like ocean acidification. The extra CO2 lowers ocean pH levels, adversely affecting marine organisms that rely on calcium carbonate structures, such as corals and shellfish. This ecological shift can disrupt food webs and biodiversity in marine environments, ultimately compromising the long-term effectiveness of oceans as carbon sinks.
• Synthesize information on how the interplay between climate change and ocean chemistry affects global carbon cycling.
  • The interplay between climate change and ocean chemistry significantly influences global carbon cycling. As temperatures rise due to climate change, the solubility of CO2 in seawater decreases, which may reduce the ocean's ability to absorb this greenhouse gas. Additionally, alterations in ocean circulation patterns can affect nutrient availability for phytoplankton, potentially diminishing biological carbon uptake. These changes highlight a complex feedback loop where climate change impacts the ocean's role as a carbon sink while simultaneously being influenced by alterations in ocean chemistry.

Related terms

Carbon Sequestration:

The process of capturing and storing atmospheric carbon dioxide in various sinks, including forests, soils, and oceans.

Photosynthesis:

The process by which marine plants, such as phytoplankton, convert sunlight into energy while absorbing CO2, playing a crucial role in the ocean's carbon cycling.

Ocean Acidification: The decrease in pH levels of the ocean caused by increased absorption of CO2, leading to detrimental effects on marine life and ecosystems.