Clogging the Ocean Sink: Understanding the Positive Feedback Loop Driving to Climate Change

Writer: Y8 DaHyun (Anna) Ryu

In this article we will discuss the clogging of the ocean sink. The sea makes up 71% of the planet(Schmitt, 2018) and contributes significantly to climate through functioning as a reservoir, absorbing CO2 from the atmosphere. However, the efficiency of the ocean sink has declined in recent years. This has drawn my attention as I was writing an article related to marine life, and this topic is related to the sea. It was also something I had no knowledge about, and I was curious what it was. During this report, I hope to learn in more detail how the ocean sink functions and its cause for clogging.

The ocean sink absorbs about 30% of carbon emission in the atmosphere(NOAA, 2025), which is about 40000 pentagram of carbon located in water(Murphy and Measures, 2014) . The ocean absorbs CO2 in physical and biological means. Through physical pump, also known as thermohaline circulation, occurs more in high latitude, low temperature and saline water - which is the reason why ocean sink happens often in the arctic and atlantic - as it increases the density and sinks, then spread around the globe through global conveyor belt of marine circulation (Mejkut et al., 2014). Through a biological pump, the phytoplankton, which is a microscopic plant, performs photosynthesis on the surface of the water and absorbs carbon. When it dies, it sinks to the bottom of the ocean and the carbon it absorbs is buried and stored in the ground of the ocean(Pasaw and Carlson, 2012). 

The ocean which absorbs the most carbon is the Southern Ocean, as the Southern Ocean(located around Antarctica) does up to 50% of the total oceanic uptake of CO2 primarily due to thermohaline circulation(Majcut et al., 2014). 

However, these ocean sinks are being clogged, diminishing the capacity of the ocean to absorb carbon dioxide from the atmosphere. The clogging of the ocean is caused due to the rise of temperature. As the temperature of the ocean rises, the carbon sink through thermohaline circulation becomes harder as the water is less denser and it will not sink to the bottom like it used to, causing CO2 to be absorbed less or even release it. This leads to a never-ending positive feedback loop of temperature rise, release of CO2 which leads to more temperature rise.

Further investment should be made on solving the clogging of the ocean as it will advance climate change which affects everyone living on Earth. Potential solutions to this problem can be afforestation of the ocean by farming marine plants which can capture the CO2 in the atmosphere.

Citations

Eldevik, Tor, and Jan Even Ø. Nilsen. “The Arctic–Atlantic Thermohaline Circulation.” Journal of Climate, vol. 26, no. 21, 2013, pp. 8698–8705. JSTOR, http://www.jstor.org/stable/26192947. Accessed 4 June 2025.

Majkut, Joseph D., et al. “An Observing System Simulation for Southern Ocean Carbon Dioxide Uptake.” Philosophical Transactions: Mathematical, Physical and Engineering Sciences, vol. 372, no. 2019, 2014, pp. 1–17. JSTOR, http://www.jstor.org/stable/24503081. Accessed 4 June 2025.

Murphy, Jennifer L., and Christopher I. Measures. “Ocean Acidification: The Role of CO₂.” Oceanography, vol. 27, no. 1, 2014, pp. 238–246. JSTOR, http://www.jstor.org/stable/24862140. Accessed 4 June 2025.

National Oceanic and Atmospheric Administration. Ocean Acidification. https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification. Accessed 4 June 2025.

Schmitt, Raymond W. “The Ocean’s Role in Climate.” Oceanography, vol. 31, no. 2, 2018, pp. 32–40. JSTOR, https://www.jstor.org/stable/26542649. Accessed 4 June 2025.