Oceans and CO2 absorption

Extreme weather events are becoming more common worldwide, reminding us of the climate crisis. Earth’s temperature hasn’t been this high in over 100,000 years, and the current levels of carbon dioxide pollution, along with projected emissions, continue to negatively impact the environment. The situation will only worsen until we reduce emissions to zero. However, simply reducing emissions is no longer sufficient. Climate models now indicate that actions aimed at removing carbon dioxide from the atmosphere and storing it will be key to mitigating the effects of climate change.

Carbon dioxide removal involves extracting excess carbon from the atmosphere using various methods—from reforestation and soil carbon sequestration to industrial processes that capture carbon directly from the air and store it underground. Lesser-known but potentially significant are methods that utilize the natural ability of oceans to absorb and store carbon.

The deep oceans already contain more carbon than any other part of Earth’s biosphere and have the potential to absorb even more. Due to the vast size of the oceans, if methods of removing carbon dioxide from sea waters prove feasible and safe, they can be scaled in a way that significantly impacts the climate. Considering the need to remove carbon in the latter half of this century and the potential for such activities in the oceans, it is crucial to continue intensive research and public dialogue on the effectiveness of marine CDR (Carbon Dioxide Removal) methods, especially regarding whether they can be implemented beneficially without harming people and ecosystems.

Among the approaches to marine CDR, ocean iron fertilization shows great potential. This method involves adding iron to iron-deficient ocean regions, which stimulates the growth of phytoplankton, microscopic marine plants that are crucial for carbon sequestration. As they grow, phytoplankton absorb carbon dioxide from the atmosphere through photosynthesis. When phytoplankton die or are consumed by other organisms, some of the absorbed carbon sinks to the ocean floor, effectively removing it from the atmosphere for centuries or more.

Ocean iron fertilization has a complex history, dating back nearly 40 years as a potential climate change mitigation technique. Field experiments conducted in the 1990s and 2000s confirmed that iron limitation was a reality in extensive areas of the global ocean, and iron additions stimulated plankton growth. However, many of these trials did not fully address how effectively phytoplankton growth from iron additions could lead to long-term atmospheric carbon dioxide storage in ocean depths, which is key to assessing iron fertilization as a sustainable method of carbon removal. Further research was halted due to early attempts at commercialization.

Currently, scientists and researchers are determined to explore the remaining questions regarding ocean iron fertilization (OIF) and intend to do so rigorously and inclusively, engaging communities and stakeholders with interests in marine spaces. Continuing research may find that OIF can be conducted safely and ecologically, or that it requires support from the communities where it might be implemented.

Given the growing urgency of solutions related to carbon dioxide removal, the scientific community has recently decided to resume discussions on iron fertilization of the oceans to address all remaining questions. In this context, it is extremely important to conduct research in a rigorous and transparent manner, designed in collaboration with indigenous and coastal communities.

In summary, in the face of climate anomalies, the exploration of ocean iron fertilization requires careful consideration with respect for environmental integrity and ethical responsibility. Field trials are essential to assess different ways of using OIF for carbon dioxide removal while protecting against unintended consequences that could disrupt marine ecosystems. Through thorough research, monitoring, and regulations, we can mitigate potential risks associated with these trials and contribute to a more sustainable and climatically stable future.

About the author

Picture of Grzegorz Bubak

Grzegorz Bubak

My fascination with marine aquariums began over two decades ago when I stumbled upon an article about this topic in a magazine. Since then, the underwater world has become my obsession and passion, shaping my everyday life. I started my adventure with marine aquariums with soft corals, which were my first step into this fascinating world. Over time, captivated by the diversity and beauty of SPS corals, I decided to focus on their cultivation, which continues to fill me with constant wonder.

Thanks to my experience and passion for marine aquariums, I am ready to share my knowledge and expertise with other enthusiasts in this field. I am happy to be part of the Reef Pedia community, which serves as an invaluable source of information for all marine aquarium lovers.