The pressing need to reduce carbon dioxide (CO₂) emissions in order to address the global climate crisis has prompted a shift in focus towards the development of technologies capable of actively removing CO₂ from the atmosphere. In line with this, the latest report from the Intergovernmental Panel on Climate Change has stressed the importance of CO₂ removal in limiting global warming to below 1.5°C. Consequently, ocean-based CO₂ removal technologies have attracted significant attention and government funding in countries such as the United States, United Kingdom, and Australia.
The effectiveness of these technologies, however, is closely linked to the behaviour of the ocean’s smallest inhabitants – plankton. Phytoplankton, microscopic ocean plants, utilize sunlight and CO₂ for photosynthesis, while zooplankton, tiny animals, consume phytoplankton. The relationship between these organisms is pivotal to the ocean’s carbon cycle, influencing the transfer of carbon from the atmosphere to the ocean, a process known as the “biological pump”.
Recent research has unveiled a crucial finding regarding zooplankton appetites and their impact on the biological pump. A study conducted by a team of researchers utilized advanced computer modelling and satellite data to evaluate the seasonal cycles of phytoplankton populations and zooplankton appetites in various oceanic locations. Their findings revealed that the diversity in zooplankton appetites significantly diminishes the strength of the biological pump, subsequently impacting the amount of carbon stored in the ocean.
Furthermore, the study highlights the potential influence of ocean-based CO₂ removal technologies on phytoplankton communities, which in turn could affect the behaviour of zooplankton and subsequently, the efficiency of the biological pump. Technologies such as ocean alkalinity enhancement and ocean iron fertilisation could potentially alter the composition and abundance of phytoplankton, further impacting the carbon storage capacity of the ocean.
Moving forward, it is imperative for the oceanographic community to establish necessary standards for assessing the impact of CO₂ removal technologies on marine ecosystems. This includes focusing on accurately monitoring and predicting the effects of these technologies on zooplankton dynamics, in order to ensure alignment with the required standards for accrediting CO₂ removal companies.
In conclusion, the findings of the research demonstrate the critical role of marine ecosystems, particularly plankton, in influencing the efficiency of CO₂ removal technologies. Addressing the uncertainties and challenges associated with the impact of these technologies on marine life is paramount in establishing a reliable and ethically imperative CO₂ removal industry.
Samantha Johnson, PhD in Oceanography
– University of Southampton