Exploring the Potential of Small Ocean Creatures in the Fight Against Climate Change

The global fight against climate change continues to evolve as researchers and scientists explore innovative ways to reduce carbon emissions and mitigate the environmental impacts of greenhouse gases. One promising area of study involves the ocean's ability to sequester carbon, with small ocean creatures such as zooplankton playing a crucial role. According to researchers at Dartmouth College, these tiny organisms, along with the addition of clay dust on the ocean's surface, could offer a natural and effective method to help bury carbon in the depths of the ocean. This process, known as the "biological pump," is already at work, and enhancing it could be key to addressing the growing carbon emissions problem.

The Genesis of the Idea

In 2016, Dartmouth professor Mukul Sharma began to contemplate the seemingly insurmountable task of rapidly reducing carbon emissions in line with global climate goals. The year after the Paris Agreement was signed—an international treaty aimed at limiting global temperature rise to below 2°C—Sharma began studying the Marcellus Shale, a significant source of fracked gas in the United States. His research led him to recognize an intriguing connection between carbon and clay, which had been in a symbiotic relationship for hundreds of millions of years after being deposited underwater.

As he delved deeper into the geological processes that formed fossil fuel reservoirs, Sharma started to entertain the possibility that these ancient processes could offer valuable insights into modern-day carbon removal strategies. One such idea involved sprinkling clay dust on the surface of the ocean. Sharma believed that this approach could potentially enhance the ocean's natural ability to sequester carbon by aiding the biological pump mechanism.

The Ocean's Natural Carbon Sequestration System: The Biological Pump

The ocean is already playing a significant role in mitigating climate change. In fact, it has absorbed approximately 90% of the excess heat generated by human activities through greenhouse gas emissions. Additionally, the ocean is responsible for sequestering around a quarter of all carbon dioxide emissions. One of the primary methods through which the ocean captures carbon is called the biological pump. This natural process involves tiny ocean plants called phytoplankton, which act in much the same way as trees by taking in carbon dioxide (CO2) during photosynthesis. However, the oceanic biological pump works on a different scale, with phytoplankton storing the absorbed carbon at great depths when they die.

Challenges with the Biological Pump

While the biological pump is a crucial part of the ocean's carbon sequestration process, it is not without its challenges. Phytoplankton, unlike trees, have a relatively short lifespan—typically around 20 days. Upon their death, the phytoplankton are consumed by bacteria in the ocean, which results in the release of much of the carbon they had absorbed. This cycle, known as remineralization, means that the carbon is often returned to the atmosphere rather than being securely stored in the ocean for the long term. Thus, the biological pump's effectiveness is limited by the rapid decomposition of phytoplankton and the associated release of carbon back into the atmosphere.

Clay Dust and Its Role in Enhancing Carbon Sequestration

Sharma's breakthrough came when he began experimenting with the addition of clay to ocean water. He discovered that clay particles have a unique ability to absorb carbon, and they can interact with organic carbon produced by phytoplankton. In laboratory experiments and studies using water and plankton samples from the Gulf of Maine, Sharma's team found that when bacteria were present, they attached to the clay particles along with the carbon. The bacteria produced a sticky, gooey substance that entangled the phytoplankton, creating clumps that were heavier and more likely to sink.

This discovery led Sharma to hypothesize that by adding clay dust to the surface of the ocean, it might be possible to enhance the biological pump's effectiveness. As the clay particles sink through the water, they carry the trapped organic carbon along with them. The sticky blobs of organic material, enriched with clay, fall to the ocean floor, where they become a food source for zooplankton—tiny animals that live in the deep ocean but rise to the surface at night to feed. The zooplankton consume the organic matter, and in the process, their feces, which are heavier due to the presence of clay, sink rapidly to the ocean's depths, carrying the sequestered carbon with them.

The Role of Zooplankton in Carbon Sequestration

Zooplankton play an essential role in the ocean's carbon cycle. By consuming organic material, including the carbon-rich particles produced by phytoplankton, zooplankton help transport carbon to deeper layers of the ocean. Their fecal matter, laden with carbon, becomes part of the ocean’s sediment, where it can remain for centuries. This process of carbon burial is crucial for mitigating climate change, as it effectively removes CO2 from the atmosphere for long periods of time. In this way, the zooplankton act as key players in the biological pump, helping to secure carbon deep within the ocean's interior.

Possible Risks and Uncertainties

While the concept of enhancing the biological pump with clay dust is promising, Sharma acknowledges that more research is needed to fully understand the potential risks and consequences of such an intervention. One possible side effect of adding clay to the ocean is that it could cause certain areas to lose oxygen, a condition known as anoxia. This could lead to the creation of "dead zones" in the ocean, where marine life cannot survive due to a lack of oxygen. While this risk is concerning, Sharma believes that the process is ultimately guided by natural processes that have been at work for millions of years, such as the geological processes that formed oil and gas deposits.

Examples of Natural Processes and Modern Interventions

The idea of using dust to enhance carbon sequestration is not entirely new. In fact, natural dust storms, such as those from the Sahara Desert, already contribute to carbon burial in the ocean. Research has shown that dust from the desert blows across the Atlantic Ocean, and this dust can enhance carbon sequestration by promoting the growth of phytoplankton, which absorb CO2 during photosynthesis. Similarly, researchers are exploring ways to artificially introduce dust and other minerals into the ocean to promote carbon capture. This method, known as ocean fertilization, has gained attention as a potential way to accelerate the natural carbon sequestration process.

The Future of Ocean-Based Carbon Sequestration

Despite the challenges, Sharma and his team remain optimistic about the potential of enhancing the ocean's natural processes to help address climate change. With human activities contributing nearly 40 billion tons of carbon dioxide to the atmosphere each year, finding effective and scalable ways to sequester this carbon is critical to avoiding catastrophic climate impacts. Sharma’s team is preparing to conduct a field experiment off the coast of Southern California, where they will test the effectiveness of adding clay dust to the ocean in a controlled, real-world setting.

Sharma likens the process to space exploration, where progress is made in small, incremental steps. "One has to always move with baby steps here," he says. "It’s like going to the moon. You want to make sure that you get there and the rocket doesn’t explode halfway through and you can come back." This cautious, step-by-step approach is essential when dealing with such a complex and potentially risky intervention in the natural environment.

Conclusion: A Promising Yet Cautious Path Forward

The idea of using small ocean creatures, like zooplankton, in combination with clay dust to enhance carbon sequestration offers a promising avenue for tackling climate change. While there are still many unknowns and potential risks, the concept follows nature's example, where carbon has been stored in the earth's depths for millions of years. By learning from these natural processes and exploring modern methods of intervention, researchers may uncover viable solutions to the climate crisis. However, careful experimentation, long-term studies, and monitoring will be necessary to ensure that the benefits of such interventions outweigh the potential risks.