As the world faces the increasingly urgent threat of climate change, reducing atmospheric carbon dioxide (CO2) levels has become one of the most pressing challenges of our time. Governments, scientists, and environmental advocates are seeking innovative solutions that can help achieve global climate goals, such as those outlined in the Paris Agreement. These goals aim to limit global temperature rise to well below 2°C, with efforts to keep it under 1.5°C. Achieving these targets requires significant reductions in CO2 emissions and finding ways to capture and store excess carbon from the atmosphere.
One emerging solution is carbon subduction—a natural process that leverages the Earth’s tectonic movements to store carbon deep within the planet’s mantle. This method of carbon sequestration could play a key role in meeting global climate goals by providing a long-term and potentially permanent solution to atmospheric carbon storage. But what exactly is carbon subduction, and how can it help us in the fight against climate change? In this article, we’ll explore the science behind carbon subduction, its potential impact on global climate goals, and how it could be integrated into existing carbon management strategies.
Carbon subduction refers to the process of using tectonic subduction zones—areas where the Earth's tectonic plates collide and one plate is forced beneath the other—to sequester carbon deep within the Earth’s mantle. When tectonic plates converge, the descending plate (usually oceanic crust) carries with it sediments, carbonates, and organic matter that are rich in carbon. This material is subducted into the mantle, where the carbon can be stored for millions of years.
While carbon subduction occurs naturally as part of Earth’s geological processes, scientists are now exploring how we can enhance or leverage these natural processes to address the excess carbon in the atmosphere. By capturing carbon through various methods, such as direct air capture or industrial carbon capture, and delivering it to subduction zones, we could potentially sequester large amounts of CO2 in a way that is stable over the long term.
Meeting global climate goals requires significant reductions in CO2 emissions, as well as the removal of existing CO2 from the atmosphere. The Paris Agreement, for example, emphasizes the importance of achieving net-zero emissions by mid-century, which means that any remaining emissions must be balanced by an equal amount of carbon removal. This is where carbon subduction could play a critical role.
Carbon subduction offers the potential for permanent carbon sequestration. Unlike other methods of carbon capture and storage (CCS), which store CO2 in geological formations closer to the Earth’s surface, carbon subduction moves carbon much deeper—into the Earth’s mantle—where it is less likely to escape back into the atmosphere. This makes it an ideal solution for long-term storage, particularly when combined with existing efforts to reduce emissions and capture carbon.
Achieving net-zero emissions requires that the amount of carbon we emit is balanced by the amount we remove from the atmosphere. While reducing emissions from energy production, transportation, and industry is critical, it’s becoming increasingly clear that carbon removal technologies will also be necessary to meet these targets. This is particularly true for sectors that are difficult to decarbonize, such as heavy industry and aviation.
Carbon subduction provides a way to remove CO2 from the atmosphere and store it permanently. By capturing carbon from industrial sources or directly from the air, we can transport the captured carbon to subduction zones, where it is absorbed by the descending tectonic plates and transported deep into the Earth’s mantle. Over geological timescales, this carbon remains sequestered, reducing the overall amount of CO2 in the atmosphere.
This process could be a key component of achieving net-zero emissions by providing a reliable, long-term method of carbon removal. In conjunction with emissions reductions and other carbon capture technologies, carbon subduction could help bridge the gap between current emissions levels and the targets set by international climate agreements.
One of the key advantages of carbon subduction is the permanence of the carbon storage. Unlike surface-level CCS methods, which store carbon in underground reservoirs that could potentially leak or be disturbed, subduction zones transport carbon deep into the Earth’s mantle. Here, the carbon is subjected to extreme pressures and temperatures, making it far less likely to escape back into the atmosphere.
Another advantage is that carbon subduction works with natural geological processes. Subduction zones are already responsible for transporting carbon deep into the Earth’s interior as part of the natural carbon cycle. By enhancing or directing more carbon toward these zones, we can take advantage of the Earth’s natural mechanisms for long-term carbon storage. This also means that the infrastructure required for carbon subduction could be simpler and less invasive than other CCS technologies.
In addition to its geological benefits, carbon subduction could also be more scalable than some other forms of carbon sequestration. Many subduction zones are located in deep oceanic regions, meaning that vast areas of the Earth’s surface are already participating in this process. With proper technological advancements, carbon subduction could be implemented on a global scale.
Despite its potential, carbon subduction is still a developing field of research, and there are several challenges that must be addressed before it can become a widely adopted solution. One of the primary challenges is logistics. Subduction zones are often located deep beneath the ocean floor, making access difficult and costly. Transporting captured carbon to these remote regions will require significant infrastructure and coordination.
Additionally, more research is needed to understand the long-term behavior of carbon within subduction zones. While the process appears to offer permanent storage, it’s important to study how carbon behaves under the extreme conditions of the Earth’s mantle, and whether any of it might be released through volcanic activity or other geological processes.
There are also environmental and ethical considerations to take into account. While carbon subduction works with natural processes, any human intervention in geological systems needs to be approached with caution. Potential impacts on marine ecosystems, as well as the risk of triggering seismic activity, must be thoroughly evaluated before large-scale projects are undertaken.
Carbon subduction should not be viewed as a stand-alone solution, but rather as one component of a larger carbon management strategy. To meet global climate goals, it’s essential to combine carbon subduction with other methods of emissions reduction and carbon capture.
For example, renewable energy adoption is critical to reducing emissions from the power sector, while electric vehicles and public transportation can help reduce emissions from transportation. Industrial sectors, which are harder to decarbonize, may rely more heavily on carbon capture technologies. In this context, carbon subduction can provide a long-term solution for storing the carbon that is captured from these sectors, complementing other technologies such as geological carbon storage and bioenergy with carbon capture and storage (BECCS).
By integrating carbon subduction into national and international carbon management frameworks, we can ensure that it plays a role in helping achieve net-zero emissions by mid-century. Collaboration between governments, industries, and researchers will be essential to developing the technologies and infrastructure needed to make carbon subduction a viable option.
As the urgency to address climate change grows, innovative solutions like carbon subduction will become increasingly important. While it is still a developing field, the potential for long-term carbon sequestration in subduction zones offers hope for achieving the global climate goals outlined in agreements like the Paris Agreement.
Moving forward, it will be essential to continue researching the feasibility of carbon subduction, as well as its potential environmental impacts. Governments and international organizations should prioritize funding for research and development in this area, as well as support collaboration between countries that share subduction zones.
If successful, carbon subduction could become a cornerstone of global carbon management strategies, providing a reliable and permanent method of carbon removal that complements emissions reduction efforts. As we work toward a more sustainable future, leveraging natural processes like carbon subduction could help ensure that we meet our climate goals and protect the planet for future generations.