As global warming accelerates and society continues to emit greenhouse gases, the idea of investing in artificial carbon sequestration techniques is gaining traction. The long-term storage of carbon in plants, soils, geologic formations, and the ocean is known as carbon sequestration. It occurs both naturally and as a result of anthropogenic activities. The Intergovernmental Panel on Climate Change estimates that nations will need to remove between 100 billion and 1 trillion tonnes of carbon dioxide from the atmosphere this century to avoid the worst effects of climate change, far more than can be absorbed by simply planting more trees. In this article, we will discuss Carbon sequestration which will be helpful for UPSC exam preparation.

How is Carbon Sequestration Done?

• Carbon dioxide is naturally captured from the atmosphere via biological, chemical, and physical processes.
• These changes can be accelerated by changing land use and agricultural practices, such as converting crop and livestock grazing land to land for non-crop fast-growing plants.
• Artificial processes have been developed to produce similar effects, such as large-scale, artificial capture and sequestration of industrially produced carbon dioxide using subsurface saline aquifers, reservoirs, ocean water, aging oil fields, or other carbon sinks.

Sinks

• Carbon sequestration can be accomplished by pumping carbon into 'carbon sinks,' or areas that absorb carbon.
  • Natural sinks - oceans, forests, soil, etc.
  • Man-made sinks - depleted oil reserves, unmineable mines, etc.
• For decades, the oil and gas industries have used carbon capture to improve oil and gas recovery.
• We have only recently begun to consider capturing carbon for environmental reasons.
• Carbon capture and storage (CCS) consists of three major steps:
  • capturing and separating CO2 from other gases
  • transporting the captured CO2 to a location for storage, and
  • keeping CO2 out of the atmosphere by storing it underground or deep in the ocean.

Types of Sequestration

Ocean Sequestration

• Carbon is stored in the oceans via direct injection or fertilization.
• Large amounts of CO2 from the atmosphere is absorbed, released, and stored by the oceans.
• This can be accomplished in two ways: by increasing the productivity of ocean biological systems through iron fertilisation, and by injecting CO2 into the deep ocean.
• Iron dumping stimulates phytoplankton production, which leads to increased photosynthesis from these microorganisms, which aids in CO2 absorption.

Geologic Sequestration

• Natural pore spaces in geologic formations serve as long-term carbon dioxide storage reservoirs.
• CO2 can be stored in oil reservoirs, gas reservoirs, unmineable coal seams, saline formations, and organic-rich shale formations.
• Geologic sequestration is thought to have the most immediate application potential.

Terrestrial Sequestration

• Terrestrial carbon sequestration is the process by which CO2 from the atmosphere is absorbed by trees and plants via photosynthesis and stored as carbon in soils and biomass (tree trunks, branches, foliage, and roots).
• Soils and vegetation, which act as natural carbon sinks, store a large amount of carbon.
• Carbon uptake in these natural sinks can be increased by increasing carbon fixation through photosynthesis, slowing or reducing organic matter decomposition, and changing land-use practices.

Geologic Sequestration Trapping Mechanism

• Hydrodynamic Trapping: CO2 can be trapped as a gas by hydrodynamic trapping under low-permeability cap rock.
• Solubility Trapping: CO2 can be dissolved in a liquid, such as water or oil.
• Mineral Carbonation: CO2 can react with minerals, fluids, and organic matter in a geologic formation to form stable compounds/minerals, primarily calcium, iron, and magnesium carbonates.
• CO2 can be effectively stored in the earth's subsurface via hydrodynamic trapping and solubility trapping - a combination of the two is usually most effective.

Methods of Carbon Sequestration

Natural Carbon Sequestration

• It is the process by which nature has achieved a carbon dioxide balance in our atmosphere that is suitable for life. Plants and animals both expel carbon dioxide at night.
• Nature provided carbon sinks or sponges in the form of trees, oceans, the earth, and the animals themselves.
• All organic life on Earth is carbon-based, and when plants and animals die, much of the carbon returns to the ground, where it has little effect on global warming.

Artificial Carbon Sequestration

• Artificial carbon sequestration refers to a variety of processes that capture and bury carbon emissions at the point of production (e.g., factory chimneys).
• Ocean sequestration is one proposed method in which carbon dioxide is injected deep into the ocean, forming CO2 lakes.
• The CO2 will, in theory, stay deep due to the pressure and temperature of the surrounding water, gradually dissolving into it over time.
• Another example is geological sequestration, which involves pumping carbon dioxide into underground chambers such as old oil reservoirs, aquifers, and coal seams that cannot be mined.

Soil Carbon Sequestration

• Soil carbon refers to the solid carbon stored in the world's soils. This includes both organic soil matter and inorganic carbon in the form of carbonate minerals.
• Soil carbon is a carbon sink in the global carbon cycle, contributing to biogeochemistry, climate change mitigation, and the development of global climate models.
• Carbon dioxide concentrations in the atmosphere can be reduced by reducing emissions or by removing carbon dioxide from the atmosphere and storing it in terrestrial, oceanic, or freshwater aquatic ecosystems.
• Long-term conversion of grassland and forestland to cropland (and grazing lands) has resulted in historic losses of soil carbon worldwide, but there is significant potential for increasing soil carbon through soil restoration and widespread adoption of soil conservation practises.
• Land-use conversion and soil cultivation have historically been significant sources of greenhouse gases (GHGs) to the atmosphere. They are still estimated to be responsible for roughly one-third of GHG emissions.
• Improved agricultural practises, on the other hand, can help to mitigate climate change by lowering emissions from agriculture and other sources and storing carbon in plant biomass and soils.

Advantages and Disadvantages of Carbon Sequestration

Advantages

• Planting trees and managing their growth has been shown to reduce the number of harmful particulates in the air.
• Carbon sequestered is carbon that does not enter the atmosphere.
• Reduced carbon in the atmosphere reduces the greenhouse gas effect and mitigates the effects of climate change.

Disadvantages

• Carbon dioxide has the potential to be stored deep underground. Hydrostatic pressure acts at depth to keep it liquid.
• Faults in reservoir design, rock fissures, and tectonic processes may all act to release the gas stored in the reservoir into the ocean or atmosphere.
• According to estimates from climate change panels, using the technology would cost 1-5 cents per kilowatt-hour.
• If regulation required the use of CCS (Carbon Capture and Storage) technology, the financial costs of modern coal technology would nearly double.
• The cost of CCS technology varies depending on the type of capture technology used and the location in which it is implemented, but costs tend to rise with CCS capture implementation.

India and Carbon Sequestration

• National Programme on CO2 Storage Research is a programme run by the Department of Science and Technology.
• India is a member of the Accelerating CCS Technologies (ACT) initiative.
• ACT is a 16-country international initiative that aims to accelerate and mature CCUS technology through targeted innovation and research.
• Six Indian companies have agreed to a 'Industry Charter' for near-zero emissions by 2050, including carbon sequestration.

Conclusion

Carbon sequestration is a viable option for global leaders to achieve net zero emissions by 2050, as stated in the IPCC Report, in order to protect the planet from temperature rises of more than 2°C. A serious global collaboration and coordination is required for feasible technology development and affordable access for all, based on equity and climate justice principles.

FAQs

Question: What is carbon sequestration?

Question: Why is carbon sequestration important?

Question: What are the main types of carbon sequestration?

Question: How does soil carbon sequestration work?

Question: What role do forests play in carbon sequestration?

MCQs

1. Carbon sequestration is the process of:

A) Releasing more carbon dioxide into the atmosphere

B) Capturing and storing carbon dioxide to reduce its atmospheric concentration

C) Producing fossil fuels

D) Reducing oxygen levels in oceans

2. One natural method of carbon sequestration is through:

A) Fossil fuel combustion

B) Photosynthesis in plants

C) Chemical reactions in factories

D) Plastic waste disposal

3. Artificial carbon sequestration methods include:

A) Planting trees

B) Carbon capture and storage (CCS) technologies

C) Burning more coal

D) Building highways

4. Forests act as carbon sinks by:

A) Releasing excess carbon dioxide

B) Absorbing and storing carbon dioxide through photosynthesis

C) Converting carbon dioxide into methane

D) Reducing biodiversity

5. Which of the following practices enhances soil carbon sequestration?

A) Intensive tillage

B) Organic matter addition and cover cropping

C) Burning forests

D) Mining activities

GS Mains Questions and Model Answers

Q1: Explain the concept of carbon sequestration and its significance in combating climate change.

Answer: Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide to reduce its concentration and mitigate climate change. It occurs naturally through processes like photosynthesis, where plants absorb CO₂, and through artificial methods, such as carbon capture and storage (CCS) technologies that capture emissions from industrial sources. The significance of carbon sequestration lies in its ability to lower greenhouse gas concentrations, combat global warming, and balance the carbon cycle. By reducing atmospheric CO₂ levels, it helps mitigate the adverse effects of climate change, such as extreme weather events and rising sea levels. Forests, oceans, and soil play a crucial role in natural carbon sequestration, making their conservation essential for climate stability.

Q2: Discuss the role of forests and soil in natural carbon sequestration.

Answer: Forests and soil are vital components of natural carbon sequestration. Forests absorb carbon dioxide through photosynthesis and store it in trees, plants, and soil, acting as carbon sinks. They regulate the carbon cycle, reduce greenhouse gas concentrations, and play a key role in mitigating climate change. Similarly, soil captures and stores carbon through processes like organic matter accumulation, reduced tillage, and reforestation. Healthy soil ecosystems enhance carbon storage, improve soil fertility, and support biodiversity. Protecting and restoring forests and adopting sustainable land management practices are critical for maximizing their role in carbon sequestration and combating global warming.

Q3: Analyze the potential and limitations of artificial carbon sequestration methods in reducing greenhouse gas emissions.

Answer: Artificial carbon sequestration methods, such as carbon capture and storage (CCS) technologies, have significant potential to reduce greenhouse gas emissions by capturing CO₂ from industrial sources and storing it underground. These methods can mitigate emissions from power plants and other heavy industries, contributing to climate change mitigation efforts. However, they face limitations, including high costs, energy requirements for capturing and storing CO₂, and the need for secure long-term storage solutions to prevent leakage. Large-scale implementation and public acceptance also present challenges. Despite these limitations, CCS and other artificial methods can complement natural carbon sequestration efforts, providing a comprehensive approach to reducing atmospheric carbon dioxide levels.

Previous Year Questions on Carbon Sequestration

1. UPSC CSE 2020

Question: Evaluate the effectiveness of carbon sequestration as a tool for mitigating climate change.

Answer: Carbon sequestration is an effective tool for mitigating climate change by capturing and storing atmospheric carbon dioxide, thereby reducing greenhouse gas concentrations. Natural sequestration processes, such as photosynthesis in forests and carbon absorption in oceans, play a significant role in maintaining climate stability. Artificial methods, including carbon capture and storage (CCS), offer additional opportunities to reduce emissions from industrial sources. However, the effectiveness of these methods depends on factors such as scale, cost, technological advancements, and long-term storage security. Combining natural and artificial approaches, supported by policies and global cooperation, can enhance the overall impact of carbon sequestration in addressing climate change.

2. UPSC CSE 2019

Question: Discuss the challenges and opportunities associated with carbon sequestration in achieving global climate goals.

Answer: Carbon sequestration presents both challenges and opportunities in achieving global climate goals. On the positive side, it offers a means to capture and store carbon dioxide, mitigating the impact of greenhouse gas emissions on global warming. Natural sequestration through forests, soil, and oceans is cost-effective and sustainable, while artificial methods like carbon capture and storage (CCS) can target industrial emissions. Challenges include the high cost of CCS technologies, energy demands, potential risks of CO₂ leakage, and the need for extensive monitoring. Addressing these challenges requires investment in research, technological innovation, and supportive policies. By maximizing its potential, carbon sequestration can play a pivotal role in reducing emissions and achieving climate targets.