Shankar IAS Summary Mitigation Strategies - Famous Books for UPSC Exam

Table of Contents
1. Carbon Capture and Storage (CCS): overview
2. Storage options
3. Geologic sequestration: trapping mechanisms
4. Carbon sinks: green and blue carbon
5. Importance of blue carbon ecosystems
6. Carbon credits and carbon markets
7. Carbon offsetting
8. Carbon tax
9. Geoengineering: large-scale intervention concepts
10. Commercial and practical uses of captured CO2
11. Quality and permanence considerations for sequestration and offsets
12. Policy, markets and international context
13. Practical notes and examples
14. Final summary
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Our planet is warming because of elevated concentrations of carbon dioxide (CO2) and other greenhouse gases in the atmosphere, largely from burning fossil fuels and land-use change. Carbon sequestration refers to processes and technologies that remove CO2 from the atmosphere or prevent it from reaching it, and then keep that carbon isolated for long periods. These approaches include natural biological sinks, engineered capture and storage systems, market instruments and policy measures, and speculative large-scale interventions often called geoengineering.

Carbon Capture and Storage (CCS): overview

Carbon Capture and Storage (CCS) is a set of technologies and processes that capture CO2 from point sources or directly from the air, transport the captured CO2 and store it so it does not enter or return to the atmosphere. CCS is used both to reduce industrial emissions and, historically, in enhanced oil recovery operations.

Why CCS is used

• Reduce atmospheric emissions: CCS prevents carbon dioxide generated by fossil fuel combustion or industrial processes from reaching the atmosphere, helping mitigate global warming.
• Bridge to low-carbon energy: CCS allows continued use of some existing industrial infrastructure while technologies and systems transition towards low-carbon alternatives.
• Industrial applications: Some industries (cement, steel, chemicals) emit process CO2 that is difficult to avoid without capture technologies.

Three principal steps of CCS

1. Capture (Trapping and separating CO2): CO2 is separated from flue gases, process streams or directly from ambient air using chemical solvents, physical absorption, membranes, adsorption or other separation technologies.
2. Transport: Captured CO2 is moved, typically by pipeline or by ship, to a storage or utilisation site.
3. Storage (Sequestering CO2 away from the atmosphere): CO2 is placed in secure locations where it will remain isolated, such as deep geological formations, depleted hydrocarbon reservoirs, saline aquifers, or - in some proposals - in the deep ocean. Stored CO2 may also be used industrially, provided the use does not lead to immediate re-release to the atmosphere.

Storage options

Storage options can be broadly grouped into natural sinks and engineered/artificial sinks. Each option has benefits, risks and timescales of permanence.

Natural sinks

• Terrestrial (land) sinks: Vegetation and soils capture carbon through photosynthesis. Forests, grasslands and well-managed agricultural soils act as long-term biological carbon stores. Actions such as afforestation, reforestation and improved land management increase biological sequestration.
• Ocean (blue) sinks: Oceans absorb a large share of anthropogenic CO2 through physical dissolution and biological processes; coastal ecosystems such as mangroves, tidal marshes and seagrasses (collectively called blue carbon ecosystems) store carbon efficiently in biomass and sediments.

Engineered / artificial sinks

• Geologic (underground) storage: Injecting CO2 into deep rock formations, depleted oil and gas fields, or deep saline aquifers where it can be trapped for centuries to millennia.
• Industrial utilisation with long-term storage: Converting CO2 into stable materials (for example, mineral carbonates used in construction) or using CO2 in processes that lock carbon for long periods.
• Ocean storage (engineered): Proposed methods include direct injection into deep ocean waters or stimulating biological uptake. Such methods raise legal, ecological and permanence concerns and require international governance and careful scientific evaluation.

Geologic sequestration: trapping mechanisms

When CO2 is stored in subsurface geologic formations, several physical and chemical mechanisms contribute to its containment. These are complementary and often act sequentially over different timescales.

1. Hydrodynamic trapping (structural and stratigraphic trapping): CO2 in a buoyant gaseous or supercritical state accumulates beneath an impermeable cap rock or seal. The cap rock restricts upward migration, analogous to how oil and gas are trapped in reservoirs.
2. Solubility trapping: CO2 dissolves into the formation water or oil, reducing the freephase CO2 volume and increasing density; dissolved CO2 is less likely to migrate rapidly to the surface.
3. Mineral carbonation (geochemical trapping): Dissolved CO2 reacts with host rock minerals and formation fluids to form stable carbonate minerals (for example, calcium, magnesium or iron carbonates), permanently locking carbon into solid form.
4. Residual trapping: CO2 becomes immobilised in the pore spaces of the rock as disconnected droplets or bubbles held by capillary forces; this is especially important in the early to mid-term containment.
5. Combined trapping: Robust storage designs rely on a combination of structural, residual, solubility and chemical trapping mechanisms to achieve long-term safety and permanence.

Carbon sinks: green and blue carbon

1. Green carbon: Carbon stored in terrestrial vegetation and soils through photosynthesis. Forests are major green carbon reservoirs; mature forests store carbon over decades to centuries. Land-use practices such as afforestation, reforestation and improved ecosystem management increase green carbon stocks.
2. Blue carbon: Carbon captured and stored in coastal and marine ecosystems-principally mangroves, tidal marshes and seagrasses. These systems sequester carbon rapidly and store large quantities in sediments, often for centuries. Coastal blue carbon ecosystems are present on most continents and can store more carbon per unit area than many terrestrial forests.

Importance of blue carbon ecosystems

• Climate mitigation: Blue carbon ecosystems remove CO2 from the atmosphere and sequester it in biomass and sediments.
• Co-benefits: They provide coastal protection, fisheries habitat, biodiversity conservation and livelihoods for local communities.
• Vulnerability: These ecosystems are being lost rapidly. When degraded or converted, they release stored carbon back to the atmosphere and reduce future sequestration potential.

Blue Carbon Initiative and international cooperation

The Blue Carbon Initiative is a global programme that coordinates efforts to protect and restore coastal blue carbon ecosystems. Major organisations collaborating under this initiative include Conservation International (CI), the International Union for Conservation of Nature (IUCN) and the Intergovernmental Oceanographic Commission (IOC) of UNESCO, working with governments, research institutions, nongovernmental organisations and local communities to:

1. Develop management plans, finance mechanisms and policy instruments for coastal blue carbon conservation and restoration.
2. Engage local, national and international governments to align policy and funding with conservation goals.
3. Improve carbon accounting methods for coastal ecosystems to measure and report carbon stocks and fluxes accurately.
4. Design incentive mechanisms, including payments for ecosystem services and carbon project finance, to support conservation.
5. Implement demonstration projects worldwide to show practical approaches for protecting and enhancing blue carbon.
6. Support scientific research to improve understanding of coastal carbon dynamics and the climate mitigation potential of these ecosystems.

Carbon credits and carbon markets

Carbon credits are tradable certificates representing the right to emit a specified quantity of greenhouse gases, commonly one metric tonne of CO2 equivalent (CO2e). Credits are created when a project or entity reduces, avoids or removes emissions compared to a baseline.

1. How credits are generated: A project that reduces one tonne of CO2e compared with business-as-usual can generate one carbon credit if reductions are measured, verified and certified.
2. Role in compliance and voluntary markets: Under international agreements (for example, mechanisms developed after the Kyoto Protocol) and national systems, credits can be used to meet regulatory obligations. Voluntary markets allow organisations and individuals to purchase credits to offset emissions.
3. Market characteristics: Carbon trading has become a sizeable market. Market figures vary with time; as an indicative snapshot, global trading has been valued in the billions of US dollars, with major buyers in Europe and large volumes supplied by countries with low-cost mitigation opportunities. Exchanges such as India's Multi Commodity Exchange (MCX) have listed carbon as a tradable commodity in Asia.
4. Geographical dynamics: Developing countries with mitigation projects (for example, parts of India and China) may supply credits, while developed regions may be net buyers. Historical analyses have shown significant market shares for nations such as China in traded volumes.

Carbon offsetting

Carbon offsets are instruments purchased to compensate for emissions by funding equivalent emission reductions or removals elsewhere. Offsets are expressed in metric tonnes of CO2e.

1. How offsets work: An entity that still emits CO2 can buy offsets from projects that reduce or remove emissions (for example, renewable energy projects, household energy improvements, reforestation), thereby claiming a net reduction in global emissions equivalent to the offset purchased.
2. Credibility criteria: Quality offsets must demonstrate additionality (the reduction would not have happened without the offset funding), permanence (reductions remain over the claimed period), no double counting (the same reduction is not claimed by more than one party) and minimal leakage (reductions in one place do not cause increased emissions elsewhere).
3. Co-benefits: Many offset projects deliver social and economic benefits-job creation, local development, technology transfer and improved livelihoods-especially in developing regions.
4. Example: A company unable to cut 100 tonnes of CO2 in the near term may finance a project that reduces 100 tonnes elsewhere (for instance, replacing kerosene lanterns with solar lighting in a community). By purchasing those offsets, the company funds the emission reduction and can account for the offset against its own emissions.

Carbon tax

Carbon tax is a fiscal instrument that levies a charge on the carbon content of fossil fuels or on greenhouse gas emissions. It is an alternative to market-based cap-and-trade systems and aims to internalise the social cost of carbon, thereby encouraging emission reductions.

1. Mechanism: A tax is imposed per unit of CO2 (or CO2e) emitted. Over time the tax rate may be increased to incentivise deeper decarbonisation and provide price signals for investment in low-carbon technologies.
2. Advantages: Predictability of price, relative ease and speed of implementation, transparency and lower susceptibility to market manipulation compared with complex trading schemes.
3. Policy design elements: Governments may design carbon taxes with rebates, targeted compensation for vulnerable households, or revenue recycling to support green investment and a just transition.

Geoengineering: large-scale intervention concepts

Geoengineering refers to deliberate, large-scale interventions in the Earth system to counteract climate change. Most geoengineering approaches are experimental or theoretical and raise ethical, geopolitical and ecological concerns. They are generally classified into two categories: solar radiation management (SRM) and carbon dioxide removal (CDR).

Examples of proposed geoengineering methods

1. Stratospheric aerosol injection (copying volcanic eruptions): Injecting sulphur-containing aerosols into the stratosphere to increase the planet's reflectivity, mimicking volcanic cooling. This is an SRM method that could lower global temperatures quickly but has risks for regional climates, precipitation patterns and stratospheric chemistry.
2. Space-based reflectors (mirrors in space): Deploying reflective objects or mirrors between the Sun and Earth to reduce incoming solar radiation. This is technologically challenging and extremely expensive, and it raises governance issues.
3. Ocean iron fertilisation (sea-seed iron): Adding iron to certain ocean regions to stimulate phytoplankton blooms that absorb CO2 and, when they die, transport carbon to the deep ocean. The efficacy, permanence and ecological risks (including harmful algal blooms and impacts on marine food webs) are uncertain and contentious.
4. Marine cloud brightening (whitening clouds): Using vessels to spray seawater to increase cloud droplet concentration and cloud albedo, thereby reflecting more sunlight. This is an SRM concept with regional effects and uncertain climate and environmental consequences.
5. Direct air capture and artificial trees: Devices that chemically absorb CO2 from ambient air (sometimes called artificial trees). Captured CO2 may be released in concentrated form for utilisation or stored geologically. This is a CDR approach with clear potential, though current costs and energy requirements remain significant.

Considerations and risks of geoengineering

• Unintended consequences: Large-scale interventions can alter precipitation patterns, regional climates and ecosystems in unpredictable ways.
• Moral hazard and governance: Reliance on geoengineering may reduce incentives for emissions reductions and raises questions about who decides deployment, liability and compensation for harm.
• Reversibility and termination risks: Some SRM methods require continuous maintenance; abrupt termination could cause rapid warming.
• Research needs: Robust scientific understanding, regulatory frameworks and international cooperation are essential before any real-world deployment.

Commercial and practical uses of captured CO2

• Enhanced oil recovery (EOR): Injecting CO2 into oil reservoirs to increase extraction; historically one driver for CO2 capture and transport infrastructure.
• Industrial uses: CO2 can be used in greenhouses to enhance plant growth, in the manufacture of dry ice, and as a feedstock in processes that create chemicals, fuels and building materials.
• Mineralisation and construction materials: CO2 can be mineralised into stable carbonates and incorporated into concrete and other building products, producing long-lived carbon storage.

Quality and permanence considerations for sequestration and offsets

Any carbon sequestration solution-whether natural, engineered storage, or offset project-should be evaluated for:

• Permanence: How long the carbon will remain out of the atmosphere (years, decades, centuries or longer).
• Additionality: Whether the action genuinely causes reductions that would not have occurred otherwise.
• Leakage: The risk that emissions are displaced to other locations or sectors.
• Measurability and verifiability: Whether reductions and storage can be accurately measured, monitored and independently verified.
• Co-benefits and safeguards: Impacts on biodiversity, water, livelihoods and human rights should be assessed and managed.

Policy, markets and international context

Mitigation strategies for carbon combine technical options with policy instruments such as carbon taxes, emissions trading systems, regulations, subsidies for low-carbon technologies and market mechanisms for credits and offsets. International frameworks (for example, commitments under the United Nations Framework Convention on Climate Change and mechanisms developed in response to the Kyoto Protocol) provide governance and accounting rules. Multilateral and national policies must work together to ensure environmental integrity, fairness and support for development objectives.

Practical notes and examples

• Industrial pilots and commercial CCS projects exist in power, cement, steel and chemical sectors; geological storage projects have demonstrated long-term trapping mechanisms in multiple locations.
• Blue carbon restoration projects (mangrove planting, wetland restoration) can deliver both mitigation and adaptation benefits for coastal communities.
• Carbon markets and exchanges trade credits and offsets; trading volumes and market values change over time. Market participants include project developers, investors, regulated entities and voluntary buyers.

Final summary

Carbon sequestration is a multi-pronged field that includes natural biological sinks, engineered capture and storage, market-based instruments and, for the future, carefully governed research into geoengineering. Each option has a role, limitations and risks. Effective climate mitigation requires combining rapid emissions reductions with credible, transparent and well-governed carbon sequestration and removal where necessary-ensuring environmental integrity, social co-benefits and international cooperation.