Q1: Critically evaluate Solar Radiation Management (SRM) as a geoengineering approach to counter global warming. Do its potential benefits outweigh the environmental and ethical risks involved?
Analytical Focus for Answer
- Define SRM and describe major methods (Stratospheric Aerosol Injection, Marine Cloud Brightening, Cirrus Cloud Thinning, Space Mirrors).
- Assess scientific feasibility and cost efficiency (e.g., SAI cost estimates).
- Discuss environmental uncertainties: termination shock, regional rainfall disruption, and ethical concerns (e.g., governance without global consent).
- Conclude on whether SRM should complement or be excluded from mainstream mitigation strategies.
Model Answer
Introduction
- Definition and Scope: Solar Radiation Management (SRM) refers to deliberate interventions designed to reduce solar heating of Earth by reflecting sunlight or limiting its absorption, thereby temporarily offsetting global warming.
- Contextual Relevance: With global mitigation targets lagging and atmospheric CO₂ concentrations still rising, SRM has re-emerged as a controversial yet potentially rapid-response climate tool.
- Core Question: The debate centres on whether the climatic benefits of artificially cooling the planet outweigh the environmental, ethical, and governance challenges associated with such planetary-scale manipulation.
Body
1. Major SRM Methods:
- Stratospheric Aerosol Injection (SAI): Involves releasing aerosols like sulfur dioxide at 15–50 km altitude to reflect sunlight, mimicking volcanic eruptions; projected costs around $55 million annually per country for 30 nations, but with risks of “termination shock” if halted suddenly.
- Marine Cloud Brightening (MCB): Uses sea salt sprays to enhance cloud reflectivity, showing promise for protecting coral reefs yet posing uncertainties in regional precipitation impacts.
- Cirrus Cloud Thinning: Targets high-altitude clouds that trap heat, allowing more infrared radiation to escape; still in experimental phase with uncertain large-scale implications.
- Space-Based Reflectors: Proposes mirrors or sunshades at Lagrange Point 1 to block solar radiation; technically complex and economically prohibitive at current capacities.
2. Scientific Feasibility and Cost Efficiency:
- Rapid Cooling Potential: SRM could reduce global temperatures within years—unlike slow-acting carbon removal methods.
- Cost Advantage: SAI is considered economically feasible relative to carbon removal options, which cost $100–$600 per tonne of CO₂.
- Limitation: SRM does not reduce atmospheric greenhouse gases and requires indefinite maintenance to sustain cooling effects.
3. Environmental and Ethical Risks:
- Termination Shock: Sudden cessation could cause abrupt temperature spikes, disrupting ecosystems and agriculture.
- Hydrological Imbalance: Regional monsoon and rainfall patterns may shift, threatening food security in tropical regions like South Asia.
- Polar Ineffectiveness: SRM is less effective during polar winters when sunlight is absent, limiting its global uniformity.
- Governance Vacuum: Lack of global consensus could lead to unilateral deployment, sparking geopolitical tensions.
- Moral Hazard: Overreliance on SRM might weaken political will for emission reductions, delaying decarbonization.
Conclusion
- Balanced Assessment: SRM offers potential for short-term temperature stabilization but introduces immense uncertainties and equity concerns.
- Policy Direction: It should not substitute but rather complement emission mitigation and carbon removal strategies under strict international regulation and scientific oversight.
- Ethical Imperative: The precautionary principle demands that humanity avoid planetary-scale experiments without global consent or robust risk assessment.
Q2. Examine the concept of glacial geoengineering. How viable are such interventions in slowing polar ice loss and mitigating sea-level rise?
Analytical Focus for Answer
Answer Focus Points:
- Define glacial geoengineering and mention key techniques (sea curtains, microbeads, basal water removal).
- Evaluate cost, ecological side effects, and scalability.
- Discuss global ethical and environmental governance challenges.
- Conclude on the trade-off between technological intervention and sustainable adaptation measures.
Model Answer
Introduction
- Definition: Glacial geoengineering refers to large-scale, deliberate interventions aimed at slowing the melting of glaciers and ice sheets to limit global sea-level rise.
- Context: Accelerating ice loss due to feedback loops—such as declining albedo and permafrost methane emissions—has intensified the need for technological approaches beyond conventional mitigation.
- Relevance: The IPCC projects sea-level rise between 0.43 and 0.84 meters by 2100, underscoring the urgency for innovative responses.
Body
- Key Techniques: Methods include sea curtains or sediment berms to block warm ocean water, basal hydrology modification to remove subglacial meltwater and slow ice flow, and surface thickening by pumping seawater to freeze over ice caps.
- Reflectivity Enhancement: Hollow glass microspheres and cirrus cloud thinning are explored to increase albedo and radiative cooling.
- Viability and Challenges: These techniques face massive costs (over $1 billion per km of barrier), technical complexities, and ecological risks such as marine ecosystem disruption and ecotoxicity from reflective materials.
- Governance Issues: Global consensus on regulating such interventions remains weak, heightening concerns of unilateral experimentation and moral hazard that may dilute emission reduction efforts.
Conclusion
- While glacial geoengineering presents innovative potential to mitigate ice loss, it remains highly experimental.
- It should serve as a supplementary measure, not a substitute for sustained decarbonization and ecosystem-based adaptation.