Why in NEWS
Scientists are investigating Stratospheric Aerosol Injection (SAI) — a bold, volcano-inspired geoengineering technique — as a potentially faster and more affordable way to cool the planet amid intensifying climate change.
Key Concepts Simplified
| Term | Definition |
|---|---|
| Stratospheric Aerosol Injection (SAI) | A solar geoengineering method that injects reflective particles into the stratosphere to reflect sunlight and cool the Earth. |
| Solar Radiation Modification | Techniques aimed at reducing the amount of solar energy absorbed by Earth. |
| Albedo | The reflectivity of Earth’s surface; higher albedo means more sunlight is reflected away. |
| Sulfate Aerosols | Tiny particles commonly used in SAI, which mimic the cooling effect of volcanic eruptions. |
The Science Made Simple
- Inspired by Volcanoes: When Mount Pinatubo erupted in 1991, it released aerosols into the stratosphere, lowering global temperatures by 0.5°C for nearly a year.
- How SAI Works:
- Reflective particles (like sulfates or calcium carbonate) are released into the stratosphere (10–50 km).
- These particles scatter sunlight, increasing Earth’s albedo, and temporarily cool the planet.
Potential vs. Problems
| Aspect | Details |
|---|---|
| Effectiveness | More stable than lower-atmosphere methods (particles remain for months/years); stronger effects in polar regions. |
| Environmental Risks | – Ozone depletion – Acid rain from sulfur – Uneven cooling (weaker in tropics) – Disrupted precipitation patterns |
| Limitations | – Doesn’t reduce CO₂ levels – Alters atmospheric chemistry – Potential monsoon disruption |
Other Solar Radiation Modification Techniques
| Method | Description | Key Features |
|---|---|---|
| Marine Cloud Brightening (MCB) | Sprays fine seawater droplets into low-altitude ocean clouds to increase reflectivity. | – Localized & reversible – Weather-dependent – Technically complex |
| Space Sunshades | Deploys mirrors/screens in space (e.g., at Lagrange Point 1) to block sunlight. | – Large-scale – High cost – Physically challenging implementation |
| Cirrus Cloud Thinning (CCT) | Injects ice-nucleating particles to reduce the warming effect of cirrus clouds. | – Enhances heat escape – Reduces cloud persistence – Uses bismuth triiodide |
| Spraying Diamond Dust | Releases nanodiamonds into the stratosphere to reflect sunlight. | – Highly reflective – Chemically inert – Innovative but experimental |
In a Nutshell
Mnemonic: “Pinatubo’s Mirror: Reflect, Not Repair!”
SAI is like giving Earth a giant sunshade — it cools, but doesn’t clean up the mess (CO₂)!
Prelims Practice Questions
- Which of the following best describes Stratospheric Aerosol Injection (SAI)?
A) Carbon capture technology
B) Solar panel-based energy system
C) Solar radiation management method
D) Ocean fertilization strategy - Mount Pinatubo’s eruption in 1991 is linked to SAI because:
A) It caused mass extinction
B) It decreased Earth’s temperature using sulfate aerosols
C) It released large methane volumes
D) It created a hole in the ozone layer - Which of the following is a potential risk of SAI?
A) Enhanced photosynthesis
B) Increased biodiversity
C) Disruption of global rainfall patterns
D) Strengthening of tropical storms
Mains Practice Questions
- Discuss the mechanism and implications of Stratospheric Aerosol Injection as a climate change mitigation strategy. (UPSC GS3 – Climate Change)
- Geoengineering offers short-term relief but poses long-term risks. Critically analyze with reference to SAI.
Answers & Explanations
| Q No. | Answer | Explanation |
|---|---|---|
| 1 | C | SAI is a form of solar radiation management, aiming to reflect sunlight. |
| 2 | B | Mount Pinatubo’s eruption lowered global temperatures by 0.5°C via aerosols. |
| 3 | C | SAI can alter rainfall and monsoon patterns, causing regional imbalances. |
