1. Introduction to Geoengineering

Geoengineering refers to large-scale, deliberate interventions in the Earth’s climate system to counteract climate change. It is often compared to using a thermostat for the planet—adjusting global “settings” to maintain a livable environment.

Analogy:
Imagine Earth as a greenhouse. Geoengineering is like installing extra fans, shades, or dehumidifiers to control temperature and humidity when natural ventilation is not enough.

2. Major Approaches in Geoengineering

A. Solar Radiation Management (SRM)

Goal: Reflect a portion of sunlight back into space to cool the planet.

Techniques & Examples:

  • Stratospheric Aerosol Injection: Spraying tiny reflective particles (like sulfur dioxide) into the upper atmosphere.
    Analogy: Like adding a thin layer of sunscreen to Earth’s atmosphere.
  • Marine Cloud Brightening: Spraying sea salt into clouds to make them more reflective.
    Real-world example: Field tests off the coast of Australia aim to protect the Great Barrier Reef.
  • Space Mirrors: Deploying large reflectors in orbit to reduce incoming solar energy.
    Analogy: Like using a sunshade in a car windshield.

B. Carbon Dioxide Removal (CDR)

Goal: Actively remove CO₂ from the atmosphere.

Techniques & Examples:

  • Direct Air Capture (DAC): Machines that filter CO₂ directly from the air.
    Real-world example: Climeworks’ Orca plant in Iceland.
  • Bioenergy with Carbon Capture and Storage (BECCS): Growing biomass, burning it for energy, and capturing the CO₂ emissions underground.
  • Ocean Fertilization: Adding nutrients (like iron) to oceans to stimulate phytoplankton growth, which absorbs CO₂.
    Analogy: Fertilizing a garden to grow more plants that absorb carbon.

3. Emerging Technologies

A. Enhanced Weathering

  • Process: Spreading crushed silicate rocks on land to chemically react with CO₂ and form stable carbonates.
  • Recent Development: Pilot projects in the UK and Australia are testing basalt dust on croplands.

B. Artificial Intelligence (AI) in Geoengineering

  • Drug & Material Discovery: AI models accelerate the search for efficient catalysts for carbon capture and new reflective materials for SRM.
  • Climate Modeling: AI improves the prediction of geoengineering impacts by analyzing vast climate datasets.

C. Marine Geoengineering

  • Seaweed Farming: Large-scale kelp farms absorb CO₂ and can be sunk to the ocean floor for long-term storage.
  • Alkalinity Enhancement: Adding alkaline substances to oceans to increase their capacity to absorb CO₂.

4. Real-World Examples

  • Mount Pinatubo Eruption (1991): Natural analog for SRM. The eruption injected millions of tons of sulfur dioxide into the stratosphere, cooling Earth by about 0.5°C for two years.
  • Climeworks Orca Plant (2021): World’s largest direct air capture facility, capable of removing 4,000 tons of CO₂ per year.

5. Common Misconceptions

Misconception Reality
Geoengineering is a quick fix for climate change. It is not a substitute for emissions reductions and carries risks and uncertainties.
SRM and CDR are the same. SRM manages sunlight, while CDR removes greenhouse gases.
Geoengineering has no side effects. Potential risks include changes in rainfall patterns, ocean acidification, and geopolitical tensions.
Once started, geoengineering can be stopped easily. Sudden cessation could cause rapid climate rebound, known as “termination shock.”

6. Latest Discoveries & Research

  • AI-Driven Carbon Capture Materials:
    A 2023 study in Nature (https://www.nature.com/articles/s41586-023-05837-2) reports the use of machine learning to discover new metal-organic frameworks (MOFs) that capture CO₂ more efficiently than previous materials.
  • Marine Cloud Brightening Trials:
    The Australian government funded real-world tests in 2022 to assess the feasibility of cloud brightening for coral reef protection.
  • Enhanced Weathering Field Trials:
    A 2021 pilot in the UK demonstrated that basalt dust application increased soil carbon storage and crop yields.

7. Quiz Section

1. What is the primary goal of Solar Radiation Management?
a) Remove CO₂ from the atmosphere
b) Reflect sunlight to cool the planet
c) Increase ocean alkalinity
d) Grow more trees

2. Which of the following is a real-world example of direct air capture?
a) Mount Pinatubo eruption
b) Climeworks Orca plant
c) Marine cloud brightening
d) Ocean fertilization

3. What is a potential risk of abruptly stopping SRM interventions?
a) Ocean acidification
b) Termination shock
c) Increased crop yields
d) None of the above

4. How does enhanced weathering remove CO₂?
a) By growing more trees
b) By chemical reaction with crushed rocks
c) By reflecting sunlight
d) By burning fossil fuels

5. What role does AI play in geoengineering research?
a) Predicting climate impacts
b) Discovering new materials
c) Optimizing intervention strategies
d) All of the above

8. Summary Table

Approach Example Technique Key Benefit Main Risk
SRM Stratospheric aerosol injection Rapid cooling Disrupted rainfall
CDR Direct air capture Permanent CO₂ removal High cost, energy use
Enhanced Weathering Basalt dust on cropland Soil improvement, carbon storage Unknown long-term effects
Marine Geoengineering Seaweed farming CO₂ absorption Ecosystem impacts

9. References

  • Nature, 2023: “Machine learning–accelerated discovery of CO₂ capture materials.” Link
  • Australian Government, 2022: “Field trials of marine cloud brightening for reef protection.”
  • Royal Society, 2021: “Enhanced weathering field trials in the UK.”

End of Study Notes