Mitigation Options for Reducing Net Greenhouse Emissions

Climate mitigation refers to actions that reduce the sources of greenhouse gas emissions or enhance the sinks that absorb them, with the aim of slowing the rate of climate change.

Categories of Mitigation

Mitigation strategies can be grouped into four major categories:

Energy Supply Mitigation

Renewable Energy

Replacing fossil fuel combustion with zero- or low-emission energy sources:

Nuclear Energy

• Low operational emissions per kWh
• Provides reliable base-load power
• Concerns: nuclear waste storage, capital cost, public acceptance, Chernobyl/Fukushima incidents

Energy Demand Mitigation

Building and Industry Efficiency

• Better insulation, double glazing and efficient HVAC systems reduce heating/cooling energy needs
• LED lighting replaces incandescent (~6× more efficient)
• Industrial process optimisation, waste heat recovery
• Green building standards (e.g. 6-star energy rating)

Transport

• Electric vehicles (EVs) shifting energy demand to electricity sector (where renewables can decarbonise)
• Public transport, cycling and walking infrastructure
• Urban planning that reduces car dependence
• Fuel efficiency standards for new vehicles

Agriculture

• Reducing enteric fermentation from livestock through feed additives and breeding
• Precision fertiliser application to reduce N$_2$O emissions
• Water management in rice paddies
• Reducing food waste (embedded emissions in unconsumed food)

Carbon Sequestration (Land and Technology)

Natural Carbon Sinks

• Reforestation and afforestation: Restoring forests sequesters CO$_2$ in biomass
• Revegetation of degraded lands: Improves soil carbon stocks
• Wetland and mangrove restoration: High carbon density ‘blue carbon’ stores
• Soil carbon sequestration: No-till farming, biochar addition

Technology-Based Carbon Removal

• Carbon Capture and Storage (CCS): CO$_2$ captured at point of emission (power stations), compressed and stored in geological formations
• Bioenergy with CCS (BECCS): Grow bioenergy crops (absorbs CO$_2$), combust for energy, capture and store the CO$_2$ — theoretically creates negative emissions
• Direct Air Capture (DAC): Industrial machines extract CO$_2$ directly from ambient air — expensive but scalable in principle

Non-CO$_2$ Gas Reduction

• Methane from coal mines: Capture and use for energy
• F-gas phase-out: Replace HFCs in refrigeration with natural refrigerants (Kigali Amendment to Montreal Protocol)
• Nitrous oxide from agriculture: Optimise nitrogen fertiliser use; use slow-release fertilisers

Policy and Pricing Mechanisms

Mitigation strategies require policy support:
- Carbon pricing (carbon tax or emissions trading scheme): Creates financial incentive to reduce emissions
- Renewable energy targets and mandates: Drive investment in clean energy
- Fuel efficiency standards: Reduce transport emissions
- Building codes: Require energy-efficient construction
- International agreements: Paris Agreement (2015) commits nations to nationally determined contributions

Net Emissions vs. Gross Emissions

Net emissions = Gross emissions − Carbon sequestration

Mitigation strategies can reduce gross emissions (sources) or increase sequestration (sinks), or both. The Paris Agreement’s 1.5°C target requires global net zero emissions by approximately 2050.

EXAM TIP: VCAA may ask you to evaluate a mitigation strategy against sustainability principles. Apply the precautionary principle (urgent action given uncertainty about worst-case outcomes), intergenerational equity (emissions today harm future generations) and efficiency (compare cost per tonne CO$_2$e reduced). Always distinguish clearly between mitigation (reducing emissions/increasing sinks) and adaptation (adjusting to effects).