Mitigating Impacts of Climate Change

• Radiative Forcing: Mitigation aims to reduce the positive radiative forcing caused by human activities. By lowering the concentration of GHGs, less longwave radiation is trapped in the atmosphere, which helps stabilize global temperatures.

• Carbon Cycle Rebalancing: Human activity has accelerated the transfer of carbon from the lithosphere (fossil fuels) to the atmosphere. Mitigation strategies seek to restore balance by slowing this transfer and increasing the rate of carbon return to long-term storage.

• The 1.5 Degree Target: Modern mitigation efforts are guided by the principle of limiting global average temperature increases to $1.5^{\circ}C$ above pre-industrial levels to avoid the most catastrophic ecological tipping points.

Carbon Capture and Storage (CCS)

• Capture: This technological process involves separating $\text{CO}_2$ from industrial and energy-related sources before it enters the atmosphere. Modern systems can capture up to 90% of emissions from a single point source.
• Transport: Once captured, the gas is compressed into a liquid-like state (supercritical $\text{CO}_2$) and transported via pipelines or ships to a suitable storage site.
• Storage: The $\text{CO}_2$ is injected into deep underground geological formations, such as depleted oil and gas fields, deep saline aquifers, or unmineable coal seams, where impermeable rock layers prevent it from escaping.

Biological Sequestration

• Afforestation and Reforestation: Planting trees in new areas or restoring degraded forests creates natural carbon sinks. Trees absorb $\text{CO}_2$ during photosynthesis and store it in their biomass and the surrounding soil.

Policy and Economic Instruments

• Cap and Trade: Governments set a limit (cap) on the total level of emissions and issue permits. Entities that emit less than their allowance can sell their excess 'carbon credits' to those who exceed their limits, creating a financial incentive for reduction.

• Identify the Scale: When discussing mitigation, always specify if the strategy is individual (e.g., reducing meat consumption), national (e.g., carbon taxes), or international (e.g., the Paris Agreement).

• The CCS Chain: If asked about Carbon Capture and Storage, ensure you mention all three distinct phases: capture, transport, and storage. Missing one phase often results in lost marks.

• Policy Comparison: Be prepared to distinguish between the Kyoto Protocol (legally binding for some, focused on 1990 levels) and the Paris Agreement (voluntary targets for all, focused on limiting warming to $1.5^{\circ}C$).

• The 'Silver Bullet' Fallacy: A common mistake is assuming one technology, like CCS, can solve climate change alone. Effective mitigation requires a 'wedge' approach—combining many different strategies simultaneously.

• Mitigation vs. Adaptation Confusion: Students often label building sea walls as mitigation. Remember: if it doesn't reduce GHGs in the atmosphere, it is adaptation, not mitigation.

• Carbon Neutral vs. Net Zero: Carbon neutral often refers to balancing emissions with offsets, while Net Zero implies a deep reduction in emissions across the entire value chain, with only residual emissions being removed.