As noted in the introduction to this lesson, mitigation involves any action that prevents, limits, delays, or slows the rate of climate change. Mitigation may involve one of three types of action:
- direct interventions in the natural environment;
- direct interventions in the proximate causes; and
- indirect interventions through the driving forces.
Direct interventions in the natural environment involve sequestration, which can be defined as permanent storage of GHGs so they do not contribute to the greenhouse effect. Some sequestration techniques are more “natural,” while others take a high-tech geoengineering approach. Terrestrial sequestration occurs in forests, crops, and soils, which naturally store carbon but release it again as CO2 when people cut down forests, harvest crops, and disturb soils. Refraining from deforesting, planting carbon-fixing crops and not harvesting them, and promoting soil conservation maintains existing carbon stocks and grows those stocks in the future. Geoengineering approaches to sequestration, which presently are only experimental and not operational, include such massive undertakings as capturing CO2 and pumping it into the solid Earth or ocean sediments.
Realizing direct interventions in the proximate causes means getting people to change their activities so they either do not generate GHGs or produce lower emissions. Examples of direct interventions embrace ideas like using less electricity by turning off lights when not in the room or buying energy-efficient light bulbs. Other examples could involve individuals taking mass transit instead of driving to work, communities capturing and burning CH4 from their landfills instead of letting it escape to the atmosphere, or countries passing laws to eliminate the manufacture and use of CFCs (which actually did occur with the Montreal Protocol).
Indirect interventions that redirect the forces driving GHG emissions require making fundamental shifts in the way society operates. Examples include:
- Population: reaching zero population growth by harnessing one of the other drivers (e.g., through a cultural change making large families undesirable)
- Technology: investing in energy-smart technologies
- Economy: charging consumers for GHG emissions
- Institutions: adopting laws promoting dense development and mass transit
- Culture and behavior: changing energy-consumptive lifestyles