Table 1.

Comparison of different land- or ocean-based technologies.

Type	Earth system	Mechanism	Measure	Advantage	Disadvantage
Afforestation and reforestation	Land	Photosynthesis	Mixed plantation; Plantation management	Ecological and economic benefits	Long growth cycle; Large land occupation
Soil carbon sequestration	Land	Photosynthesis; Microbial CO2 fixation	Fertilization and organic amendments; No-tillage systems; Crop rotation, Cover cropping	Large carbon sink capacity; Improvement of land quality	Availability of suitable land
Biochar	Land	Photosynthesis; Physicochemical process	High-temperature pyrolysis and hydrothermal carbonization of biomass or other organic matter	Improving soil fertility; Reducing the use of chemical fertilizer; High stability	High-temperature preparation process
Bioenergy with carbon capture and storage	Land	Photosynthesis; Physicochemical process	Pyrolysis, gasification, fermentation, or combustion of biomass or other organic matter to produce bioenergy; Carbon capture technologies	Renewable, low pollution; A wide range of raw material sources	High cost; Land occupation; Part of the bioenergy is made from food crops
Enhanced weathering	Land	Physicochemical process	Addition of carbonate or silicate	Increasing the essential nutrients; Mitigation of ocean acidification	High cost; Increasing soil pH
Ocean alkalinization	Ocean	Physicochemical process	Addition of alkaline minerals	Mitigation of ocean acidification	Increasing ocean pH; Affecting marine communities
Ocean fertilization	Ocean	Photosynthesis	Addition of iron, nitrogen, or phosphorus	Increasing productivity of marine life	Red tides; Production of other toxic acids; Lower oxygen levels in the ocean