How can biological systems contribute to carbon capture and storage?

Biological carbon capture leverages photosynthesis and other carbon-fixing processes: Terrestrial approaches: Afforestation/reforestation - forests sequester 2-4 tons C/ha/year; permanence and monitoring challenges. Soil carbon - regenerative agriculture, biochar application increase soil organic carbon; BECCS (Bioenergy with Carbon Capture and Storage) - biomass energy with geological CO2 storage; net-negative when sustainable biomass sourced. Aquatic approaches: Algal cultivation - high productivity (50+ tons/ha/year dry weight); can couple to wastewater treatment and CO2 point sources; products include biofuels, feed, chemicals; ocean fertilization controversial. Seaweed farming - kelp and macroalgae aquaculture; carbon sequestration through sinking or processing. Marine microbiome - enhancing natural ocean carbon pump. Enhanced weathering: Microbially-enhanced mineral carbonation - accelerate natural silicate weathering; permanent mineral carbon storage; bioengineering approaches to enhance microbial contributions. Challenges: Scale required for climate impact; monitoring, reporting, verification; permanence; competition with food production; life cycle impacts; economic viability without carbon pricing. Integration with broader climate strategies essential.