Sequestering Atmospheric Carbon Dioxide

The abrupt climate change, attributed to increase in atmospheric concentration of CO2 and other greenhouse gases, has necessitated identification of technological options to sequester CO2 into other long-lived pools. Other viable pools for C sequestration include geologic, oceanic, and the terrestrial. There is also a potential to convert CO2 into stable minerals. There are geoengineering techniques of CO2 capture and storage into old oil wells to enhance oil recovery (EOR) and access coalbed methane (CBM), store in saline aquifers and sedimentary rocks, and combine it with basalt where it goes through chemical transformations. Geoengineering techniques have relatively high sink capacity and also high costs. Further, geoengineering techniques require measurement, monitoring, and verification (MMV) protocols. In contrast, C sequestration in terrestrial ecosystems (soil and biota) is based on the natural process of photosynthesis, and humification of biosolids applied to the soil. Terrestrial pools have relatively lower sink capacity, but are cost-effective and have numerous ancillary benefits. Total CO2 drawdown is estimated at reduction in 50 ppm of atmospheric concentration over 5 decades. Increasing C pool in agricultural soils is essential to advancing food security, and that in degraded/desertified soils to improve the environment. Rather than either/or scenarios, both strategies of C sequestration via geoengineering and terrestrial strategies have specific niches which need to be carefully and objectively identified and implemented. The terrestrial C sequestration is a win-win strategy because of its numerous benefits, especially its positive impact on food security while mitigating climate change and improving the environment.