Sequestration of Atmospheric Carbon Dioxide as Inorganic Carbon under Semi-Arid Forests

Sequestration of carbon through forestation has been proposed to reduce rising atmospheric CO2 levels. But only organic carbon in the forest has so far been considered. Inorganic carbon storage (carbonate salts) in semi-arid forests, precipitated in the unsaturated zone (USZ), is of greater importance for long term sequestration of global CO2. Extrapolating data from the Yatir forest in Israel, we suggest that planting trees globally in semi-arid regions has the potential for increasing sequestration of atmospheric carbon dioxide by ~1 billion tons of atmospheric CO2/year(1 Pg CO2 yr -1 ). We stress the need for more accurate estimates, based on future worldwide data, on the rate of such precipitation of inorganic carbon. Still, our present extrapolated estimate represents ~5% of the current rate of increase of 20 billion tons of atmospheric CO2/year. That is, based on the Yatir data alone, sequestration of atmospheric CO2 as inorganic carbon under semi-arid forests may represent a sustainable and economic method to help suppress the rate by which CO2 is increasing in the atmosphere. Semi-arid regions, which comprise ~17% of the global land surface, are generally characterized by marginal agriculture and herding. Low-cost and low-tech afforestation can offer employment in these impoverished regions that are otherwise characterized by few opportunities. The present extended abstract is written as a short opinion piece, without figures and tables, summarizing results from our previously published journal articles.