Abstract
Drylands forestation has the potential for long-term sequestration of atmospheric CO2, based upon studies in Israel’s Yatir Forest. This is a 28 km2 planted Aleppo pine forest growing at the semi-arid timberline, having 280 mm average annual precipitation (with no irrigation or fertilization). The organic carbon sequestration rate (assumed representative of global drylands) was measured at Yatir to be ~550 g CO2 m-2 yr-1 (150 g C) organic carbon in the tree’s biomass. In addition, soil inorganic carbon (SIC), abstracted from atmospheric CO2, precipitates as roots exhale CO2 into the soil. The CO2 then combines with soil H2O to form bicarbonate (HCO3-), which in turn combines with soil Ca2+ to form calcite (CaCO3). Integrating our measured rate of inorganic carbon deposition to a representative 6 meter depth, we find that ~132 g CO2 m-2 yr-1 precipitates as calcite. Additionally, forestation facilitates the microbial precipitation of calcite in desert soils, which may attain approximately 40% of the total SIC. The potential maximal efficacy of global forestation for reducing global warming and ocean acidification depends on the maximal area available for sustainable forestation. In many dryland areas, plentiful water is available from immediately underlying local paleowater (fossil) aquifers. Using such water should enable a functional dryland forestation area of ~9.0 million km2. Following forestation, the potential total annual sequestration rate would be at least ~7.0 Gt CO2 yr−1; divided between 5.0 Gt CO2 yr−1 (organic) and 2.0 Gt CO2 yr−1 (inorganic); a respectable ~35% of the annual rate of atmospheric CO2 increase.
Presenters
Murray MoinesterEmeritus Professor of Physics, School of Physics and Astronomy, Department of Particle Physics, Tel Aviv University, HaMerkaz, Israel
Details
Presentation Type
Paper Presentation in a Themed Session
Theme
Technical, Political, and Social Responses
KEYWORDS
Carbon Sequestration, Drylands Forests, Climate Change, Fossil Water
