An estimate on the rainout of atmospheric CO_2

摘要

The CO2 in the atmosphere is in contact with water vapor and rain droplets forming CO2·H2O, HCO -3 and CO 2- 3. Global precipitation is about 505×10 15 kg/a. Based on theoretical calculation for unpolluted air and measurement observations, we estimated that 100—270×10 12 gC/a are scavenged from the air by global precipitation. This roughly equals carbon emissions from volcanic sources or 2—6 per cent of current CO2 emissions. An inventory-based estimate on carbon removal in northwestern Europe supports the above calculation on global scale. With increasing CO2 concentration in the air, precipitation scavenging may increase.