The growth rate of climate forcing due to human-caused GHGs increased over 20 % in the past decade mainly due to resurging growth of atmospheric CH4, thus making it increasingly difficult to achieve targets such as limiting global warming to 1.5 °C or reducing atmospheric CO2 below 350 ppm. To achieve such targets now require negative emissions, i.e., extraction of CO2 from the atmosphere. If rapid phasedown of fossil fuel emissions begins soon, most of the necessary CO2 extraction can take place via improved agricultural and forestry practices, including steps to improve soil fertility by increasing its carbon content and reforestation (1).

1) Hansen, J, et al, Young People’s Burden: Requirement of Negative CO2 Emissions, Earth Syst. Dynam. Discuss., submitted for Publication (2016)