The direct removal of carbon dioxide from the atmosphere.

Source: Minx, Jan C., William F. Lamb, Max W. Callaghan, Sabine Fuss, Jérôme Hilaire, Felix Creutzig, Thorben Amann et al. “Negative Emissions—Part 1: Research Landscape and Synthesis.” Environmental Research Letters 13, no. 6 (May 22, 2018): 063001.