Our understanding of the warming effect of carbon dioxide in the atmosphere dates from the mid-19th century and, while the effect could not then be quantified, early 20th-century investigators considered that emissions from fossil fuel combustion might be beneficial in staving off future ice ages. Not until the 1970s did it become apparent that the impact was likely to be damaging. This chapter follows this historical path, describing our growing understanding of climate change, the parallel development of Earth-system modeling capabilities, and the process that culminated in the Paris Agreement. The need for a transition to nonfossil energy and the decarbonization of the global economy are discussed as essential foundations if negative-emissions technologies are to deliver global net-negative emissions in the second half of this century.
Negative Emissions Technologies for Climate Change Mitigation, 2023, pages 1-18,