The Paris Climate Agreement and the Importance of climate engineering: Stopping global warming requires Net-Zero CO2 emissions. Since it is not yet foreseeable that all emissions can be avoided by mid-century, the Net-Zero target set in the Paris Climate Agreement implies the use of CO2 removal methods that can be described as a category of climate engineering. Optimistic emission reduction scenarios assume that by mid-century, 5 to 15% of today's emissions will have to be offset by CO2 removal as difficult-to-avoid residual emissions. So-called "nature-based" solutions alone will not be sufficient to achieve this. Technical approaches will also have to be applied at large scale if the climate targets are to be achieved. None of these methods is ready for large-scale deployment today. Public research is needed and the societal debate on how to deal with residual emissions must begin quickly so that appropriate methods can be developed in time, well-informed societal decisions can be made about their eventual deployment, and mechanisms can be devised to regulate such deployment responsibly.