Chapter 2 has a plot of our understanding of the impact of all natural and human causes on the change in temperature: https://nca2018.globalchange.gov/img/figure/figure2_1.png
It's pretty clear (according to the models) that the human created aerosols combat a fair chunk of the increase caused by carbon emissions (around 0.7 deg C at the moment, which is substantial; we'd have already been around 2 deg C without it). Is deliberately increasing the amount of aerosols in the atmosphere a viable path forward? Is this economically feasible and safe? Can this be used to bring us back to the pre-industrial temperature levels?