evidence: More recent estimates from Terrenoire et al. (2019) project that CO2 emissions from the global aviation sector will be responsible for up to 0.1 ∘C by the end of the century in the absence of mitigation action. [...] Figure 5a shows the impact of future international aviation emissions (beginning in 2020) on surface air temperature change throughout the 21st century. The contribution of CO2 emissions to future warming over time and in the year 2100 is slightly lower than that from the shipping sector (0.05 ∘C by 2100). However, the inclusion of non-CO2 climate pollutant emissions does not yield a net cooling effect for several decades as it does with shipping and reduces warming by the end of the century to 0.03 ∘C (note that we do not include the impacts on contrails and cirrus clouds here). For a few years, the net temperature impact from future aviation emissions is cooling but then quickly switches to warming and increases steadily through the end of the century (consistent with radiative forcing calculations in Unger et al. (2010) for constant year-2000 emissions). Similar to shipping, the cooling effect is dominated by the cooling precursor gas nitrogen oxide (Fig. 5b). By 2100, nitrogen oxides are responsible for a cooling of 0.02 ∘C, while the end-of-century contributions from all other non-CO2 climate pollutants (sulfur dioxide, organic carbon, carbon monoxide, and black carbon) are negligible.