Does the location of aircraft nitrogen oxide emissions affect their climate impact?

We present results from 112 one‐year global chemistry‐transport model integrations: a base case, then variants with extra aircraft nitrogen oxide (NO x ) emissions added to specific regions in the first month (July). The NO x stimulates ozone (O 3 ) production and methane (CH 4 ) destruction. Responses vary spatially: low background NO x regions are most sensitive. Integrated (100‐year time horizon) radiative forcings (IRF) are calculated. Net (O 3 + CH 4 ) IRFs for July aviation NO x are generally negative: the global average, weighted by emissions, is −1.9 mWm −2 yr (TgNO 2 ) −1 . The positive IRF associated with the short‐term O 3 increase (4.1 mWm −2 yr (TgNO 2 ) −1 ) is overwhelmed by the effects of the long‐term CH 4 decrease. Aircraft NO x net IRFs are spatially variable, with July values over the remote Pacific approximately balancing the IRF associated with aviation CO 2 emissions (28 mWm −2 yr (TgNO 2 ) −1 ). The overall climate impact of global aviation is often represented by a simple multiplier for CO 2 emissions. These results show that this is inappropriate.