| Over the past decades, the geographical distribution of emissions of substances that alter the
atmospheric energy balance has changed due to economic growth and pollution regulations.
Here, we show the resulting changes to aerosol and ozone abundances and their radiative
forcing, using recently updated emission data for the period 1990-2015, as simulated by
seven global atmospheric composition models. The models broadly reproduce large-scale
changes in surface aerosol and ozone based on observations (e.g., -1 to -3%/yr in aerosols
over the US and Europe). The global mean radiative forcing due to ozone and aerosols
changes over the 1990-2015 period increased by +0.17 ±0.08 Wm−2, with approximately 1/3
due to ozone. This increase is more strongly positive than reported in IPCC AR5. The main
reasons for the increased positive radiative forcing of aerosols over this period are the
substantial reduction of global mean SO2 emissions, which is stronger in the new
emission inventory compared to the IPCC, and higher black carbon emissions. |