Numerical simulations with a global chemistry-climate model show that the emissions from the transport sectors (land-based transport, shipping and aviation) have important impacts on atmospheric aerosol and climate. Several numerical simulations were performed with the global chemistry-climate model EMAC, coupled to the aerosol model MADE, to quantify the effect of transport emissions on atmospheric aerosol and climate. The emission data adopted in the model represent the conditions of the year 2000 and year 2030 for four different scenarios.
The model results for the year 2000 show that the land-transport sector is a major source of large-scale particulate matter pollution in the United States, Europe and the Arabian Peninsula, contributing up to 70% of the black carbon concentration at the ground level. Shipping emissions have a large impact along the major routes of the Northern Pacific and Atlantic Ocean and are responsible for about 40-60 % of ground-level aerosol sulfate and nitrate concentrations in these regions. Aviation emissions have little impact on aerosol mass concentration, but they can significantly increase the particle number concentration at cruise altitude (10-12 km).
The model simulations further suggest that the aerosol perturbations induced by the transport sectors can significantly alter the Earth’s radiation budget, mostly due to modification of cloud microphysical properties. In 2000, the largest impact is found for the shipping sector, which induces an aerosol radiative effect in the range -222 to -153 mW/m2 on global average. This effect is much larger than the concurrent opposite effects induced by CO2 and ozone from the same source. Significant aerosol-induced cooling effects are also found for the land-transport and the aviation sectors.
The future scenarios project a general decrease of land-transport and shipping impacts on global scale. Land-transport-induced pollution, however, shows remarkable regional differences, decreasing in Europe and North America while increasing in Southeast Asia. The aviation effects are projected to be larger than in 2000, due to continuously growing traffic volumes.
Righi, M., Hendricks, J., and Sausen, R.: The global impact of the transport sectors on atmospheric aerosol: simulations for year 2000 emissions, Atmos.Chem.Phys., 13, 9939-9970, doi:10.5194/acp-13- 9939-2013, 2013.
Righi, M., Hendricks, J., and Sausen, R.: The global impact of the transport sectors on atmospheric aerosol in 2030 – Part 1: Land transport and shipping, Atmos.Chem.Phys., 15, 633-651, doi:10.5194/acp-15-633-2015, 2015.