TY - JOUR

T1 - Benefits of net-zero policies for future ozone pollution in China

AU - Liu, Z.

AU - Wild, O.

AU - Doherty, R. M.

AU - O'Connor, Fiona M.

AU - Turnock, S. T.

PY - 2023/11/6

Y1 - 2023/11/6

N2 - Net Zero emission policies principally target climate change, but may have a profound influence on surface ozone pollution. To investigate this, we use a chemistry-climate model to simulate surface ozone changes in China under a Net Zero pathway, and examine the different drivers that govern these changes. We find large monthly mean surface ozone decreases of up to 16 ppb in summer and small ozone decreases of 1 ppb in winter. Local emissions are shown to have the largest influence on future ozone changes, outweighing the effects of changes in emissions outside China, changes in global methane concentrations and a warmer climate. Impacts of local and external emissions show strong seasonality, with the largest contributions to surface ozone in summer, while changes in global methane concentrations have a more uniform effect throughout the year. We find that while a warmer climate has a minor impact on ozone change compared to the Net Zero scenario, it will alter the spatial patterns of ozone in China, leading to ozone increases in the south and ozone decreases in the north. We also apply a deep learning model to correct biases in our ozone simulations, and to provide a more robust assessment of ozone changes. We find that emission controls may lead to a surface ozone decrease of 5 ppb in summer. This is smaller than that simulated with the chemistry-climate model, reflecting overestimated ozone formation under present-day conditions. Nevertheless, this assessment clearly shows that the strict emission policies needed to reach Net Zero will have a major benefit in reducing surface ozone pollution and the occurrence of high ozone episodes, particularly in high-emission regions in China.

AB - Net Zero emission policies principally target climate change, but may have a profound influence on surface ozone pollution. To investigate this, we use a chemistry-climate model to simulate surface ozone changes in China under a Net Zero pathway, and examine the different drivers that govern these changes. We find large monthly mean surface ozone decreases of up to 16 ppb in summer and small ozone decreases of 1 ppb in winter. Local emissions are shown to have the largest influence on future ozone changes, outweighing the effects of changes in emissions outside China, changes in global methane concentrations and a warmer climate. Impacts of local and external emissions show strong seasonality, with the largest contributions to surface ozone in summer, while changes in global methane concentrations have a more uniform effect throughout the year. We find that while a warmer climate has a minor impact on ozone change compared to the Net Zero scenario, it will alter the spatial patterns of ozone in China, leading to ozone increases in the south and ozone decreases in the north. We also apply a deep learning model to correct biases in our ozone simulations, and to provide a more robust assessment of ozone changes. We find that emission controls may lead to a surface ozone decrease of 5 ppb in summer. This is smaller than that simulated with the chemistry-climate model, reflecting overestimated ozone formation under present-day conditions. Nevertheless, this assessment clearly shows that the strict emission policies needed to reach Net Zero will have a major benefit in reducing surface ozone pollution and the occurrence of high ozone episodes, particularly in high-emission regions in China.

KW - Air quality

KW - Ozone

KW - Oxidation

KW - Air pollution

KW - Climate change

KW - Net zero

KW - Atmospheric chemistry

KW - Atmospheric modelling

U2 - 10.5194/egusphere-2023-230

DO - 10.5194/egusphere-2023-230

M3 - Journal article

VL - 23

SP - 13755

EP - 13768

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7316

IS - 21

ER -