The importance of integrated assessments in advancing pollutants mitigation has been emphasized worldwide. Many environmental issues such as air pollution, climate change, waste management are interrelated and therefore we can reap various benefits through integrated planning. In order to support these efforts we develop an integrated assessment model of climate and environment (ICE). The model applies a stock-turnover method for projection of activity variables such as the number of cars by type, fuel, size, and model-year, gross floor area of buildings by building code and the year of construction, and organic carbon of landfill. Applying variants of the IPAT (impact, population, affluence, technology) identify, emissions from socioeconomic activities including air pollutants, greenhouse gases, organic carbon, waste water are calculated on the LEAP (low emissions analysis platform) platform. We find that the carbon neutrality policy measures of the city of Seoul and the Republic of Korea are effective in reducing carbon emissions, and air pollutants and organic carbon are simultaneously mitigated from the carbon neutrality policy (co-benefits).