Fertility-rate recovery and double-income policies require solving the carbon gap under the Paris Agreement

In 2015, in response to the Paris Agreement for mitigating an increase in global temperatures, the Japanese government committed itself to reducing greenhouse gas (GHG) emissions by 26% below 2013 levels by 2030. In the same year, the government also committed itself to overcoming the barriers to economic growth imposed by an aging society with a low birthrate by implementing socio-economic policies referred to as “A Society in Which All Citizens are Dynamically Engaged”. Regarding achievement of these two national targets, this study examines the extent to which increases in the total fertility rate and the number of double-income households would impact the domestic carbon footprint (CF) associated with household consumption in 2030. The findings show that the total household CF in 2030 would range from 683 to 815 Mt-CO₂eq/y, depending on the consumer preferences resulting from implementation of the socio-economic policies. This implies that, compared with a business-as-usual scenario, the GHG emissions associated with household consumption would need to be reduced by more 7.8–29% in order to meet the CF target that can be set using the CF for 2009 and the reduction target proposed in the Paris Agreement. Furthermore, the household CF for non-energy commodities would need to be reduced by 17–28% in order to satisfy the trade-off between the socio-economic policies and the emissions mitigation target for 2030, even if the current CO₂ emissions targets for household energy use and private car use are achieved.