Health co-benefits of achieving sustainable net-zero greenhouse gas emissions in California

The achievement of net-zero greenhouse gas (GHG) emissions by 2100 is required to limit global temperature rise below 2 degrees C above preindustrial levels. Earlier accomplishments of net-zero GHG emissions in developed regions support this global target. Here, we develop a road map for California to achieve net-zero GHG emissions sustainably in 2050 by using detailed modelling of energy system transformation, cross-sectoral connectivity and technology penetration, as well as quantify the associated health co-benefits from reduced co-emitted air pollutants. We find that approximately 14,000 premature deaths can be avoided in California in 2050 and that these health co-benefits are disproportionately higher in disadvantaged communities (that is, 35% of avoided deaths will come from 25% of the state's population). The annualized monetary benefits (US$215 billion) exceed the GHG abatement cost (US$106 billion) by US$109 billion. This road map requires the use of bioenergy with carbon capture and sequestration technology to offset some GHG emissions. However, this technology comes at a price as it would emit a considerable amount of air pollutants and reduce health co-benefits by US$4 billion. Nevertheless, our analysis shows that ambitious GHG reduction efforts can provide substantial health co-benefits, especially for residents of disadvantaged communities. Transforming the energy system to achieve net-zero carbon emissions by 2100 is vital to fight climate change. This target can be achieved in California, USA, by 2050-alongside air quality benefits especially in disadvantaged communities-by using bioenergy with carbon capture and sequestration.