Valuing carbon saving potential of urban parks in thermal mitigation: Linking accumulative and accessibility perspectives

The greenhouse gas emissions and climate change are closely linked, as are climate change effects on public health. Urban parks are regarded as sustainable and affordable cooling intervention to climate warming, though carbon saving potential of urban parks in thermal mitigation are hard to value especially from accumulative and accessibility perspectives. This study valued both outdoor and indoor carbon saving potential of 65 urban parks in thermal mitigation using an accumulative outdoor carbon saving model based on park's surface temperature cooling curve and network analysis for spatial accessibility to parks cooling area in Greater Xi'an. We found that the carbon saving potential of urban parks could offset 3.6% of the metropolis' fossil fuel carbon emissions. The outdoor carbon saving was related to background climate, which was 734.3 t CO2/day in hot extremes, higher than normal summer days in 2019. The indoor carbon saving was 814.9 t CO2/day in hot extremes. To maximize the outdoor carbon saving potential, large ecological parks coupled with both blue and green infrastructures should be built in areas with sufficient land resources. And cooling networks are suggested with efficient small parks in densely populated areas. As all urban residents have higher requirements for thermal comfort in hot summers especially in hot extremes, the future park planning should be emphasized on both accumulative cooling effect and equitable accessibility. Though urban parks have substantial carbon saving potential, such potential is limited and only a decrease in CO2 emissions from fossil fuel burning would make the carbon neutrality goal achievable.