High-resolution carbon neutrality mapping and a heterogeneity analysis for China?s two typical megalopolises

High-resolution carbon neutrality mapping is critical to guide carbon sequestration increase and carbon emissions reduction in spatial. Based on multiple sources of big data, which include both high-precision satellite data and field data, this study explored a new approach to simulate the spatial distribution of carbon neutrality and comprehensively compared the influencing factors of industry structure, land use and landscape for Beijing and Shanghai. The results indicate that carbon emissions in Shanghai are 1.8 times those of Beijing. Carbon sink in Beijing can only offset about 13% of carbon emissions, while Shanghai shows little carbon sink due to limited natural green land. Large areas in the west, north and northwest of Beijing show carbon sink, and high carbon emission values are mainly located in the southeast of the urban area. Shanghai shows a more intensive carbon emissions distribution, and the carbon emissions are widely distributed, covering the whole area except for Chongming island. Carbon emissions in urban regions generally show a decreasing trend from urban centre to suburb. Shanghai has much higher carbon neutrality pressure than Beijing, one reason for this is that Shanghai has very limited natural green land, and another reason is that Shanghai has many more industries, which generate a large amount of carbon emissions, and this amount is still increasing, although industry carbon emissions have obviously decreased since 2000. Landscape can influence carbon emissions but not as strongly as industry and land use structure. The landscape compactness of water, wetland and industry land in Shanghai is higher than Beijing, whereas all the other lands in Beijing are more compact. Finally, some policy implications are proposed for the two cities.