Linking neighborhood canopy coverage to city-scale biogenic CO2 uptake in Paris, France

Le résumé fourni par la source

Cities are major sources of anthropogenic carbon dioxide (CO2) emissions. Reducing these emissions is not enough to make urban areas carbon neutral without biogenic sinks offsetting a portion of the remaining emissions. Urban vegetation provides a CO2 sink that contributes to the net CO2 balance of a city. CO2 uptake of a neighborhood is strongly dependent on the number of trees, i.e. the canopy coverage. The current EU Nature Restoration Law recommends that each city should have a canopy coverage of 30% to get the multiple benefits of urban vegetation. However, this limit value is rarely reached at a neighborhood level, where most of the benefits take place. In this study, we utilized urban land surface model SUEWS (the Surface Urban Energy and Water balance Scheme) in greater Paris area, France, to examine the variability of biogenic CO2 fluxes across the city with different canopy coverages. SUEWS simulates joint energy, water, and CO2 exchanges on local neighborhood scale with meteorological forcing and vegetation-specific parameterizations. The study period was from March 2024 to June 2025, corresponding to the availability of eddy covariance (EC) measurements from an urban forest Vincennes located in eastern Paris, which were used to evaluate the model. The meteorological input was from ERA5 data. First, we tested the effect of choosing different sets of biogenic CO2 parameters (Park trees, street trees, forest) for modelling CO2 and heat fluxes. We then upscaled the results by modelling CO2 in the greater Paris area with a 500 m x 500 m resolution. Results of CO2 uptake were also compared to canopy coverage of the grids to see the effect of urban vegetation offsetting the CO2 emissions on a neighborhood scale.

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