Remote sensing-based frameworks to quantify city-level carbon fluxes in urban green infrastructures

The urban population is experiencing rapid growth, and it is estimated that around 90% of people will be living in cities by the year 2100. Given that urban areas are significant sources of greenhouse gas and pollutant emissions, and with the expectation that these urban areas will become even more densely populated, achieving sustainable urban living requires careful and well-informed urban planning for infrastructures capable of effectively mitigating these emissions. One commonly proposed approach to address this challenge is the implementation of urban green infrastructures, which are often regarded as net sinks for CO₂. However, due to the diverse and varied land use within urban areas, our ability to precisely isolate and quantify their overall impact on the city's carbon balance is limited.

Our research aims to overcome this limitation by testing two distinct frameworks. The first integrates remote observations with local measurements to determine the carbon balance of green infrastructures at the city level, ultimately producing a detailed CO₂ sequestration map of these infrastructures. The second utilizes satellite observations of solar-induced chlorophyll fluorescence, a signal emitted exclusively by vegetation, to estimate urban vegetation's city-wide carbon sequestration potential. Our findings demonstrate that these two frameworks provide valuable insights into the carbon sequestration capacity of green infrastructures.

The frameworks developed in this study offer a significant advancement in understanding the contribution of green infrastructures to the carbon budget of cities. This improved understanding can inform the planning of low carbon-emitting cities and aid in identifying green areas with limited—or even negative—net carbon uptake. Additionally, the results of this research may be instrumental for policymakers and city planners in developing more sustainable urban environments.