Print PageCarbon Dioxide is a well mixed greenhouse gas, but how, where, and when it is exchanged with Earth’s surface is an incredibly complex spatio-temporal, coupled natural-human problem. Nowhere is this challenge more pronounced than in the urban environment. Fixed objects like buildings and trees, and mobile elements like cars and people, exchange carbon across a wide range of spatial and temporal scales with a dynamic set of driving variables. These exchanges are highly synergistic rather than simply additive, and involve human behavior and socio-economics as much as biophysical mechanism, making a coupled natural-human perspective essential for both quantifying and understanding urban carbon exchange. Most research to date has focused on urban carbon emissions, or separately on carbon exchange in rural, forested environments. Thus, we are currently lacking empirical data on carbon cycling across urban to rural gradients that are critical for effectively reducing emissions and advancing urban sustainability efforts. Using the Boston, MA region as a case study, we explore the spatial and temporal patterns in anthropogenic emissions and atmospheric concentrations across an urban to rural gradient. Micrometeorological, biometric, econometric, and remote sensing methods are combined to characterize these relationships and determinants.
Results/Conclusions
We find that concentrations of CO2 within Boston’s urban core are 12.7 ± 1.4 ppm greater that concurrent measurements at the rural Harvard Forest study area (~92 km away). Weekday concentrations are 2.1 ppm greater than weekend concentrations, with an 11.1 ppm and 5.1 ppm amplitude in the diurnal cycle on weekdays and weekends, respectively. Careful fusion of emissions estimates with direct atmospheric observations are a critical component for developing robust carbon validation methods.
