Human population impact on the atmospheric CO2 levels of NYC over the last 180 years: Results from an urban to rural transect

Background/Question/Methods

Precise records of global atmospheric CO₂ concentrations are one of the most widely recognized and important data sets documenting anthropogenic influences on the atmosphere and potential climate forcing.  It is generally acknowledged that there is an increasing need for quantifying the same CO₂ record at smaller spatial scales, particularly those associated with large metropolitan urban areas where populations may have a significant impact on local conditions and ecosystem services.  While many recent monitoring networks have been established, few records of direct human contributions to local levels of atmospheric CO₂ extend beyond a few years.  We show a 150-year record of fossil fuel CO₂ levels determined from tree ring ¹⁴C in New York City (NYC) and the surrounding rural areas. 

Results/Conclusions

The historically dense urban population has had a limited influence on the local atmospheric CO₂ relative to both rural and mean global background levels.  The largest anthropogenic signal detected over the entire 180 year record is 16 ± 1.3 ppm CO₂ above the global mean (during the growing season).  Furthermore, the CO₂ emissions per capita have been decreasing since the 1950’s.  With increasing attention being given to national emissions monitoring, establishing historical patterns of local atmospheric CO₂ levels can provide important data for large urban areas such as NYC.