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This content will become publicly available on March 5, 2019

Title: Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth

Cities are concentrated areas of CO 2 emissions and have become the foci of policies for mitigation actions. However, atmospheric measurement networks suitable for evaluating urban emissions over time are scarce. Here we present a unique long-term (decadal) record of CO 2 mole fractions from five sites across Utah’s metropolitan Salt Lake Valley. We examine “excess” CO 2 above background conditions resulting from local emissions and meteorological conditions. We ascribe CO 2 trends to changes in emissions, since we did not find longterm trends in atmospheric mixing proxies. Three contrasting CO 2 trends emerged across urban types: negative trends at a residentialindustrial site, positive trends at a site surrounded by rapid suburban growth, and relatively constant CO 2 over time at multiple sites in the established, residential, and commercial urban core. Analysis of populationwithin the atmospheric footprints of the different sites reveals approximately equal increases in population influencing the observed CO 2, implying a nonlinear relationshipwith CO 2 emissions: Population growth in rural areas that experienced suburban development was associated with increasing emissions while population growth in the developed urban core was associated with stable emissions. Four state-of-the-art global-scale emission inventories also have a nonlinear relationship with population density acrossmore » the city; however, in contrast to our observations, they all have nearly constant emissions over time. Our results indicate that decadal scale changes in urban CO 2 emissions are detectable through monitoring networks and constitute a valuable approach to evaluate emission inventories and studies of urban carbon cycles.« less
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ; ORCiD logo [3] ;  [1] ;  [1] ;  [4] ;  [5] ;  [1]
  1. Univ. of Utah, Salt Lake City, UT (United States)
  2. Univ. of Washington, Seattle, WA (United States)
  3. National Center for Atmospheric Research, Boulder, CO (United States)
  4. Univ. of Utah, Salt Lake City, UT (United States); Univ. of Hawaii at Manoa, Honolulu, HI (United States)
  5. Arizona State Univ., Tempe, AZ (United States)
Publication Date:
Grant/Contract Number:
SC0010625; SC0010624; FG02-04ER63904; SC0005236
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 115; Journal Issue: 12; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Univ. of Utah, Salt Lake City, UT (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23). Climate and Environmental Sciences Division; USDOE
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1423734; OSTI ID: 1425455