INCREASING THE TEMPORAL AND SPATIAL RESOLUTION OF FOSSIL-FUEL CARBON EMISSIONS ESTIMATES FOR THE UNITED STATES OF AMERICA T. J. Blasing Oak Ridge National Laboratory Christine Broniak, Oregon State University Gregg Marland, Oak Ridge National Laboratory Sponsor: U.S. Department of Energy, Office of Science, Biological & Environmental Research

Improved temporal and spatial resolution of fossil-fuel carbon emissions to the atmosphere (as CO 2 ) can improve the accuracy of carbon-cycle models. Temporal resolution to accommodate annual (and daily) cycles in photosynthetic activity Spatial resolution to capture atmospheric CO 2 gradients downwind of large source areas (e.g., large cities and coal-fired power plants)

Previously, atmospheric emissions of fossil-fuel carbon had only been given on an annual basis. USA totals from Marland, Boden & Andres on CDIAC website Finer scales not available for some countries Useful for comparing countries & tracking national emissions trends Updated through 2002

By 2009 meeting (for USA): Temporal resolution will capture the daily cycle Spatial resolution will capture CO 2 gradients around large sources (e.g. cities, coal-fired power plants) Data assimilation results need to be aggregated and checked against emissions estimated directly from fossil- fuel consumption. For the USA, (~ 23% of global fossil fuel carbon emissions) we have increased the spatial and temporal resolution of fossil-fuel based emissions estimates.

Monthly values: Annual range ~ 20% of annual mean Shape of annual pattern is changing.

Shape of annual pattern is changing Since early 1980’s, annual range has shrunk by 4Tg August-May difference had increased by 5 Tg Population projections suggest these trends will continue

Monthly estimates of δ 13 C in fossil-fuel carbon emissions were also calculated

13 C concentrations in atmospheric CO 2 are declining as the fossil-fuel fraction increases. Mauna Loa data from Keeling, Bollenbacher and Whorf.

State-by-state per capita emissions (Mg/person) show effects of socio- political-economic factors CaliforniaNew Mexico

Per capita carbon emissions by State (Mg/person) (Year 2000) Apportioning national value by population is inaccurate, Coal rich states with low populations show highest value, National plan is needed for carbon reductions, Spatial diversity has increased over time.

Spatial variance of per-capita carbon emissions has increased

Finer temporal/spatial breakdown of fossil-fuel carbon- emissions can improve accuracy of C-cycle models. Ultrafine scale emissions estimates based on data assimilation procedures should be aggregated and checked with “ground truth” estimates obtained from fossil-fuel consumption data. Greater resolution provides insights about dynamics and trends. The spatial breakdown of the data poses a challenge for trying to use per capita emissions as a measure of equity or to provide mitigation targets.