A Latitudinal, Longitudinal, and Monthly Description of the Fossil-Fuel-Carbon-Dioxide Emissions for the Countries of the North American Carbon Program Andres RJ1, Boden TA 1, Gregg JS2, Losey L 3, Marland G 1 1Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6335 USA 2Department of Geography, University of Maryland, College Park, MD 20742 USA 3Department of Space Studies, University of North Dakota, Grand Forks, ND 58202-9008 USA email@example.com ABSTRACT A detailed, mechanistic understanding of the global carbon cycle needs description in multiple dimensions (e.g., fine spatial scales, fine temporal scales, accurate and precise mass fluxes, isotopic descriptions, etc.). Carbon dioxide emissions from fossil fuels are central to increased interest in the carbon cycle and are critical toward understanding other fluxes in the carbon cycle. This presentation describes a subset of recent efforts that have produced a description of fossil-fuel-derived, carbon dioxide emissions at finer spatial and temporal scales than previously available. This subset focuses on the countries of the North American Carbon Program: Canada, the United States, and Mexico. Emission fluxes will be characterized in both mass and stable carbon isotope space. Past analyses of the monthly time series, in both mass and stable carbon isotope space, for individual countries have shown significant differences in the month-to-month emissions. For example, for the United States mass time series for the years 1984 to 2003, 46% of the months are statistically different at the 2-sigma level from the 1/12 approximation (a typical default distribution pattern obtained by dividing annual emissions equally among the 12 months). Gregg et al. (submitted) have described North American emissions at monthly and state/province scales for the period 1990 to 2007. Monte Carlo simulations have now been used to extrapolate the extant data to years for which no data exist at the desired spatial and temporal scales. This has resulted in a time series for the years 1950 to the present. The Monte Carlo simulations have been conducted individually for gas, liquid and solid fuels. Emissions from gas flaring and cement manufacture are currently not included. These results, when combined with global carbon cycle models, should lead to a better understanding of the global carbon cycle. The work presented here is part of a larger effort which extended this type of analysis to 18 more countries around the world. Collectively, these 21 countries describe, explicitly, a majority of the total fossil- fuel-derived carbon dioxide emission flux. These 21 countries, via extrapolation, will be used to estimate the global fossil-fuel-derived carbon dioxide emission flux. 175000 Legend actual data Legend Sum of Three Fuels -26.0 NACP 150000 Solid Fuels mixed data World Liquid Fuels -27.0 125000 Gas Fuels Mass Emissions (Gg C) C (per mil) -28.0 100000 extrapolated data -29.0 75000 13 del -30.0 50000 -31.0 25000 -32.0 0 1950 1960 1970 1980 1990 2000 1950 1960 1970 1980 1990 2000 Year (monthly resolution) Year Graph 1 displays fossil fuel emission mass from the NACP countries for three fuels and their total Graph 3 displays the calculated stable carbon isotopic signature of the NACP-country monthly (the CDIAC flux categories of gas flaring and cement are not included in this graph as monthly data emissions shown in Graph 1 as well as the corresponding curve for the entire world (these curves also for these two categories are not fully available for the NACP countries). The emission lines are include emissions from gas flaring and cement not shown in Graph 1). The NACP countries average further delineated by different line colors to denote times when actual data exist and extrapolations 1.92 per mil lighter (become more negative) than the world, but the range of differences is –0.57 to from that data are used. Also delineated are times when a mix of actual and extrapolated data are –3.96 per mil. Both curves generally lighten with time because of the increasing use of natural gas in used (due to different data availability in the NACP countries). the fossil fuel mix. The annual range of signatures also generally increases with time. While yet to be fully explored, this 30 30 increased range reflects not only the changing mix of fossil fuels consumed with time, but also the 20 20 10 10 concentrated use of some fuels during specific seasons. 0 0 -10 o o -10 o 60 W 60 - 70 N -20 -20 30 J F M A M J J A S O N D 30 J F M A M J J A S O N D The average annual range for del 13 C signatures over a given year for the entire 1950 to 2005 NACP 20 20 10 10 data set is 1.92 per mil. The range in signatures spans 1.02 to 2.76 per mil. Corresponding average, 0 0 -10 o 55 N -10 o 70 W minimum, and maximum ranges for the world are 1.04, 0.46, and 1.35 per mil. -20 -20 J F M A M J J A S O N D J F M A M J J A S O N D 30 30 20 20 10 10 The curves are lightest during the northern hemisphere’s winter months and heaviest (less negative) 0 0 -10 o -10 o during the northern hemisphere’s summer months. This reflects the increased use of natural gas in Difference From Uniform Distribution (%) 50 N 80 W -20 -20 30 J F M A M J J A S O N D 30 J F M A M J J A S O N D the northern hemisphere during their winter. 20 20 10 10 0 0 -10 o 45 N -10 o 90 W -20 -20 J F M A M J J A S O N D J F M A M J J A S O N D 30 Legend 30 0.100 20 20 1/12 distribution 10 10 Average of 56 Monte Carlo Simulations 0 0 0.095 -10 o -10 100 o W 40 N Monthly Fraction -20 -20 J F M A M J J A S O N D J F M A M J J A S O N D 30 30 0.090 20 20 10 10 0 0 0.085 -10 o -10 110 o W 35 N -20 -20 J F M A M J J A S O N D J F M A M J J A S O N D 0.080 30 30 20 20 10 10 0.075 0 0 -10 o -10 120 o W Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 30 N -20 -20 J F M A M J J A S O N D J F M A M J J A S O N D Month 30 30 20 20 Graph 4 displays 12 of 56 runs of the Monte Carlo simulation, the 1/12 flat distribution, and the 10 10 0 0 average of those 56 runs. These 12 runs were chosen as they displayed minima or maxima in -10 o 20 - 25 o N -10 130 o - 160 o W -20 J F M A M J J A S O N D -20 J F M A M J J A S O N D particular months for the NACP countries. The data show a statistically significant variation from a Month Month 1/12 assumed annual distribution (equal to 0.083). The pink symbols on the average line span Graph 2 displays the latitudinal and longitudinal mean monthly distributions of the total fossil fuel approximately one standard deviation. Average data for nine of the 12 months lie outside plus or emissions shown in Graph 1. The difference from a uniform distribution (equal to 1/12 of the annual minus one standard deviation from an assumed 1/12 distribution. This decreases to six of 12 months total in each month) is shown, given in percent. The data are shown for years 1990 to 2007 only. being statistically different from a 1/12 distribution at plus or minus three standard deviations. Tabular data are spread spatially by the geographic centroid of the smallest political unit (e.g., province in Canada, state in the U.S., and country in Mexico). The data have been converted into monthly fractions for ease of interpretation.
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