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To learn more about a CarbonTracker component, click on one of the above images.
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1. Introduction
Human beings first influenced the carbon cycle through land-use change. Early humans used fire to control animals and later cleared forest for agriculture. Over the last two centuries, following the industrial and technical revolutions and the world population increase, fossil fuel combustion has become the largest anthropogenic source of CO2. Coal, oil and natural gas combustion indeed are the most common energy sources in both developed and developing countries. Various sectors of the economy rely on fossil fuel combustion: power generation, transportation, residential/commercial building heating, and industrial processes. In 2004, the world emissions of CO2 from fossil fuel burning, cement manufacturing, and flaring reached 7.9 PgC (one PgC=1015 grams of carbon) [CDIAC] and we estimate the global total for 2006 to be 8.4 PgC. This represents a 36% increase over 1990. The North American (U.S.A, Canada, and Mexico) flux of CO2 to the atmosphere from fossil fuel burning was 1.9 PgC in 2004, representing 23% of the global total. The International Energy Outlook has projected that the global total source will reach 9.2 PgC in 2015 and 11.9 PgC in 2030 [DOE]. Recently, however, fossil fuel emissions have accelerated significantly, and we are now on track to exceed this 2015 projection sometime in 2008.
2. Detailed Description
The fossil fuel emission inventory used in CarbonTracker is derived from independent global total and spatially-resolved inventories. Annual global total fossil fuel CO2 emissions are from the Carbon Dioxide Information and Analysis Center (CDIAC) [Marland et al. 2006] which extend through 2004. Fluxes are then spatially distributed in two steps: First, we use the country totals from Marland et al. [2006] for the coarse scale flux distribution, and then we distribute the country totals within the countries according to the spatial patterns from the EDGAR inventories [EDGAR, Olivier and Berdowski, 2001]. In order to extrapolate these fluxes to 2005 and 2006, we derive relative increases for each fuel type (solid, liquid and gas) and for each country from the BP Statistical Review of World Energy for 2005 and 2006. The CDIAC country-by-country totals, however, do not sum to the CDIAC global total. We hold the global totals to be more accurate and ascribe the difference (about 0.3 PgC/yr) to marine bunker fuels. Emissions from these bunker fuels are placed entirely in the ocean basins along shipping routes according to patterns from the EDGAR database. Finally, a seasonal cycle based on the Blasing et al. [2005] analysis for the United States, which has ~20% higher emissions in winter than in summer, is imposed on the North American emissions between 30 and 60 degrees north; at the present time, no seasonality is imposed on emissions outside North America. The uncertainty attached to the total source is of the order of 15%. This source is not optimized in the current CarbonTracker system as we do not believe our current network can constrain this source separately from the others. Although the contribution of CO2 from fossil fuel burning to the observed CO2 mole fraction is considered known, extra model error is included in the system to represent the random errors in fossil fuels.
3. Further Reading
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