FIGURE 4.3 Global emissions of HFC-134a from several inverse atmospheric models, compared with UNFCCC reported Annex I emissions and the European Commission’s Emission Database for Global Atmospheric Research (EDGAR), for 1990-2002. Most production facilities and emissions for HFC-134a are in Annex I countries. SOURCE: Courtesy of Michael Prather, University of California, Irvine. Modified from Prather et al. (2009). Copyright 2009 American Geophysical Union. Reproduced by permission of the American Geophysical Union.

FIGURE 4.3 Global emissions of HFC-134a from several inverse atmospheric models, compared with UNFCCC reported Annex I emissions and the European Commission’s Emission Database for Global Atmospheric Research (EDGAR), for 1990-2002. Most production facilities and emissions for HFC-134a are in Annex I countries. SOURCE: Courtesy of Michael Prather, University of Cali-fornia, Irvine. Modified from Prather et al. (2009). Copyright 2009 American Geophysical Union. Reproduced by permission of the American Geophysical Union.

spheric inverse modeling can provide a strict test of the global sum of national greenhouse gas emissions inventories on an annual basis, but it has not been able to identify the countries whose emissions are in error.

NEW APPROACHES FOR INCREASING THE ACCURACY OF NATIONAL EMISSIONS ESTIMATES

Because of the twin problems of transport error and the separation of natural from anthropogenic fluxes, the uncertainty in tracer-transport inversion estimates of anthropogenic emissions for continents and nations can be as large as 100 percent (Table 4.1). These errors currently make tracer-transport inversion impractical for monitoring national emissions. Research is improving the representation of transport and biogeochemistry in models, but at the slow pace at which new observations are becoming available, advances cannot be expected to deliver the required accuracy during the coming decade. The following approaches, which would augment current research, would shift the observing paradigm for the carbon cycle and substantially improve our capability to monitor national emissions in the near term.

Measurements of Large Emission Sources

A large fraction of fossil-fuel emissions emanates from large local sources, such as cities or power plants, and thus the effect of national mitigation measures should be evident in the “domes” of CO2 that they produce (Idso et al., 2001; Pataki et al., 2003; Rigby et al., 2008a). For example, more than 57 percent of U.S. fossil-fuel emissions occur in areas that have a flux rate that exceeds 2 kg C m–2 yr–1, which corresponds to ~1.7 percent of the total surface area (including power plants, cities, and other point sources; Table 4.2). Cities also

TABLE 4.2 U.S. Fossil-Fuel Emissions as a Function of Carbon Density at 0.1 Degree Grid Spacing

Carbon Density of Emissions (kg C m–2yr–1)

Area (%)

Percentage of Total U.S. CO2Emissions

≤2

98.3

42.7

2-4

0.9

13.6

4-10

0.6

18.0

10-20

0.2

15.1

20-max

0.1

10.7

SOURCE: VULCAN emissions inventory; <www.purdue.edu/eas/carbon/vulcan>.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement