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Harvard Forest Symposium Abstract 2005
- Title: A Harvard Forest Perspective: Are EPA U.S. emissions of the greenhouse gases correct?
- Primary Author: James Elkins (University of Colorado and NOAA/CMDL)
- Additional Authors: Geoffrey Dutton (University of Colorado and NOAA/CMDL); Elaine Gottlieb (Harvard University); Michael McElroy (Harvard University); Steven Wofsy (Harvard University)
- Abstract:
Every country is requested to make emissions of all greenhouse gases available to the United Nations Environmental Program (UNEP). This information will be useful in examining compliance with the reductions in emissions mandated by the Kyoto Protocol. While not a signatory nation on the Kyoto Protocol, the United States does provide inventory emission estimates. These estimates are based on a number of sources including estimates from the U.S. Environment Protection Agency (EPA), observations, and industrial emissions. The U.S. EPA uses a vintaging model to estimate emissions of many of the greenhouse gases. This model calculates emissions of the greenhouse gas by using mean lifetime of the equipment (car, refrigerator, etc.), production values for the fuel or feedstock, maintenance leakage during replacement (if any), recovery methods, and improved efficiency with new models after replacements. The problem is that the emissions calculated by vintaging model changed from 2003 to 2004 EPA reports without an explanation.
Air originating from the southwest region of the NIGEC Harvard Forest site receives air predominately from the metropolitan corridor of New York City and Washington D.C. There are continuous measurements of carbon dioxide (CO2), carbon monoxide (CO), sulfur hexafluoride (SF6), nitrous oxide (N2O), and selected halocarbons. As an additional check on the measurements, there are 1-2 times month collections of flask samples for analysis by University of Colorado employees working with NOAA scientists in Boulder, Colorado. During pollution events from the southwestern sector, concentrations of carbon monoxide are correlated with increased levels of sulfur hexafluoride and other non-CO2 greenhouse gases. The U.S. EPA reports CO emissions using fossil fuel emissions and vintaging model for additional sources. Using wintertime observations, CO and CO2 are correlated during pollution events. Since there is snow cover and little biological production and removal of CO2, it is possible to use the CO2: CO correlation slope to estimate a yearly contribution of CO2 emissions from fossil fuel emissions. The agreement between Harvard Forest observed emissions and U.S. EPA calculated emissions are reasonable. In a similar approach, CO correlations with the non-CO2 greenhouse gases are used to calculate emissions. There are considerable disagreements with observed and U.S. E.P.A. calculated emissions for the non-CO2 greenhouse gases. Observed emissions from Harvard Forest appear to be representative of the U.S. as a whole when compared to other tower stations (Wisconsin and North Carolina) and a 2003 North American airborne campaign. Sites like Harvard Forest offer the potential to validate greenhouse gas emissions. This validation technique will be extremely useful to policy makers who must decide how to deal with future emissions of greenhouse gases and the international consequences of those emissions to the Earth’s atmosphere.
- Research Category:
