This week the U.S. Environmental Protection Agency (EPA) announced the release of the annual U.S. greenhouse gas inventory. Overall the report shows US emissions of greenhouse gases increased by 3.2% in 2010 from 2009, but are still 3% below 2008 levels. Total gross US emissions of the six main greenhouse gases in 2010 were equivalent to 6,822 million metric tons of carbon dioxide equivalent and according to the EPA represents 18% of world CO2 equivalent emissions based on the InternationalEnergy Agency, IEA, estimates. Net (of the CO2 sinks of our forest land) US emissions of CO2 are reported to be 5,747 million metric tons down 4% since 2008. It is interesting to note that while worldwide CO2 emissions and US CO2 emissions were both down in 2009 from 2008 levels, worldwide CO2 emissions increased 5% from 2008 levels while US CO2 emissions are still 4% below 2008 levels. In the past 20 years, the US is estimated to have increased CO2 equivalent emissions by 10% as our share of worldwide emissions has fallen. The peak of CO2 emissions in the US was 2007.
Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride. The US collects data and estimates CO2 equivalent emission because in 1992, the United States signed and ratified the United Nations Framework Convention on Climate Change, UNFCCC. The UNFCCC dictates the methodology to calculate and track greenhouse gasses looking only at CO2, CH4 and N2O. Stratospheric ozone depleting substances, CFCs, HCFCs, and halons are not required to be included in national greenhouse gas emission inventories, they are tracked under another treaty.
Naturally occurring greenhouse gases include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Several classes of halogenated substances that contain fluorine, chlorine, or bromine are also greenhouse gases, but they are, for the most part, solely a product of industrial activities. Although the direct greenhouse gases CO2, CH4, and N2O occur naturally in the atmosphere human populations have changed their atmospheric concentrations by burning fossil fuel, removing forest cover, breathing, raising animals. It is reported by the IEA that concentrations of these greenhouse gases have increased globally by 39%, 158%, and 19%, respectively since 1750.
TheInventory of U.S.Greenhouse Gas Emissions and Sinks: 1990-2010 is the latest annual report that the United States has submitted to the UNFCCC, as it tries to orchestrate intergovernmental efforts to control greenhouse gas emissions. EPA prepares the annual report in collaboration with experts from multiple federal agencies and now with the data from the EPA’s Greenhouse Gas Reporting Program launched in October 2009, requiring the reporting of carbon dioxide data from large stationary emission sources, as well as suppliers of fuel that would emit greenhouse gases if used, the US estimates of greenhouse gases should be more accurate. Of the greenhouse gasses generated in the US 33% is from the generation of electricity and 26% is from transportation.
The EPA and the Department of Transportation’s NationalHighway Traffic Safety Administration (NHTSA) new millage and emissionstandards for automobiles and light trucks for model year 2012 through 2016 require these vehicles to meet an estimated combined average emissions level of 250 grams of carbon dioxide (CO2) per mile in model year 2016, equivalent to 35.5 miles per gallon (mpg) if the automotive industry were to meet this CO2 level all through fuel economy improvements. In March the EPA announced the Carbon PollutionStandard for NewPower Plants that limits the amount of CO2 that can be produced for each megawatt of electricity produced. That standard effectively changes the fuel of choice for all future power capacity additions to natural gas, nuclear, or the renewable category (with government subsidies). All existing plants and currently permitted and built in the next 12 months will be grandfathered and exempt from this new rule for a period of time. Reductions in CO2 generation from power plants will not improve human health. CO2 is vital for photosynthesis and the environment and has no direct negative human health effects. Humans produce CO2 and exhale it so it is present at levels much exceeding atmospheric concentrations in the lungs.
In the past year EPA has issued two other regulations targeted at coal fired power plants, EPA’s Cross-State Air Pollution Rule, CSAPR, and Mercury and Air Toxic's Standard, MATS. CSAPR which requires reductions of sulfur-dioxide and nitrogen-oxide emissions in coal fired plants was made final in July but at the end of last year,the U.S. Court of Appeals District of Columbia Circuit granted a stay to the implementation of the CSAPR pending resolution of the legal challenges. MATSregulates mercury, arsenic, acid gas, nickel, selenium, and cyanide and was finalized on December 21. 2011. Both of these regulations are anticipate to have direct human health benefits. Nonetheless, appears that CO2 and to a lesser extent the other greenhouse gases are the EPA’s primary focus. However as can be seen above, US CO2 emissions is growing slowly if at all and accuracy in data collection, and increased US regulation of CO2 emissions from power plants and automobile millage standards is not going to slow world CO2 emissions growth.