To the Editor:
Hafemeister and Schwartz state (Phys. Society, 37, 3, p. 3, July 2008) state that carbon released worldwide from burning carbon and deforestation has recently been about 7.1 Gt/yr. No source is cited. The total coal production in the United States in 2003 has been 0.970 Gt (Encyclopedia of Energy Engineering, Energy Information Administration, 2006). In 2002 the United States consumed 1.02 Gt of petroleum. As carbon constitutes 84 percent of the weight of petroleum 0.860 Gt of carbon is burned when all the above petroleum is consumed. Thus, the United States can be responsible for not more than 1.83 Gt of the worldwide 7.1 Gt or 25% of the carbon cited by the authors.
Unfortunately it cannot be established where the carbon dioxide in the atmosphere is coming from and this leaves the field wide open for speculations a la Hafemeister and Schwartz.
The question arises whether destroying the United States economy would have a significant effect on the global warming trend.
Hafemeister & Schwartz respond:
Vladislav Bevc’s “question” implies the incorrect idea that improving US energy use would come at the expense of the economy. In fact, the transition to energy efficiency and renewable energy is necessary for long-term economic health. Our present difficult economic state provides great opportunity for this needed transition in order to prevent increased energy dependence (often on countries we are not friendly with) and the associated foreign debt, higher energy costs, and environmental destruction. The question as we see it is this: “Given that we are presently planning to financially assist private companies to rescue the economy, are we going to build infrastructure in a direction that will benefit us and our children, or continue to support the wasteful, inefficient technologies and institutions that are partially responsible for the present crises?”
Vladislav Bevc’s challenge implies he is not convinced that the observed increase in CO2 is due to burning fossil fuels. We direct you to the IPCC Fourth Assessment Report: The Physical Science Basis, page 138-139. Most or all the CO2 increase is from burning of fossil fuels as supported by atmospheric carbon isotope measurements. So, contrary to Vladislav Bevc’s claims, it can be established where the CO2 in the atmosphere is coming from, and in fact it is from the burning of fossil fuels.
The 2008 APS study, “Energy Future: Think Efficiently” gives many examples on cost effective actions to increase enduse efficiently. Figure 2 of the APS report displays mitigation measures that can reduce 3.0 Gtons/yr of carbon dioxide per year (0.8 Gtons/yr of carbon) for no net cost. Figure 3 of the APS report compares per capita income in California and the US with the results of strict energy conservation in California. From 1975 to 2005, per capita income rose from $7,000 to $37,000 in the U.S., while in California it rose from $3,000 to $44,000. US per capita electrical consumption rose from 8,400 to 12,000 kWh/yr while in California the use of electricity remained approximately constant at 7,800 kWh/ yr. While US per capita electrical use rose by 30% (and remained flat in California), California incomes rose more than average US incomes. Other factors are also involved, but saving energy didn’t seem to hurt per capita income.
We agree with Bevc that the US produces about 25% of the annual global carbon dioxide rate. The data we used in the article and this note comes from the US Energy Information Administration. Recent EIA data: Petroleum (2007, Mbbl/day): US/Earth = 20.7/85.9 = 24.1%, Natural gas (2006, TCF/yr): US/Earth = 23.1/104.4 = 22.1%, Coal (2007, Gtons/yr): US/Earth = 1.1/7.2 = 15.2%.
David Hafemeister and Pete Schwartz
Cal Poly University,
San Luis Obispo, CA
This contribution has not been peer refereed. It represents solely the view(s) of the author(s) and not necessarily the views of APS.