by Max Schulz



Manhattan Institute/Zogby Survey of Adults Question Frequencies

Manhattan Institute/Zogby Survey of Adults Question X-tabs





The premise of anthropogenic (man-made) global warming theory is that greenhouse-gas emissions from human activities—namely, the burning of fossil fuels that release carbon dioxide—are rapidly accelerating the warming of the Earth, as projected by computer models. An authoritative source for the theory is the IPCC, whose most recent climate assessment states: “Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic [greenhouse gas] concentrations.”[125] To those who subscribe to anthropogenic global warming theory, reducing man-made carbon-dioxide emissions is the top priority in the struggle to save the Earth from potentially catastrophic changes in climate caused by a change in the composition of the atmosphere.

Carbon dioxide, one of a number of heat-trapping greenhouse gases,[126] is emitted both naturally and by human activities, such as coal-fired power production.[127] The EIA reports that carbon-dioxide emissions from the burning of petroleum, coal, and natural gas constituted 82 percent of all U.S. man-made greenhouse-gas emissions in 2006.[128] According to the IPCC, between 1970 and 2004, total greenhouse-gas emissions increased 70 percent worldwide, while carbon-dioxide emissions rose 80 percent.[129] As of 2008, thirty-nine out of every 100,000 particles of the atmosphere were carbon dioxide, a figure 40–45 percent higher than before the start of the Industrial Revolution.[130]

Without question, then, industrialization has increased carbon-dioxide emissions—but are human emissions significant enough to accelerate warming? Have they already done so? Both the Earth’s average temperature and global carbon-dioxide emissions increased during the twentieth century. But what should we make of research showing recent warming on Mars and Pluto, planets without power plants or automobiles? Is planetary warming simply a natural phenomenon? A better understanding of the issues surrounding these and similar questions is needed, if policymakers intend to craft prudent energy policies.

According to David J. C. MacKay, the burning of fossil fuels sends seven gigatons (3.27 percent) of carbon dioxide into the atmosphere each year, while the biosphere and oceans account for 440 (55.28 percent) and 330 (41.46 percent) gigatons, respectively... “Burning fossil fuels, in contrast,” writes MacKay, “creates a new flow of carbon that, though small, is not cancelled.”

Central to climate-change discussions is an examination of just how much atmospheric carbon dioxide is attributable to human activities, rather than to nature. Sixty-three percent of survey respondents believed that human activity, such as the burning of fossil fuels, is the greatest source of carbon-dioxide emissions. While some estimate that the human share of atmospheric carbon dioxide is as small as 3 percent—according to David J. C. MacKay, professor of natural philosophy in the Department of Physics at the University of Cambridge, the burning of fossil fuels sends seven gigatons (3.27 percent) of carbon dioxide into the atmosphere each year, while the biosphere and oceans account for 440 (55.28 percent) and 330 (41.46 percent) gigatons, respectively[131]—total human emissions have jumped sharply since the Industrial Revolution; and it is this added atmospheric carbon that worries many. MacKay writes that, yes, carbon is emitted naturally into the atmosphere but that the atmosphere also sends carbon back to the land and oceans and that these carbon flows have canceled each other out for millennia. “Burning fossil fuels, in contrast,” writes MacKay, “creates a new flow of carbon that, though small, is not cancelled.”

Though the amount of additional carbon from human activities is dwarfed by natural carbon levels, might the added carbon increase from humans be enough to alter climate dynamics? Are humans to blame for global warming? If so, what portion of the warming do we cause? Advancing the climate debate depends on a clear understanding of emissions’ impacts.

Though a causal link between human carbon-dioxide emissions and accelerated warming has not been proved, national policymakers broadly support curbing carbon emissions via government regulation. One way to lower emissions is to reduce or eliminate the burning of carbon-based fuels, such as coal or natural gas. Another option is to replace motor vehicles that run on petroleum-based fuels with lower- or non-carbon-emitting vehicles, such as electric cars. However, because the overwhelming majority of our energy is derived from fossil fuels, such carbon-reduction strategies are easier planned than implemented.

As an alternative—or at least until we find ways to displace fossil fuels and conventional vehicles—financial instruments known as carbon offsets are used to cancel out carbon emissions. Each carbon offset represents the reduction of one metric ton of carbon dioxide through carbon-reducing activities like tree planting or renewable energy production. The idea is to purchase enough carbon offsets to reduce or cancel out one’s total carbon-dioxide contribution. A plurality (45.6 percent) of respondents believed that carbon offsets are an easy way to cancel out one’s carbon-dioxide emissions. Once again, however, this is easier said than done.[132] In fact, some carbon offsets represent activities that would have been carried out in any case. As a result, the United States Federal Trade Commission is investigating the legitimacy of the carbon-offsets business,133 and carbon offsets have come under fire in Europe as well.[134]

Particularly among industrialized nations, the U.S. is castigated for not ratifying the Kyoto Protocol, an international agreement to reduce greenhouse-gas emissions. However, several large carbon emitters—namely China, India, and other “developing” countries—did ratify the protocol but are exempted from its costly carbon-reduction mandates.[135] (According to Danish political scientist Bjørn Lomborg, the annual cost of the Kyoto Protocol is $180 billion.)[136] Considering the current and projected future emissions of these nations, their exemption from the mandates is enormously significant.
According to the EIA, collective carbon-dioxide emissions from China and India are projected to account for 34 percent of total world emissions in 2030, with China alone accounting for 28 percent of the world total.[137] The EIA[138] and the Netherlands Environmental Assessment Agency[139] report that China’s carbon-dioxide emissions from burning fossil fuels surpassed those of the U.S. in 2006, and the EIA projects China’s energy-related carbon-dioxide emissions to exceed U.S. emissions by almost 15 percent in 2010 and by 75 percent in 2030.[140] Given these estimates, many Americans oppose agreeing to costly carbon-reduction plans while China, India, and other nations are not similarly bound.

Over 46 percent of respondents believed that reducing carbon emissions will be simple and inexpensive, while a plurality (48.6 percent) disagreed. Regardless of the means chosen to reduce carbon-dioxide emissions, the task will be complex and expensive.[141] Carbon taxes can conceivably lead to higher costs on everyone—from corporations to individuals—since everyone is responsible for at least some of the carbon dioxide that enters the atmosphere. Likewise, cap-and-trade systems and other carbon-reduction plans will make energy more expensive, increasing expenses for producers and raising costs for consumers.

The U.S. Senate struck down the most well-known cap-and-trade proposal to date, the Lieberman-Warner bill,[142] largely because of its projected costs.[143] The bill called for reductions in greenhouse-gas emissions of 15 percent below 2005 levels by 2020, 30 percent below 2005 levels by 2030, and 70 percent below 2005 levels by 2050. One study estimated that reductions of this magnitude would, by 2030, reduce GDP by up to $669 billion per year, cost households an average of up to $6,752 per year, increase gasoline prices up to 144 percent, increase electricity prices up to 129 percent, increase natural gas prices up to 146 percent, and eliminate up to 4 million jobs.[144] President Obama’s plan is to require a reduction in greenhouse gases of approximately 83 percent below 2005 levels by 2030.[145]

Fundamentally transforming the U.S. economy, which is firmly rooted in fossil-fuel-based energy, is a daunting task. Whether we should do so is an important question. Clearly, because of concerns about climate change and dependence on foreign sources of energy, the U.S. will expand its use of renewable energies and alternative-transportation fuels. Eventually, the U.S. might meet a large percentage of energy demand via renewables, but such a feat will not be achieved quickly, nor will it come without significant economic cost. Fostering economic prosperity and protecting the environment are both important goals. Informed policymaking will require an honest accounting of the time and expense that an energy-economy makeover could entail.

<< PREVIOUS      NEXT >>



Download PDF (3MB)
Or request a hardcopy



Clarice Smith
Deputy Director, Communications
Manhattan Institute
(212) 599-7000




Copyright The Manhattan Institute 2009