Carbon tax advocates say Congress should slap a price penalty on fossil fuels to make consumers bear the “social cost of carbon” (SCC) — the damage carbon dioxide (CO2) emissions allegedly inflict on public health and welfare via their presumed impacts on global climate.
What is the SCC? Depends on who you ask. Climate “hot heads” like Al Gore think the SCC is huge. “Lukewarmers” like Patrick Michaels think the SCC is less than the cost of the tax or regulatory burden required to make deep cuts in CO2 emissions. “Flatliners” like Craig Idso think the SCC is negative (i.e. CO2’s net impact is beneficial), because a moderately warmer climate is healthful and CO2 emissions nourish the biosphere.
In February 2010, the EPA and 11 other agencies issued a Technical Support Document (TSD) on the SCC. The TSD’s purpose is to enable federal agencies to incorporate the “social benefit” of CO2 emission reductions into cost-benefit estimates of regulatory actions.
The TSD recommends that agencies, in their regulatory impact analyses, use four SCC estimates, ranging from $5 per ton to $65 per ton in 2010:
For 2010, these estimates are $5, $21, $35, and $65 (in 2007 dollars). The first three estimates are based on the average SCC across models and socio-economic and emissions scenarios at the 5, 3, and 2.5 percent discount rates, respectively. The fourth value is included to represent the higher-than-expected impacts from temperature change further out in the tails of the SCC distribution.
Here’s where it gets interesting. Both the federal and state governments levy taxes on motor fuel. Motor fuel taxes are not called carbon taxes but their economic effect is the same — impose a price penalty on consumption. Moreover, via simple arithmetic any carbon tax can be converted into an equivalent gasoline tax and vice versa.
The point? Americans in every state except Alaska already pay a combined federal and state gasoline tax that is higher than a carbon tax set at $5, $21, or $35 per ton. Americans in five states pay a combined gasoline tax that is higher than a $65 per ton carbon tax. Americans in several other states pay a combined gasoline tax that is nearly as high as a $65 per ton carbon tax.
Carbon taxes are assessed per metric ton of CO2 emitted. Carbon taxes convert into gas taxes as follows. One gallon of gasoline when combusted yields 8.91 kilograms of CO2. One metric ton = 1,000 kilograms. Therefore, the quantity of CO2 emitted by a gallon of gasoline is 0.891% of a metric ton. If a carbon tax is set at $5, $21, or $35 per metric ton, then the carbon tax for gasoline, reflecting the estimated SCC, is about 4¢, 19¢, or 31¢ per gallon, respectively.
At 18.4¢ per gallon, the federal gasoline tax alone exceeds the TSD’s $5 per ton (4¢ per gallon) SSC estimate and nearly equals the $21 per ton (19¢ per gallon) SCC estimate. The U.S. average combined state and federal gasoline tax is 48.9¢ per gallon, 57% higher than a fuel tax (31¢ per gallon) based on the $35 per ton SCC estimate. See the chart below.
Source: American Petroleum Institute
A carbon tax set at $65 per ton translates into a 58¢ per gallon gasoline tax. Motorists in five states pay more: California (67.7¢ per gallon), New York (67.7¢ per gallon), Hawaii (66.7¢ per gallon), Connecticut (63.4¢ per gallon ), and Illinois (62.8¢ per gallon). Americans in several other states (the other red states in the map) pay a combined gasoline tax that is nearly as high.
Motor vehicles, of course, are not the only source of CO2 emissions in the U.S. economy. The transport sector as a whole accounts for about 29% of total U.S. greenhouse gas emissions. Nonetheless, as motor fuel consumers, almost all Americans already pay a de facto carbon tax exceeding three out of four U.S. Government estimates of the social cost of carbon, and tens of millions of Americans pay an effectual carbon tax exceeding the government’s high-end social cost of carbon estimate.
Carbon tax proponents might say the foregoing analysis is not relevant because the purpose of gas taxes is to pay for roads while the purpose carbon taxes is to limit environmental impacts. This criticism is itself irrelevant. Whether the tax on motor fuel is called a carbon tax or a gasoline tax, it has the same effects on consumer behavior and business investment. What the revenues are used for — roads & bridges, green tech R&D, health care, deficit reduction — is a separate issue.
So the next time a warmista says we should pay a carbon tax, cheerfully reply, “Been there, done that, each time I fill up at the pump.”