What Would It Take to Reduce U.S. Greenhouse Gas Emissions 80 Percent by 2050?

In its submission to the Paris Conference of the Parties (COP) 21, the United States expressed an aspiration to reduce its greenhouse gas (GHG) emissions by 80 percent from 2005 levels by 2050. This is not a commitment, but rather a publicly stated goal thought to be consistent with the global goal of keeping the anthropogenic rise in global mean surface temperature to less than 2 C. This article investigates the cost of attaining this goal. One way of reducing GHG emissions is to move away from using fossil fuels. Another option is to continue fossil fuel use but to capture and store the resulting carbon dioxide (CO2) emissions. At this point, moving away from carbon-based energy would appear to be the more achievable of the two options. In this article, I go some way towards exploring this alternative and examine the financial implications of the U.S. economy, one of the largest in the world and the second largest emitter of GHGs, moving largely away from carbon-based energy by 2050. First, let me be clear about what I am not doing here. I am not asking if the U.S. economy will of its own volition move away from fossil fuels (that question has been asked recently by Covert, Greenstone, and Knittel 2016). And I am not analyzing the policy measures that would be required to lead to a decarbonized economy, though I will make some remarks about them. What I am doing is investigating in a rather informal way some of the conditions necessary for a transition to a largely carbon-free economy over the next three decades. I try to make calculations that are correct to within orders of magnitude rather than being exact, which is probably the best one can do for events that are three decades in the future. I also try to do this in a