How did we calculate reference case emissions?

U.S. Business-as-Usual (BAU) emissions include the projected release of six gases: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6), as well as CO2 natural carbon sinks. BAU is measured taking 2014 as the base year, and includes implemented policies such as MY 2022-2025 CAFE standards that may change if EPA weakens these standards after mid-term review. The high and low BAU scenarios, in million metric tons of CO2 equivalent (million metric tons CO2e), are provided below.

Projected Greenhouse Gas Emissions Through 2030 (MMTCO2-eq)

Pollutant: 2005  2014  2020 2025 2030
CO2 6,123 5,556 5,477 5,525 5,531
CH4 717 731 670 674 682
N2O 398 404 338 335 334
HFC 120 167 255 311 324
PFC 7 6 5 5 7
SF6 14 7 9 9 10
NF3 0.5 0.5
Sinks – low -699 -762 -1,044 -908 -689
Sinks – high -699 -762 -1,191 -1,201 -1,118
Net GHGs – low 6,680 6,108 5,563 5,658 5,770
Net GHGs – high 6,680 6,108 5,710 5,951 6,199

Note: Historic emissions obtained from EPA’s Greenhouse Gas Inventory 1990-2014.

      • Carbon Dioxide: Future U.S. carbon dioxide emissions are estimated based on the U.S. Energy Information Administration’s 2016 Annual Energy Outlook (2016 AEO), using the reference scenario without the Clean Power Plan. The projections account for all federal and state regulations implemented as of the end of February 2016. The energy-related CO2 emissions figures obtained from the 2016 AEO are adjusted upward to obtain a rough estimate of total CO2 emissions. We use a 1.03 adjustment factor, which roughly represents the historic ratio between total and energy-related CO2 emissions in the United States.
      • CH4, N2O, HFCs, PFCs, and SF6: Projected U.S. emissions of the remaining five gases are taken from the Second U.S. Biennial Report to the UNFCCC and represent the “current policies” scenario. These estimates have been developed by the U.S. Environmental Protection Agency and take into account policies under implementation as of mid-2015.
      • Land sinks:The volume of CO2 removals by U.S. land sinks, particularly forests, are the largest source of uncertainty in future GHG emissions. Historically, this figure has been significant—for example, land sinks offset approximately 15 percent of total emissions in each of the past five years. Although it is possible that U.S. forests will continue this high rate of carbon sequestration through 2025 and beyond, some studies now indicate that the CO2 absorption rate may begin to decline due to increased forest disturbances (e.g., drought, wildfires and the spread of diseases), slower forest growth, and other factors. To account for this variability, the Second Biennial Report provides both a low and high carbon sequestration figure. Both are included in our calculations.

What do emissions look like without the land sink?

Graph: Emissions Trajectory Without Sinks

Our projections for carbon dioxide removals by natural land sinks are taken from the U.S. Second Biennial Report (SBR) to the UNFCCC, published in early 2016. Since then, the U.S. EPA has substantially revised its methodology for calculating historic sinks. We are not aware whether or not the revised methodology is consistent with that used to estimate future sinks in the SBR. Because the two may not, in fact, be consistent, the _net_ emissions graphic may misrepresent the degree to which the U.S. is meeting its climate commitments, all of which are based on net emissions. Gross emissions remove the uncertainty related to the land sink and allow us to more clearly visualize how projected emissions compare with historic totals.

How did we calculate emissions reductions below reference case?

We obtain the total abatement potential of policy action by adding up the projected impact of all active policies within a given year. This sum is then subtracted from the reference case emissions projections. Expected reductions are obtained from the rules themselves or the analyses that accompany the publication of each proposal or final regulation, most often the Executive Branch’s formal regulatory impact analysis or environmental assessment, but also respected independent analysis. It is important to note that this aggregate approach simplifies the complex relationships among policies and ignores interdependencies, feedback effects, or any other indirect impacts of implementation. Methodologies for obtaining the mitigation impacts of specific policies are discussed in the policy descriptions.

How do I cite the Backtracker?

“Trump Backtracker” Climate Advisers, 2017. Available at: https://www.climateadvisers.com/trumpbacktracker. (accessed 7 Aug 2017).

Who do I contact for more information?

For questions or comments, please contact Maria Belenky by email at [email protected] or phone at +1 202-350-4941

What other resources about the U.S. emissions trajectory are available?