What’s at Stake? Two Different Approaches to Climate Change – Part II The NHTSA Fuel-Efficient Vehicle Rule Draft Environmental Impact Statement

As introduced in Part I of this two part posting, two recently released documents – the Intergovernmental Panel on Climate Change report, Global Warming of 1.5°C Summary for Policymakers (IPCC Summary), issued on October 8, 2018, and the Safer Affordable Fuel-Efficient Vehicles Rule for Model Year 2021-2026 Passenger Cars and Light Trucks Draft Environmental Impact Statement (EIS), issued by the National Highway Traffic Safety Administration in July 2018 – provide a stark contrast in how to respond to the threat posed by climate change.

The IPCC Summary, which was addressed in Part I, issues a drastic call to action to the world to try to limit mean anthropogenic global warming to 1.5°C above pre-industrial levels in order to avoid potentially irreversible threats to human societies and the global environment. To stabilize warming to 1.5°C by 2040 (the year in which warming is projected to reach 1.5°C at the current rate of warming), the IPCC Summary calls for drastic transformative global action, stating that:

Pathways limiting global warming to 1.5°C with no or limited overshoot would require rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems (Sec. C2).

Essentially, net CO2 emissions globally must be reduced to zero through a combination of “supply-side” (energy source) and “demand-side” (energy use) techniques in the next 30-years.

In contrast, the EIS – the subject of this post – essentially accepts that the mean global temperature will warm by 3.5°C (6.3°F) by the end of the century, and in this context, argues that the comparative amount of additional CO2 admitted to the atmosphere and the estimated associated rise in atmospheric temperature resulting from weakening fuel efficiency standards, when compared to the values associated with a 3.5°C temperature rise, are small and not a cause for concern.

The EIS analyzes the potential environmental impacts of proposed revisions to the Corporate Average Fuel Economy (CAFÉ) standards for passenger cars and light trucks previously proposed for mileage years (MY) 2022–2026. The analysis compares the potential environmental impacts of nine alternatives for setting fuel economy standards, comprised of eight potential alternatives and a No Action Alternative (NAA). The NAA, which provides a baseline to which the other eight alternatives are compared, assumes that NHTSA would not amend the previously proposed CAFE standards and that the MY 2025 CAFE standards would continue through the year 2100.

Of the eight alternatives, the NHTSA picked Alternative 1 as its “Preferred Alternative” (PA). The PA requires a 0% average annual fleet-wide increase in fuel economy for both passenger cars and light trucks for MY 2021–2026, and would reduce average fleet mileage from 46.8 mpg to 37 mpg, while increasing US fuel consumption by 206 billion gal. and CO2 emissions in the year 2100 by 11%. (pg. S-3 to S-6, S-14). The impacts of the PA on “global mean surface temperature, precipitation, sea level, and ocean pH” are rationalized as being “extremely small in relation to global emissions trajectories,” such that, “they would only marginally increase the potential risks associated with climate change.” (pg. S-14, S-20).

According to the EIS, how small?

  • Estimated COconcentrations in the atmosphere for 2100 would range from 789.76 ppm under the PA to approximately 789.11 ppm under the NAA (a .65 ppm increase)(pg. S-15);
  • Global mean surface temperature is projected to increase by approximately 3.48°C (6.27°F) under the NAA by 2100, and would increase by an additional 0.003°C (0.005°F) under the PA. (pg. S-15);
  • Compared with projected total global COemissions of approximately 4.1 MMTCO2 (million metric tons of CO2 ) from all sources from 2021 to 2100, the impact of the PA is expected to increase global CO2 emissions by 0.18% by 2100. (pg. S-18).

It is important also to understand that the economic justification for the “marginal” impacts of the PA, contained in a companion Preliminary Regulatory Impact Analysis (PRIA), released in July 2018, are based on the revisions to the social cost of carbon calculation implemented earlier this year – limiting consideration of impacts only to the U.S. and using a higher discount rate. (PRIA, pg. 1062-63) (See The Social Cost of Carbon – A Crucially Important Number Few Have Heard of and its Potential Impact on Environmental Regulations)

In order then to justify rolling back CAFÉ standards, the EIS took as inevitable the “reasonable” worst-case global temperature increase scenario, assumed no effort would be made by the world to avoid such a temperature rise, completely ignored the potential catastrophic affects of such a temperature rise, abandoned any pretense that the US would attempt to meet its commitments under the Paris Agreement, and employed an unjustified revision to the social cost of carbon.

In other words, the greater the underlying numbers are, the smaller the proposed impacts appear. That such a course of action could even be contemplated in light of the IPCC report’s urgent exhortation to try to limit the rise in global temperatures to 1.5°C, by basing its actions on an “inevitable” temperature increase of 3.5°C, is incredible. To put this document into context, the changes to the climate system, with the associated impacts, are occurring with only a 1.0°C average temperature increase and an average atmospheric CO2 concentration of 410 ppm (the highest concentration in at least the last 800,000 years). What do the authors of the EIS think is going to happen with a 3.5°C temperature increase and a doubling of the average global CO2 concentration?

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