I. INTRODUCTION II. GREENHOUSE REDUCTION BY THE NUMBERS: SCIENCE VS. POLICY III. A BRIEF SURVEY OF CLEAN AIR ACT REGULATION TO DATE FOR GREENHOUSE GASES: VAST POTENTIAL BUT LITTLE PROGRESS A. Mobile Sources of Pollution 1. Section 202 Standards for Automobiles and for Medium- and Heavy-Duty Trucks 2. Section 231 Standards for Aircraft and Section 213 Standards for Other Mobile Sources B. Stationary Sources of Pollution 1. New Source Performance Standards 2. New Source Review IV. CRITERIA AIR POLLUTANT DESIGNATION, NATIONAL AMBIENT AIR QUALITY STANDARDS, AND STATE IMPLEMENTATION PLANS FOR GREENHOUSE GASES A. The NAAQS Process B. Benefits of a NAAQS for Greenhouse Gases C. Challenges and Criticisms Related to a Greenhouse Gas NAAQS 1. The Section 111(d) Trade-off.... 2. NAAQS Attainment for a Globally WellMixed Gas 3. Allocating State Reductions under a Greenhouse Gas NAAQS 4. Fear of Political Backlash V. CONCLUSION I. INTRODUCTION Dangerous climate change is upon us. Reports of stronger storms, longer droughts, heat waves, crop failures, melting sea ice, and species declines are now ubiquitous. These and other impacts of climate change are certain to worsen in the coming years. As NASA's James Hansen and his colleagues warned in 2008, atmospheric carbon dioxide (C[O.sub.2]) levels are already unsafe. Without deep and rapid emission reductions, changes to the Earth's climate and ecosystems will render our planet unrecognizable: If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that C[O.sub.2] will need to be reduced from its current 385 ppm [parts per million] to at most 350 ppm, but likely less than that. (1) Despite similarly urgent warnings from scientists around the world, greenhouse gas emissions continue largely unabated. At the end of 2011, atmospheric C[O.sub.2] was at 390 ppm and rising. (2) The 2008 election of Barack Obama, who pledged to reduce greenhouse emissions, created expectations that the United States government would finally heed scientific warnings about the urgency of climate change. However, any sense of momentum towards meaningfully addressing the climate crisis stalled with the defeat of economy-wide climate legislation in the 111th Congress, the concurrent failure of international climate negotiations in Copenhagen in late 2009, and the 2010 election of a new Congress openly hostile to any form of greenhouse regulation. Consequently, the leading effort to tackle greenhouse emissions on a national level has been the Environmental Protection Agency's (EPA) nascent regulation of C[O.sub.2] and other greenhouse gases as pollutants under the forty-year-old Clean Air Act (CAA or Act). Despite legal challenges and legislative attacks by greenhouse polluters and their defenders in Congress, the EPA's implementation of several provisions of the CAA is now underway. Greenhouse gas-limiting rules for automobiles are finally in place, and emissions limitations now apply to C[O.sub.2] from some of the largest smokestack sources. Nevertheless, the EPA's efforts to date have failed to reduce the United States' overall greenhouse gas emissions. In fact, under provisions for regulating tailpipe emissions from cars and trucks, total annual C[O.sub.2] emissions from the vehicle sector will still increase beyond current levels. Similarly, new greenhouse gas-constrained permits for coal-fired power plants have provided little or no C[O.sub.2] reductions. In short, while the EPA's early greenhouse gas regulations will reduce the rate at which United States greenhouse gas emissions would rise absent such regulation, they have not yet reduced or even stabilized emissions at current levels, much less reduced them to the degree recommended by scientists to avert dangerous climate change. …