there is a clear difference between actions that carry out authority under the Clean Air Act or other domestic law, and actions that would implement the Protocol. Thus, there is nothing inconsistent in assessing the extent of current authority under the Clean Air Act and maintaining our commitment not to implement the Protocol without ratification. Some brief background information is helpful in understanding the context for this question of legal authority. In the course of generating electricity by burning fossil fuels, electric power plants emit into the air multiple substances that pose environmental concerns, several of which are already subject to some degree of regulation. Both industry and government share an interest in understanding how different pollution control strategies interact. These interactions are both physical (strategies for controlling emissions of one substance can affect emissions of others) and economic (strategies designed to address two or more substances together can cost substantially less than strategies for individual pollutants that are designed and implemented independently). EPA has worked with a broad array of stakeholders to evaluate multiple-pollutant control strategies for this industry in a series of forums, dating back to the Clean Air Power Initiative (CAPI) in the mid-1990s. While the CAPI process focused on SO2 and NOx, a broad range of participants, including representatives of power generators, the United Mine Workers, and environmentalists, expressed support for inclusion of CO2 emissions, along with SO2, NOx, and mercury, in subsequent analyses. One conclusion that emerged from these analytical efforts is that integrated strategies using market-based "cap-and-trade" approaches like the program currently in place to address acid rain would be the most flexible and lowest cost means to control multiple pollutants from these sources. On March 11, 1998, during hearings on EPA's FY 1999 appropriations, Representative DeLay asked the Administrator whether she believed that EPA had authority to regulate emissions of pollutants of concern from electric utilities, including CO2. She replied that the Clean Air Act provides such authority, and agreed to Representative DeLay's request for a legal opinion on this point. Therefore, my predecessor, Jonathan Z. Cannon, prepared a legal opinion for EPA Administrator Carol Browner on the question of EPA's legal authority to regulate several pollutants, including CO2 emitted by electric power generation sources. The legal opinion requested by Rep. DeLay was completed on April 10, 1998. It addressed the Clean Air Act authority to regulate emissions of four pollutants of concern from electric power generation: nitrogen oxides (NO,,, sulfur dioxide (SO2), mercury, and CO, Because today's hearing is focused exclusively on CO2, I will summarize the opinion's conclusions only as they relate to that substance. The Clean Air Act includes a definition of the term "air pollutant," which is the touchstone of EPA's regulatory authority over emissions. Section 302(g) defines "air pollutant" as any air pollution agent or combination of such agents, including any physical, chemical, biological, [or] radioactive... substance or matter which is emitted into or otherwise enters the ambient air. Such term includes any precursors to the formation of any air pollutant, to the extent that the Administrator has identified such precursor or precursors for the particular purpose for which the term "air pollutant" is used. Mr. Cannon noted that CO, is a "physical [and] chemical substance which is emitted into... the ambient air," and thus is an "air pollutant" within the Clean Air Act's definition. Congress explicitly recognized emissions of CO2 from stationary sources, such as fossil fuel power plants, as an "air pollutant" in section 103(g) of the Act, which authorizes EPA to conduct a basic research and technology program te include, among other things, "[i]mprovements in nonregulatory strategies and technologies for preventing or reducing multiple air pollutants, including sulfur oxides, nitrogen oxides, heavy metals, PM-10 (particulate matter), carbon monoxide, and carbon dioxide, from stationary sources, including fossil fuel power plants." (Emphasis added.) The opinion explains further that the status of CO2 as an "air pollutant" is not changed by the fact that CO2 is a constituent of the natural atmosphere. In other words, a substance can be an “air pollutant" under the Clean Air Act's definition even if it has natural sources in addition to its man-made sources. EPA regulates a number of naturally-occurring substances as air pollutants because human activities have increased the quantities present in the air to levels that are harmful to public health, welfare, or the environment. For example, SO, is emitted from geothermal sources; volatile organic compounds (VOCs), which are precursors to harmful ground-level ozone, are emitted by vegetation. Some substances regulated under the Act as hazardous air pollutants are actually necessary in trace quantities for human life, but are toxic at higher levels or through other routes of exposure. Manganese and. selenium are two examples of such pollutants. Similarly, in the water context, phosphorus is regulated as a pollutant because although it is a critical nutrient for plants, in excessive quantities it kills aquatic life in lakes and other water bodies. While CO2, as an "air pollutant," is within the scope of the regulatory authority 2 provided by the Clean Air Act, this by itself does not lead to regulation. The Clean Air Act includes a number of regulatory provisions that may potentially be applied to an air pollutant. But before EPA can actually issue regulations governing a pollutant, the Administrator must first make a formal finding that the pollutant in question meets specific criteria laid out in the Act as prerequisites for EPA regulation under its various provisions. Many of these specific Clean Air Act provisions for EPA action share a common feature in that the exercise of EPA's authority to regulate air pollutants is linked to a determination by the Administrator regarding the air pollutant's actual or potential harmful effects on public health, welfare or the environment. For example, EPA has authority under section 109 of the Act to establish National Ambient Air Quality Standards for any air pollutant for which the Administrator has established air quality criteria under section 108. Under section 108, the Administrator must first find that the air pollutant in question meets several criteria, including that: it causes or contributes to "air pollution which may reasonably be its presence in the ambient air "results from numerous or diverse mobile or stationary sources...." Section 302(h), a provision dating back to the 1970 version of the Clean Air Act, defines "welfare" and states: all language referring to effects on welfare includes, but is not limited to, effects on soils, water, crops, vegetation, man-made materials, animals, wildlife, weather, visibility, and climate, damage to and deterioration of property, and hazards to transportation, as well as effects on economic values and on personal comfort and well-being, whether caused by transformation, conversion, or combination with other air pollutants. Thus, since 1970, the Clean Act has included effects on "climate" as a factor to be considered in the Administrator's decision as to whether to list an air pollutant under section 108. Analogous threshold findings are required before the Administrator may establish new source performance standards for a pollutant under section 111, list and regulate the pollutant as a hazardous air pollutant under section 112, or regulate its emission from motor vehicles under Title II of the Act. Given the clarity of the statutory provisions defining "air pollutant" and providing authority to regulate air pollutants, there is no statutory ambiguity that could be clarified by referring to the legislative history. Nevertheless, I would note that Congress' decision in the 1990 Amendments not to adopt additional provisions directing EPA to regulate greenhouse gases by no means suggests that Congress intended to limit preexisting authority to address any air pollutant that the Administrator determines meets the statutory criteria for regulation under a specific provision of the Act. I would like today to reiterate one of the central conclusions of the Cannon memorandum, which stated: "While CO2, as an air pollutant, is within EPA's scope of authority to regulate, the Administrator has not yet determined that CO2 meets the criteria for regulation under one or more provisions of the Act." That statement remains true today. EPA has not made any of the Act's threshold findings that would lead to regulation of CO2 emissions from electric utilities or, indeed, from any source. The opinion of my predecessor simply clarifies -- and I endorse this opinion - that CO2 is in the class of compounds that could be subject to several of the Clean Air Act's regulatory approaches. Thus, I would suggest that many of the concerns raised about |