The opinion of the court was delivered by: Henry H. Kennedy, Jr. United States District Judge
MEMORANDUM OPINION AND ORDER
Plaintiffs Center for Biological Diversity, Center for Food Safety, Friends of the Earth, International Center for Technology Assessment, and Oceana (collectively, "plaintiffs") bring this action against the U.S. Environmental Protection Agency and its Administrator, Lisa Jackson (collectively, "EPA"), seeking to compel agency action with regard to the regulation of emissions by non-road vehicles and engines, including marine vessels and aircraft, under the Clean Air Act ("the Act"), 42 U.S.C. § 7401 et seq. Before the Court are two joint motions to intervene in support of EPA, the first [#10] on behalf of the Air Transport Association of America ("ATA") and the National Business Aviation Association ("NBAA") and the second [#12] on behalf of the Aerospace Industries Association of America ("AIA") and the General Aviation Manufacturers Association ("GAMA"). Because these motions raise nearly identical issues, the Court addresses them together, referring to all of the putative intervenors collectively as "movants." Upon consideration of the motions, the oppositions thereto, and the record of this case, the Court concludes that both motions should be denied.
A. The Clean Air Act and Aircraft Emissions Regulations
The Clean Air Act gives EPA the authority to regulate "air pollutants," a category that it defines very broadly. See 42 U.S.C. § 7402(g); Massachusetts v. EPA, 549 U.S. 497, 506--10 (2007) (describing the history of the Act and efforts to address climate change). The Act also creates a specific regulatory scheme for emissions from "nonroad" engines and vehicles (other than train locomotives), including aircraft. See 42 U.S.C. § 7547(a). Under that framework, EPA "shall" conduct a study of emissions from such sources, id. § 7547(a)(1), and determine whether they are "significant contributors to ozone or carbon monoxide concentrations in more than 1 area which has failed to attain the national ambient air quality standards for ozone or carbon monoxide." Id. § 7547(a)(2). If that determination is affirmative, EPA must promulgate appropriate regulations. Id. § 7547(a)(3).
EPA may also promulgate regulations if it determines that any other emissions from such sources "significantly contribute to air pollution which may reasonably be anticipated to endanger public health or welfare." Id. § 7547(a)(4). Similarly, the Act states that EPA "shall, from time to time, issue proposed emission standards applicable to the emission of any air pollutant from any class or classes of aircraft engines which in [its] judgment causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare." Id. § 7571(a)(2)(A). These predicate determinations are commonly referred to as "endangerment findings."
Pursuant to its authority under the Act, EPA has adopted aircraft emission standards "covering certain criteria pollutants or their precursors and smoke; these standards do not currently regulate emissions of CO2 and other [greenhouse gases]." Regulating Greenhouse Gas Emissions Under the Clean Air Act, 73 Fed. Reg. 44,354, 44,469 (July 30, 2008). In setting emissions standards, EPA has historically cooperated with the Federal Aviation Administration and the International Civil Aviation Organization, id., which is an agency of the United Nations charged with fostering the safe and orderly growth of international civil aviation.
Between October 2007 and January 2008, plaintiffs submitted three petitions to EPA, asking it to use its authority under the provisions described above to regulate greenhouse gas emissions from marine vessels, aircraft, and other nonroad vehicles. Compl. ¶¶ 48--50. EPA subsequently issued an Advance Notice of Proposed Rulemaking regarding greenhouse gas emissions, see 73 Fed. Reg. 44,354, but plaintiffs assert that it was not responsive to their petitions because it failed to determine whether greenhouse gas emissions from these sources endanger public health or welfare or to establish a plan for regulating such emissions. Compl. ¶¶ 55--59. Accordingly, plaintiffs filed a notice of intent to sue as required by the Act, Compl. ¶ 53; see 42 U.S.C. § 7604(a), (b)(1), and commenced this action, seeking to compel EPA to respond to their petitions. Shortly thereafter, movants, who represent numerous manufacturers and operators of aircraft, aircraft components, and aircraft engines,*fn1 sought leave to intervene in support of EPA. See AIA & GAMA's Mem. in Supp. of Mot. for Leave to Intervene ("AIA & GAMA Mem."); ATA & NBAA's Mem. in Supp. of Mot. for Leave to Intervene ("ATA & NBAA Mem."). EPA takes no position on movants' intervention; plaintiffs oppose it.
Movants seek leave to intervene in this action on two grounds: they assert that they are entitled to intervene as of right under Federal Rule of Civil Procedure 24(a); they alternatively seek permissive intervention under Rule 24(b). Plaintiffs respond that movants do not meet either intervention standard, and further assert that movants may not intervene here because they lack standing to do so. The Court first addresses intervention as of right.
A. Intervention as of Right Under Rule 24(a)
Movants assert that they are entitled to intervene as of right in this action because they have made the necessary showing under Rule 24(a).*fn2 Plaintiffs disagree, and further challenge movants' Article III standing to intervene. Movants respond that they do not need to establish standing in order to intervene as of right. Because standing goes to the Court's jurisdiction, ...