Over the coming decades, experts estimate that twenty-five percent of all plant and animal species may go extinct. Climate change directly contributes to species extinction through ecosystem shift, and accelerates other drivers of extinction such as destruction of habitat and pollution. The Endangered Species Act is the only legal tool in the United States to directly protect against the threat of species extinction, and critical habi­tat designations under the Endangered Species Act provide a way for the government to protect a species’ habitat and preserve biodiversity. Unfor­tunately, the Trump Administration’s recently promulgated regulations hinder, rather than bolster, federal agencies’ efforts to save endan­gered species. By severely restricting the designation of critical habitat, the gov­ernment has suppressed its own ability to respond to the effects of climate change on endangered and threatened species. This Note pro­poses a defini­tion of the term “habitat” in the Endangered Species Act that comports with current scientific understandings of the term and would allow federal agencies to account for climate change when designating critical habitat. The definition reflects the dynamic and tempo­rally vari­able nature of species’ habitats, allowing for the designation of currently unoccupied areas that will support species’ existence in the future. This definition would clarify the government’s role in protecting species’ habitats while also complying with the text and purpose of the Endangered Species Act.

The full text of this Note can be found by clicking the PDF link to the left.


The dusky gopher frog, a spotted, stocky amphibian named for its dark color and tendency to live underground, resides in longleaf pine forests that were once abundant in coastal Alabama, Louisiana, and Mississippi. 1 Weyerhaeuser Co. v. U.S. Fish & Wildlife Serv., 139 S. Ct. 361, 365 (2018). Unfortunately for the frog, humans have cleared over ninety-eight percent of its habitat for farming, development, and timber planta­tions, 2 Id. and it now holds the unhappy distinction of being one of the hun­dred most endangered species in the world. 3 Recovery Plan for Endangered Frog Available, U.S. Fish & Wildlife Serv. (Sept. 9, 2015), [] (last updated Sept. 19, 2018). By 2001, when the U.S. Fish and Wildlife Service (FWS) listed the species as endangered under the Endangered Species Act (ESA), the frog’s wild population had dwindled to a hundred individuals occupying a single pond in Mississippi. 4 Weyerhaeuser, 139 S. Ct. at 365. Ten years later, when FWS designated critical habitat for the frog, the agency deter­mined that solely protecting existing areas where the frog lived would not “adequately ensure the frog’s conservation” because an extreme weather event or infectious disease could wipe out the whole species. 5 Id. at 366; see also Adam Liptak, The Dusky Gopher Frog Loses a Round in the Supreme Court, N.Y. Times (Nov. 27, 2018), (on file with the Columbia Law Review). To combat this risk, FWS also designated private land in Louisiana as unoccupied critical habitat, essential for the species’ survival. 6 Weyerhaeuser, 139 S. Ct. at 366. The dusky gopher frog had not been seen in this Louisiana area since 1965, but with restoration efforts, FWS felt the land could serve as suitable habitat for the species in the future. 7 Id. The private landowners, who had hoped to develop the site, sued the government, arguing that their land could not be designated as “critical habitat” for the frog if the frog could not currently live there. 8 Id. at 367.

At the end of 2018, the dispute about the dusky gopher frog’s habitat had advanced to the Supreme Court as Weyerhaeuser Co. v. U.S. Fish & Wildlife Service. 9 Id. at 361. However, in its decision, the Court failed to clarify whether an area must be currently habitable by a species to be designated as “criti­cal habitat.” 10 Id. at 368–69 (“[T]he statutory definition of ‘critical habitat’ tells us what makes habitat ‘critical,’ not what makes it ‘habitat.’ . . . The court . . . had no occasion to interpret the term . . . . Accordingly, we vacate the judgment below and remand . . . .”). The Court determined only that the ESA “does not authorize the Secretary to designate the area as critical habitat unless it is also habitat for the species.” 11 Id. at 368. The Court remanded the case to the Court of Appeals for it to interpret the meaning of the word “habitat.” 12 Id. at 369.

Following the Court’s decision, FWS settled with the landowners and entered into a consent decree vacating the designation of the disputed area as critical habitat for the dusky gopher frog. 13 Consent Decree at 3, Markle Interests, LLC v. U.S. Fish & Wildlife Serv., No. 13-cv-234 (E.D. La. July 3, 2019). The original critical habitat designation for the dusky gopher frog was promulgated during the Obama Administration, but by the time the case had advanced to the Supreme Court, the Trump Administration was in power. The Trump Administration’s support for private property rights likely influenced FWS’s willingness to settle with the landowners. See Tate Watkins, After 8 Years of Dusky Gopher Frog Drama, Court Settlement Provides Relief for Louisiana Landowner, Prop. & Env’t Rsch. Ctr. (July 9, 2019), []. Therefore, the lower courts did not interpret the definition of “habitat” in the critical habitat provision of the ESA.

In August 2019, FWS and the National Marine Fisheries Service (NMFS) (together, “the Services”) issued new rules severely weakening protections for endangered species. 14 Darryl Fears, New Trump Rules Weaken Wildlife Protections, Wash. Post (Aug. 12, 2019), (on file with the Columbia Law Review). The regulations pertained in part to critical habitat designations. 15 Zack Strong, Critical Habitat: The Next Endangered Species?, Nat’l Rsch. Def. Council (Sept. 25, 2019), []. Though the 2019 regulations leave the term “habitat” undefined, they severely curtail the Services’ ability to designate unoccupied areas as critical habitat for an endangered species, and they make it more difficult for the Services to designate critical habitat in general. 16 Id. The regulations reference Weyerhaeuser as support for the new restrictions on critical habitat designations, 17 Endangered and Threatened Wildlife and Plants; Regulations for Listing Species and Designating Critical Habitat, 84 Fed. Reg. 45,020, 45,022 (Aug. 27, 2019). and are being challenged by two lawsuits, one brought by environmental groups 18 Second Amended Complaint for Declaratory & Injunctive Relief, Ctr. for Biological Diversity v. Bernhardt, No. 19-cv-05206 (N.D. Cal. filed June 4, 2020); Complaint for Declaratory & Injunctive Relief, Ctr. for Biological Diversity, No. 19-cv-05206 (N.D. Cal. filed Aug. 21, 2019) [hereinafter Ctr. for Biological Diversity Complaint]. and another brought by state attorneys general. 19 Complaint for Declaratory & Injunctive Relief, California v. Bernhardt, No. 19-cv-06013 (N.D. Cal. filed Sept. 25, 2019) [hereinafter California Complaint]. These rules come a few months after the UN released a report showing that within decades, nearly one million species risk extinction. 20 World Is ‘On Notice’ as Major UN Report Shows One Million Species Face Extinction, UN News (May 6, 2019), []. In December 2020, the Services supplemented these regulations with a newly promulgated rule specifically defining “habitat” for critical habitat designations. 21 Endangered and Threatened Wildlife and Plants; Regulations for Listing Endangered and Threatened Species and Designating Critical Habitat, 85 Fed. Reg. 81,411 (Dec. 16, 2020) (to be codified at 50 C.F.R. pt. 424). Although the timing of this finalized rule precludes an in-depth analysis in this Note, section II.C.4 briefly discusses the rule. Like the 2019 regulations, this rule impedes the Services’ capabilities to conserve endangered species by protecting their habitats.

The ESA is the nation’s strongest law protecting endangered species and the often-fragile biodiversity in the United States. 22 Anna T. Moritz, Kassie R. Siegel, Brendan R. Cummings & William H. Rodgers, Jr., Biodiversity Baking and Boiling: Endangered Species Act Turning Down the Heat, 44 Tulsa L. Rev. 205, 213 (2008). As climate change rapidly changes environments and puts ever more species at risk, critical habitat designations could serve as an effective tool in the fight to protect biodiversity. Instead, the new regulations weaken and flout the ESA’s conservation mandate. This Note proposes a definition of the term “habitat” in the ESA that would allow the Services to account for climate change when designating critical habitat and therefore protect land essential for the conservation of endangered and threatened species in the future. This definition, along with more progressive implementation regulations for critical habitat designations, would clarify the Services’ role in protecting species’ habitats, while also complying with the text and purpose of the ESA and the Court’s decision in Weyerhaeuser.

Part I provides background and legislative history about the ESA and the role of critical habitat designations within the ESA, and discusses past agency regulations and case law concerning critical habitat designations. Part I also summarizes and addresses the Weyerhaeuser decision. Part II discusses the growing threat of mass extinction around the world and the associated need for legal regimes protecting biodiversity. Part II presents examples of ESA agency actions that have taken climate change into account. These examples demonstrate the scientific approach necessary to conserve species endangered by climate change, and Part II contrasts these actions with an analysis of recent regulations crippling the Services’ powers under the ESA. Part III argues that “habitat” must be defined broadly in order to allow the Services to fulfill their conservation mandate under the ESA, and proposes a scientifically supported definition of “habitat” that could be adopted by a future administration. This definition and related implementation regulations would allow the Services to make effective and forward-looking critical habitat designations, a necessary step to protect endangered and threatened species in an era of mass extinction. Part III also presents two case studies of species that may soon be listed as threat­ened or endangered and would benefit from the proposed definition, as climate change will likely cause their habitats to shift in the coming dec­ades. These case studies epitomize the need for a definition of “habitat” that will allow the Services to utilize climate science and modeling in their conservation strategies.