Climate Change Attribution Science and the Endangered Species Act

Abstract

Climate change poses an enormous risk to plant and animal species across the planet. Mean global temperatures have already increased by approximately 1ºC, causing environmental changes that affect species abundance, distribution, behavior, physiology, genetics, and survival prospects. These changes, combined with other human stressors, have already resulted in the extinction of some species and imperiled many others. In the United States, the Endangered Species Act (ESA) is the primary legal vehicle for the protection and management of species at risk of extinction. The statute and accompanying regulations outline a science-based framework for identifying endangered and threatened species, establishing critical habitat boundaries, and mitigating the harmful impacts of public and private-sector activities on listed species. Although climate change is not explicitly mentioned in the statute, there is no question that agencies must consider climate-related threats when implementing the ESA. This Article examines the uniquely important role of climate change detection and attribution research in federal decision-making and judicial review under the ESA. This research provides insights on how climate change is already affecting species and habitats and is therefore integral to decisions about: (i) whether to list a species as threatened or endangered on the basis of climate-related threats, and (ii) how to support species recovery through critical habitat designations and other management actions. Courts have held that attribution research qualifies as the “best available science” that must be considered in ESA decision-making and that agencies cannot ignore attribution research on the basis of uncertainty or imprecision where the data suggests that there is a probable threat to a species. They have also consistently upheld the federal government’s use of attribution data to support ESA protections for climate-imperiled species.