On April 4, 2016 U. S. District Court Judge Dana Christiansen vacated the U.S. Fish and Wildlife Service (FWS) withdrawal of the proposed listing of wolverine as a threatened species, reports the Wildlife Management Institute. The ruling has a number of significant implications to broader application of the Endangered Species Act (ESA).

The FWS initially proposed to list wolverine in 2010 due primarily to the anticipated impact of climate change on snow cover. Wolverines are believed to require deep, persistent snow cover during the denning season for successful reproduction, and two studies that modelled the impact of climate change predicted significant reductions in snow cover in the historic range of wolverines in the Rocky Mountains. After further review, however, the FWS concluded in 2014 that those studies were not sufficiently detailed to support a conclusion that the changes in snow cover, if they occurred, would threaten wolverines within the foreseeable future. The court found a number of flaws in the FWS' reasoning and ruled the withdrawal of the proposed rule "arbitrary and capricious." Judge Christiansen remanded the matter to the FWS in light of the court's findings.

Model-based predictions of the impact of climate change are increasingly being cited as the basis for listing species under the ESA. The FWS listed polar bears as threatened due to projected loss of sea ice and the National Oceanic and Atmospheric Administration (NOAA) is currently considering similar listings for a number of ice seal species for the same reason. Petitioners and plaintiffs who support listing wolverine as threatened also base their arguments on predicted impacts of climate change on spring snow cover. In making final decisions on listing species, both the FWS and NOAA must exercise their judgement on the reliability of the model projections, as well as the likelihood that predicted changes in ice or snow conditions will result in population-level effects on species.

In the case of wolverine, there was disagreement within the FWS regarding the adequacy of the science in terms of the reliability of the model projections and the impacts to the species. Although some FWS staff believed the science was sufficient to warrant listing wolverines, the final decision, made by FWS Regional Director Noreen Walsh, was to the contrary. Judge Christiansen posited that the final decision was not based on legitimate differences of interpretation, but due to political pressure exerted on the FWS by western states and other interests that oppose listing wolverines. The court pointed to evidence in the administrative record of the FWS' determination to support its ruling.

Few decisions made by the FWS and NOAA are more controversial or contested than those related to listing species under the ESA. Climate science is imprecise, particularly at finer scales, which requires FWS and NOAA decision-makers to exercise considerable judgement in reaching conclusions on listings. The administrative record of any such decision is likely to be littered with disagreement and suggestions of political pressure applied from multiple perspectives. The ruling in the wolverine case makes clear that courts will take a close look at the evidence when assessing the judgement of final decision-makers and overturn science-informed decisions if they disagree with the final conclusion. (cs)