The wolverine is unique among mammals in that it is heavily dependent on spring snow pack. Deep snow is required for successful wolverine reproduction because female wolverines dig elaborate dens in the snow for their offspring. These dens are not only insulating for the newborn kits, but also protect them from predators.

"While other species such as the Arctic fox or caribou are adapted to snow, their relationship with snow may not be as critical as that of the wolverine," NCAR's Synte Peacock told environmentalresearchweb. "Other species may be able to adapt if there is no spring snow, but without such protective dens, the wolverine probably cannot successfully reproduce."

From her simulations Peacock found that the wolverine faces a potential two-fold threat from future climate change. Firstly, under an emissions scenario somewhere between RCP4.5 (medium-low emissions) and RCP8.5 (high emissions), spring snow cover is likely to fall to zero or near-zero levels by the middle of the 21st century in present-day wolverine habitats in the contiguous US.

Secondly, maximum daily temperatures in August are likely to show dramatic increases under a high emissions scenario comparable to RCP8.5. "The wolverine does not currently tolerate average maximum August temperatures much higher than 22°C," said Peacock. "Under the high emissions scenario, it is estimated that the average August will have between 20 and 31 days in which the maximum temperature is above 32° by the end of the 21st century."

Peacock warns that if we follow an emissions scenario of between RCP4.5 and RCP8.5, it is likely that the wolverine, faced with the double threat of rapidly decreasing spring snow cover and rapidly increasing summer temperature, will have lost most of its present-day habitat in the contiguous US by the end of the 21st century.

Peacock's concerns are echoed by the US Fish and Wildlife Service, which has found that wolverines in the contiguous US warrant protection under the Endangered Species Act because of the threat to their habitat due to climate change. However, because the Service's evaluation found that the effects from climate change, while serious, are not imminent, it has decided that the wolverine will be added to the list of candidates for Endangered Species Act protection, where its status will be reviewed annually. As a candidate species, the wolverine does not receive protection under the Act.

How the disappearance of wolverines would impact the ecosystem as a whole is unclear. They are solitary animals, with one wolverine's territory often covering a few hundred square miles. "There are so few wolverines in the US and they are so elusive that it is difficult to study them," said Peacock. "The impact of their disappearance would probably be relatively low and it is possible that the wolverine may continue to thrive in parts of Canada and Scandinavia where conditions are cold year-round and snow cover persists throughout spring."

Peacock reports her work in Environmental Research Letters (ERL).

This news article was modified slightly on 9/2/11.