Changing climate in the years ahead could make this scene at the warming hut at Madison Junction in Yellowstone a thing of the past, according to a new study/Kurt Repanshek

What now might be considered a "bad snow year" in Yellowstone National Park, one that limits snowmobile and snowcoach access, will in the not-too-distant future become the average snow year, according to a new study.

The study, recently published by PLOS ONE, builds on climatic forecasts for the park contained in a special climate change edition of Yellowstone Science published last year. The new study concludes that varying snow conditions "that are likely to prevail across Yellowstone in the future may require a switch to conventional automobiles in some areas that are currently allocated for snowmobiles, such as the west entrance road, while in contrast, some areas such as the south entrance road are likely to be suitable for oversnow use until the end of the century."

The authors ran three models before reaching their conclusions. In the end, the said that "(S)ince many factors influence Yellowstone's winter policies, it is not simple to decide exactly when it becomes more feasible to plow the roads and switch to conventional automobile travel. Nevertheless, park managers and local business owners would be well-advised to consider that traditional, metal-tracked snowmobiles and snowcoaches will likely become increasingly ill-adapted to the conditions that prevail on Yellowstone's roads in the winter."

Mike Tercek, who was the lead author for the Yellowstone Science article and authored the PLOS ONE article, said the new study builds on what the 2015 report found.

"Historical data show that Yellowstone's snowpack is already declining, as summarized in the Yellowstone Science article. The new article in PLOS ONE projects this existing trend out into the future," he said via email. "In the future, when we have bad snow conditions (i.e. not enough snow for snowmobiles) on Yellowstone's roads, people shouldn't conclude, as they often have, that it is an isolated incident. Those poor conditions will become increasingly more frequent. What is now considered to be a bad snow year will in a few decades be considered an average snow year."

While forecasts often can have a hard time predicting weather more than several days out, Tercek said predictions that stretch out over much longer periods "gets away from the short term noise and reveals the effects of the larger physical processes at work. Regarding this 'noise' or bumps in the data: Even though snowpack is in long term decline, there will still be some 'good' snow years even in late century, but these 'good' years will be progressively less frequent."

Most likely, the data show, Yellowstone's winters will be "squeezed" on both ends of the calendar.

"So far in the Yellowstone area, this shortening of the snow season has been due to warm spring temperatures arriving progressively earlier in the year. In most cases, the historical data do not show winter shortening consistently on the other end, i.e. warm autumn temperatures are not lasting longer. In the future, winter could be shortened on both ends," he said.

The prospect of more wheeled traffic in Yellowstone during the now-slow winter months could have an adverse impact on the park.

"A switch to conventional automobile travel during the winter would likely increase visitation to Yellowstone, as interior roads become accessible to people that do not possess the financial resources or specialized equipment needed for oversnow travel," the reported noted. "Also, as snow conditions in certain areas become unsuitable or unreliable, congestion might increase in the suitable areas that remain, a phenomenon that has already been observed in ski areas that have experienced snow decline. Increased tourism may in turn exacerbate the direct effects of climate change on natural resources, potentially threatening the iconic species and natural features that originally inspired the creation of many national parks across the country. The changing nature of winter travel in Yellowstone will become just one of many new challenges that climate change poses to the national park system."

Tercek said one option that might lessen the impact is expanding the use of "low pressure tires, rather than tracks, on the snowcoaches. These very large tires, approximately 5 feet tall, can be driven on either snow or pavement with efficiency," he said. "Vehicles using these tires are also much more fuel efficient than tracked vehicles. Since some roads will be affected by climate change much more than others, these vehicles would make it easier to transition through the patchy bare - to - snowy conditions that will likely prevail in the future. Snowmobiles, as opposed to snowcoaches, might not be as adaptable."