The changing climate in northwest Wyoming is cited as a source of concern for some of Yellowstone National Park’s key natural resources, according to a new report from park managers.
Released Tuesday, “The State of Yellowstone Vital Signs and Select Park Resources” says average temperatures are exceeding historical norms resulting in a variety of changes to the ecosystem. According to the report, highlights of those changes include a longer growing season that favors both land and aquatic invasive species; altered stream flows, in part due to declining snow pack and peak river flows that are happening earlier in the year; and alpine plant life, water quality and some wildlife being negatively affected by warmer temperatures.
“Climate is a driving force behind many ecological processes. For example, average temperature and moisture determine which species can live in an area, the rate at which they grow, and the frequency and severity of forest fires,” the report says.
At Mammoth Hot Springs, the five-year running mean of average annual daily maximum temperature has increased by 2.1 degrees Fahrenheit and the average annual daily minimum temperature has increased by 3.9 degrees. The five-year running mean of annual peak snowpack (expressed as peak snow water equivalent) at the Northeast Entrance has declined 30 percent since 1966.
Snowy conditions have been prevailing for a shorter period during the year, the report says. The 10-year running mean of winter length — that’s the annual number of days with snow water equivalent greater than zero — decreased 15 percent between 1966–2017, dropping from 216 to 183 days.
“A greater proportion of annual precipitation will likely fall as rain rather than snow. Instead of being stored in the snowpack and gradually released during the year, this rain will be rapidly lost to streams and unavailable for plants and animals during the growing season,” the Yellowstone Center for Resources reports. “The snow that does accumulate will likely melt more quickly as a result of the projected warming trends, producing earlier and more intense spring runoff.”
The Yellowstone Center for Resources is responsible for research and monitoring of the park’s natural resources. The center employs a network of park specialists and scientists to protect park resources. Yellowstone also relies on more than 135 independent research groups that conduct work annually.
The report, which is the fourth compilation since 2005, highlights 41 natural and cultural resources; 21 are identified as vital signs and 20 as select park resources. Each resource summary includes resource history and background information, results of research and monitoring, current status and trends and prioritized future concerns.