Annual precipitation at Mammoth Hot Springs, Yellowstone National Park, 1941–2016. The running mean is based on a time series with 21.1 percent missing values. The five-year moving mean includes the current year and previous four years. Graphic: Yellowstone Center for Resources

By Laura Zuckerman
10 September 2018
PINEDALE, Wyoming (Reuters) – Hotter, drier conditions have led to more severe wildfires in Yellowstone National Park, while growing numbers of visitors have harmed everything from prized hydrothermal features to its famed grizzly bears, the park said in a report on Monday.
Average temperatures in Yellowstone, which has been designated as both World Heritage and Biosphere Reserve sites by a United Nations panel, are exceeding historical norms even as climate change is blamed for a string of fires that have increased in size and which last longer, according to the study.
The 60-page The state of Yellowstone vital signs and select park resources, 2017 [pdf] report is one of just four compiled in the past decade. They are designed to track one of the largest, nearly intact temperate ecosystems in the world.Yellowstone is celebrated for geothermal areas that contain about half the world’s active geysers, as well as forests, mountains, meadows, rivers and lakes considered a crucial sanctuary for the largest concentration of diverse wildlife in the Lower 48 states. The report shows it has seen warmer summers with less moisture and shorter winters in recent years.At Mammoth Hot Springs in the northwest of the park, for example, the average annual daily minimum temperature has increased by 3.9 degrees Fahrenheit from 1941 to 2016 even as total annual precipitation has for the most part been below the long-term mean of 15.3 inches and snowpack has generally declined, scientists found.

Trumpeter swan nest attempts and cygnets fledged in Yellowstone National Park, 1986–2016. Graphic: Yellowstone Center for Resources

Researchers noted an increase in the size of wildfires that impact vegetation and degrade air quality and said the future holds more of the same.“If climate trends continue along their current trajectory, fires within the park will continue to be larger (and) burn for longer durations,” according to the report. [more]

Yellowstone hit by global warming, increased visitation: report