Yosemite National Park’s environment is healthy in many ways, yet Yosemite can be affected by environmental issues. Some of which, like climate change, are especially challenging because they originate outside the park. The list below documents how Yosemite scientists approach some of these issues.

Air Quality: Air pollution is currently recognized as one of the most significant threats to the resources of the Sierra Nevada. Sources are local, regional, and in some instances, global. The National Park Service in cooperation with state and other federal agencies are making concerted efforts to reduce the damage caused by air pollution. This is done by an intensive monitoring program, by offering support for research, and by expanding the education of park visitors concerned about the future of Yosemite National Park.

Climate Change: A pattern of warming during the past 30 years in the Yosemite region has resulted in thinner snowpacks replaced by rain. All climate models show warmer futures in central California, with temperatures at least 5 to 10 degrees Fahrenheit higher by the end of the century, especially as elevation increases. Why can’t this temperature change simply be assumed to be a natural variation? Scientists attribute the ongoing warming to society’s emission of greenhouse gases that have a long lifetime in the atmosphere, therefore, indicating a shift to a new climate. As we adapt to the warmer climate, we’ll need to gain the data to document it and to support ongoing management decisions.

Soundscape: The acoustic environment of any area is made up of natural and human sounds. Cultural and historic sounds, like the rhythm of a horse-drawn wagon, are components, too. Sounds definitely enhance a Yosemite National Park experience for visitors. Listening to water flow or wildlife vocalize can be degraded by inappropriate sounds or sound levels. It’s possible that increased noise may disrupt wildlife behavior, particularly in mating, locating prey and other complex communication methods. For these reasons, the unique enjoyment of sounds in a park setting makes the soundscape worthy of protection.

Dark Night Sky: A natural lightscape, such as a dark night sky, is an environment that has not been disturbed by light or air pollution. In Yosemite, dark night skies have natural, cultural and scenic importance. Animals, especially nocturnal ones, depend on darkness to hunt, conceal their location, navigate and reproduce. Plants can be affected by artificial light because it disrupts their natural cycles. Many Yosemite visitors come to experience a worldwide vanishing resource. To study the topic, the National Park Service devised a system to measure sky brightness, and even remote parks like Yosemite face stray light pollution, particularly from the San Joaquin Valley.

Scenic Vistas: Looking out from Yosemite’s Inspiration Point offers a breath-taking scenic view. These views, seen by explorers like James Mason Hutchings and John Muir, are part of the history that inspired the protection of the park in the late 1800s. Restoration projects prevent unnatural growth—vegetation encroachment—in open areas to retain the historic views for which Yosemite is known. Yosemite scientists aim to restore the park’s historic scenic vistas using sound cultural and ecological practices and processes. A new multi-year project will identify historic and current park vistas using previous vista studies, historical records, GIS data and site visits. The park staff’s goal is to incorporate viewshed and vista management into applicable planning efforts.

Fire: Fire has many faces.  It is a force that some people are fearful of, and others are inspired by. It is a phenomenon that is both fascinating and dangerous. In Yosemite, it is something that we manage carefully and continue to learn more about. Yosemite's has an extensive fire history. Historically, fire was often seen as a negative force, but in recent years it has been realized that the benefits of fire in forests are numerous. Yosemite's fire management program is designed to protect life, property, and natural and cultural resources, while ensuring the continuation of fire as a natural process. Fire managers use three tools to mimic fire's natural function in the ecosystem: prescribed fire, mechanical thinning, and wildland fire use. While visiting Yosemite, you may see evidence of any of these practices.

Weather:  Yosemite National Park is a changing environment where weather can vary by the minute, with increased chances of change at higher elevations. Temperatures at the 4,000-foot Yosemite Valley rise to more than 100 in the summer with lows in the single digits and nearly 30 inches of snowfall on average. All this variability produces a lot of lightening, a beneficial element in the Sierra Nevada fire-dependent environment. Park statistics show nearly 1,800 lightening-caused fires in Yosemite since 1972 and a third of those were managed by park staff. Overall, the changing weather only adds to the enjoyment of Yosemite, luring visitors during all four seasons.

View a list of the park's fact sheets.