Case Study: Sequoia & Kings Canyon National Parks

These twin parks have long served as icons of California’s unique Sierra ecosystem. Encompassing 1,352 square miles combined (nearly as big as Rhode Island), these two parks are jointly administered by the National Park Service and welcome over 1 million visitors per year. With stunning mountains, caverns, forests, foothills and 2,000 plus-year-old sequoias towering overhead, the Land of Giants might seem invincible. In truth, these majestic parks, and the plants and wildlife which rely on them, face the unique and devastating consequences from human-caused air pollution and climate change.

Sequoia National Park is home to Mount Whitney, the highest mountain in the Lower 48, and General Sherman, a 275-foot tall and 36-foot-wide giant sequoia – the largest tree on earth by volume. Just south of Sequoia, visitors can hike the deepest canyons in the United States and witness the graceful peaks of the southern Sierra Crest at Kings Canyon National Park. The stunning vistas and diverse ecosystems of the parks face huge risks as air pollution harms visitors’ and employees’ health, vegetation, wildlife, and frequently obscures the views. Poor visibility and dirty air are a regular occurrence in these parks, a direct result of pollution from industrial sources like oil and gas, agricultural operations, and cars and trucks throughout the state. Poor air quality hurts human health and hinders the ability to enjoy these world-famous parks. Today, Sequoia & Kings Canyon also grapple with the dual challenges of air pollution and the increasing threats from climate change.

Our Polluted Parks 2024 report finds that Sequoia and Kings Canyon are, among all national parks, at the highest risk from air pollution – they both have significant levels of concerns in all three air categories: Unhealthy Air, Hazy Skies and Harm to Nature. In terms of climate threats to parks, these two are particularly vulnerable to both drought and wildfire.

When ozone concentrations reach unhealthy levels, they pose serious threats, affecting not only people, but also the health of nature and park ecosystems. Sequoia trees, with their stature and longevity, are especially vulnerable to the detrimental effects of ozone, which can compromise the overall vitality of the forest by hindering growth and harming mature trees. Our report’s findings under Unhealthy Air – drawn from data around ground-level ozone – underscore the importance of curbing this pollutant in Sequoia & Kings Canyon.

As climate change accelerates, Sequoia & Kings Canyon National Parks face shifts in temperature and drought, contributing to a cascade of environmental changes. Beyond consequences for water quality and habitat, Sequoia & Kings Canyon face unprecedented, severe wildfires, threatening thousand-year-old trees – many that have already been lost to recent fires – as well as nearby communities. These intertwined issues demand prompt, comprehensive and place-based action to protect the natural wonders of Sequoia & Kings Canyon.

For many years, NPCA has worked directly with a large coalition of environmental and public health groups to clean up some of the nation’s dirtiest air in the neighboring San Joaquin Valley to help benefit local communities and adjacent national parks. NPCA has helped oversee local Clean Air Act planning and enforcement advocacy to seek reductions in fine particulate matter and ozone pollution from sources like cars, trucks, and oil and gas operations. In fact, NPCA’s action resulted in a major court victory in 2018, holding state agencies accountable to regulating air pollution throughout Yosemite, Sequoia and Kings Canyon. In addition, NPCA leads California regional haze advocacy seeking to improve visibility across the Golden State. We will continue our advocacy and collaborative efforts with the aim of delivering cleaner air and a healthy climate to these treasured national parks and all who live around them and enjoy them.