“We Are Transforming These Mountains in a Way Humans Have Never Seen”: The Future of the Sierra Nevada, John Muir’s Range of Light

John Muir called the Sierra Nevada the “Range of Light” in his 1894 book, The Mountains of California, writing about the exceptional quality of light there, calling it “the most divinely beautiful of all the mountain-chains I have ever seen.”

I can’t top his poetic description, but for me, the contrast of the glowing beige peaks, indigo sky, emerald lakes, and green forests is unique in my Triple Crown and lifetime of hiking. I have hiked the John Muir Trail twice and am going back again this summer. This trip may be the last time for me, as my lifetime hiking window is closing. And I intend to revel in it.

I wrote about climate change on the Colorado Trail in my book, Colorado Trail in Crisis, after witnessing extensive forest mortality along the trail when I hiked it in 2020 – 21. I also wrote about climate change in the Sierra in the 2024 Fall/Winter PCT Communicator. The 2012 – 2016 drought (during which time I hiked the PCT) was the worst in California history and perhaps in the last 1,200 years based on tree ring and sediment dating.

As an environmental scientist, I see big changes in store for Muir’s Range of Light. If you haven’t hiked the Sierra or visited Yosemite or Sequoia and Kings Canyon National Parks, go now if you can. Take people you love. These treasured mountains are a microcosm of the great global changes that will occur in our own lifetimes. What does the future hold for the Sierra?

The Range of Light

Then it seemed to me The Sierra should be called not the Nevada, or Snowy Range, but the Range of Light. And after ten years spent in the heart of it, rejoicing and wondering, bathing in its glorious floods of light, seeing the sunbursts of morning among the icy peaks, the noonday radiance on the trees and rocks and snow, the flush of the alpenglow, and a thousand dashing waterfalls with their marvelous abundance of irised spray, it still seems to me above all others the Range of Light, the most divinely beautiful of all the mountain-chains I have ever seen.” – John Muir, The Mountains of California, 1894

The Sierra is unique for its rich biodiversity and natural beauty. Despite their proximity to population centers, these mountains are largely protected from development. Yosemite and Sequoia-Kings Canyon National Parks and several wilderness areas protect the backcountry. Few roads cross the high Sierra.

The range stretches about 400 miles through California, from Tehachapi Pass in the south to Fredonyer Pass (near Chester) in the north. Though only 50 to 80 miles wide, its great height and proximity to the Pacific Ocean enable it to trap heavy snowfall in the winter via occasional atmospheric rivers. Summers are mostly sunny and dry, ideal for hiking and backpacking.

The mystique of John Muir’s writings pervades many backpackers’ souls: From his book, Our National Parks, 1901:

“Climb the mountains and get their good tidings. Nature’s peace will flow into you as sunshine flows into trees. The winds will blow their own freshness into you, and the storms their energy, while cares will drop away from you like the leaves of Autumn.” — John Muir, Our National Parks, 1901

These mountains have stood for 20 – 40 million years. Many of the Sierra’s iconic peaks and valleys, including the beautiful Yosemite and now-submerged Hetch-Hetchy valleys, were carved by the glaciers that covered much of the range around 3 million years ago.

There are still glaciers in the Sierra today. They formed much more recently, during the Little Ice Age, and may have maxed out in 1872 when Muir studied them.

Now, 90% are gone.

Thinking like a mountain: why ask the question about the future?

“Thinking like a mountain” is a term coined by conservation luminary Aldo Leopold in his book A Sand County Almanac. Leopold discusses the thought process as a holistic view on where one stands in the entire ecosystem. To think like a mountain means to have a complete appreciation for the profound interconnectedness of the elements in the ecosystems and our role within them.

What is the future of the Sierra? I ask the question while trying to think like a mountain. Yes, it is pure hubris to try to predict the future of a mountain range that is 40 million years old. Geologic time created the range with the uplifting, erosion, and glacial scouring.

So why even ask about the future? Because we are transforming these mountains in a way humans have never seen before. The more we educate ourselves, the greater our chances of preserving the transformative beauty and functioning ecosystems we know today.

Climate Change, Development Pressure, Overcrowding: Key Threats to the Sierra

In the Sierra, annual temperatures under the average greenhouse gas emission scenario are projected to increase 8 – 9°F by 2100. (Note: the average scenario is no longer applicable, especially with the world’s failure to meet Paris accord goals). Unfortunately for us all, the US has abandoned these goals for now.

This temperature change may seem small, but to ecosystems adapted to a stable climate of the last several thousand years, this will cause major changes in vegetation (via forest die-off and wildfire) and wildlife habitat. It will alter the hydrology of the landscape, creating earlier and larger spring runoff (up by as much as 400%) and worsening summer heat and drought. It will exacerbate wildfires and make small blazes into large mega-fires. Extreme fire weather days will increase by one- to two-thirds.

Development pressures, such as the (ultimately unsuccessful) bid to develop Mineral King Valley and water projects like the flooding of Hetch Hetchy Valley, will always try to capture treasured wilderness. Currently, the Forest Service is being told to increase the cut, and the Bureau of Land Management is being told to “drill baby drill.”

Tourists crowd the roads in the national parks, while hikers and backpackers crowd the trails such that permits are the norm and access lotteries are becoming common. Federal land managers are experiencing major funding and staffing cuts and are increasingly unable to balance crowd management with fighting wildfires, maintaining trails, and protecting resources.

What does it all mean?

What does climate change mean for backpackers, tourists, and skiers, for agriculture and cities? In all cases, water is at the heart of the story.

Sixty percent of all of California’s water supply comes from the Sierra. That water irrigates the great orchards and crops of the Central Valley, supports municipal water supplies, and nurtures the extensive wetlands of the San Francisco Bay area. Precious water is wasted when a big flush of spring runoff overwhelms reservoirs. Agriculture and cities depend on snowpack to gradually release water and maintain reservoirs.

Outdoor recreation is also at stake. Even if they make artificial snow, ski areas still depend on natural snowpack. Hikers, of course, are dramatically impacted by snowpack as well — it determines everything from on-trail water availability to when the hiking season starts and how bad the wildfires are likely to be.

With climate change, water runoff will occur much earlier, and flooding will be more severe. California will suffer even more drought, stimulating more water projects. These trends are already occurring.

What can your children expect when they tackle the fabled High Sierra trails? Of course, the mountains will be there with or without humans. Vegetation and wildlife will persist, although likely in unexpected ways. The glaciers will not.

In the near term, we will continue to see more drought, drier and hotter weather, and more forest mortality, wildfire, and smoke. Winter hikers in the Sierra will see more rain and rain-on-snow, and in general we will see less snow in the Sierra overall. 

The hiking season will start earlier as snowpack and dependable water sources dwindle. Hikers will have to adapt to the hazards of wildfire, smoke, and heat stress and be prepared to bail or flip to avoid them. Of course, there will always be more demands for roads and water projects in the backcountry. Even the protected parks and wilderness areas are subject to political whims.

What can you do?

What can you do now? Ultimately, what we can only really control is our own lives. Take steps to reduce your carbon footprint and conserve water. Educate your friend and community if you can. Be politically active.

Reduce your carbon footprint: Americans have among the highest carbon footprints in the world. You can take steps to reduce yours, such as by traveling by bus, train, or EV. I have even done this to get to and from the John Muir Trail. If you must fly, buy carbon credits — they are inexpensive and theoretically cancel out your flight’s carbon emissions.

If you have the means, certain home renovations can also go a long way toward reducing emissions: consider adding solar to your rooftop, replacing gas furnaces and hot water heaters with more efficient heat pumps, and adding insulation to your attic.

Conserve water: Water conservation is another key to preserving the Sierra and other beloved lands. The coming years will see water crises around the country and world — not just in California. Political showmanship aside, the president cannot just “turn the tap on.” Conserve water at home; xeriscape and use drip watering.

Be an example to others, on and off the trail: Educate your friends and community if you can; set an example for your family and hiking friends.

Of particular interest for hikers is to be selective in gear and support suppliers that practice sustainable projects on the ground and with their fabrics. Avoid toxic polyfluorinated alkyl substances (PFAS) in waterproofing. Reduce plastic consumption in all aspects of your life. Plastics and microplastics are fouling our waters and oceans, and even accumulating in wildlife and our own bodies. Again, use public transportation. Leave-no-trace ethics, permit restrictions, and campfire restrictions/bans are crucial to preserving the wilderness.

Advocate for public lands and conservation: Be politically active to protect public lands and reduce greenhouse gas emissions. Join and donate to your favorite conservation group, like the Pacific Crest Trail Association. Volunteer for work on the ground. Protest if you must. Hikers and conservationists must regain momentum lost in Washington.

We will leave a legacy to the Range of Light and future generations of backpackers; what will it be?