Nature (Season 35) – Yosemite

Air date: 03/29/2017

THIRTEEN’s Nature Explores the Impact

Of Climate Change on the Ecosystem  of Yosemite

Wednesday, March 29, 2017 on PBS

Kevin Kline narrates an up-close look at this great wilderness

The Sierra Nevada, a mountain range running about 400 miles along the eastern side of California and stretches into Nevada, is home to three national parks:  Sequoia, Kings Canyon and Yosemite. This is a land of giants, whether speaking of trees soaring to nearly 300 feet, or massive stone monoliths far taller than any skyscraper. But the force that has given rise to the earth’s largest living trees and carved out the iconic natural landmarks of the Sierras is water.  The role that water has played in the creation and evolution of Yosemite Valley cannot be overstated – feeding its numerous wild rivers and countless waterfalls, and making life in this stone wilderness possible. The second force, crucial to the Giant sequoias’ ability to reproduce, is fire. It is the delicate balance of these two elements, water and fire, that is vital to the continued existence of the wildlife and trees that inhabit the Sierras.

Despite the recent heavy rains and snowfall, scientists are finding that water is scarcer and the threat of fire is more likely as the area continues to experience rising temperatures upsetting that important balance. Geologists, ecologists, researchers and adventurers investigate how the changing climate is affecting one of America’s greatest wildernesses when Yosemite airs Wednesday, March 29, 2017 at 8 p.m. (ET) on PBS (check local listings). After broadcast, the episode will be available for limited online streaming at

Shot in 4K, the film opens at dawn in Yosemite Valley where hang glider pilots like Jeff Shapiro get ready to launch their aircraft at Glacier Point. Once aloft, the valley’s famous glacier-shaped granite landmarks such as El Capitan, Half Dome and Sentinel Rock come into view. The scenic valley can also boast of having the tallest waterfall in North America, Yosemite Falls, as well as Bridalveil and Horsetail.

Water has long been synonymous with the Sierras as more than 30 percent of California’s fresh water comes from the area’s snowfall. Filmmaker Joseph Pontecorvo follows members of the California Cooperative Snow Survey Program in the high peaks as they determine the amount of water in the year’s snowpack. They find an improvement over recent drier years but confirm that the water content is still far from normal, and with rising temperatures, the snowpack will continue to shrink over the long term.

In Sequoia National Park, U.S. Geological Survey’s Nate Stephenson, a forest ecologist, explains how fire and snow create the necessary conditions to produce Giant sequoia seedlings that have a potential life span of more than 3,000 years. Although hardy trees, Stephenson is noticing they are losing foliage as the atmosphere pulls more water out of the leaves due to increased temperatures. Researcher Anthony Ambrose and his team are shown monitoring the Giant sequoias’ water supply by taking leaf samples from both the canopy and base of the trees. They are finding greater stress levels than ever before, but given the resilience of these trees, Ambrose hopes to determine how much stress they can withstand.

Yosemite also focuses on the wildlife that make their home in these protected parks. Peregrine falcons are back once again to nest on mountain cliffs, and there has been an effort underway to stage the return of the Sierra Nevada bighorn sheep. The film describes how the California Gold Rush resulted in severely decreasing the bighorn population in the mid-1800’s and how the Sierra Bighorn Sheep Recovery Program is working to restore these icons to the high country.

While the Sierras experience more dramatic shifts of weather, from flash floods to extreme drought, only a good snowmelt provides photographers with a once a year chance to capture a remarkable sight at sunset:  if enough water cascades over Horsetail Fall as the sun hits it, the waterfall glows like a ribbon of red orange fire. The power of water continues to exert its influence in Yosemite.

Nature is a production of THIRTEEN PRODUCTIONS LLC for WNET. For Nature, Fred Kaufman is executive producer. Yosemite is a production of Pontecorvo Productions and THIRTEEN Productions LLC for WNET.

Nature pioneered a television genre that is now widely emulated in the broadcast industry.  Throughout its history, Nature has brought the natural world to millions of viewers.  The series has been consistently among the most-watched primetime series on public television.

Nature has won more than 700 honors from the television industry, the international wildlife film communities and environmental organizations, including 17 Emmys and three Peabodys. The series received two of wildlife film industry’s highest honors: the Christopher Parsons Outstanding Achievement Award given by the Wildscreen Festival and the Grand Teton Award given by the Jackson Hole Wildlife Film Festival. The International Wildlife Film Festival honored Nature executive producer Fred Kaufman with its Lifetime Achievement Award for Media. is the award-winning web companion to Nature, featuring streaming episodes, filmmaker interviews, teacher’s guides and more.

Support for this Nature program was made possible in part by the Arnhold Family in memory of Clarisse Arnhold, Sue and Edgar Wachenheim III, the Kate W. Cassidy Foundation, the Lillian Goldman Charitable Trust, the Filomen M. D’Agostino Foundation, Rosalind P. Walter, Sandra Atlas Bass, Susan R. Malloy, Jennifer M. Combs, Timon J. Malloy and the Sun Hill Foundation, the Arlene and Milton D. Berkman Philanthropic Fund, by the Corporation for Public Broadcasting, and by the nation’s public television stations.



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Yosemite Falls reflecting in the Merced River in the heart of Yosemite Valley. The Merced River is one of three major river systems that feeds California’s Central Valley. Yosemite Valley, California. Nimmida Pontecorvo/© THIRTEEN Productions LLC

Yosemite is home to countless waterfalls, including the tallest in North America, Yosemite Falls. Yosemite Valley, California. Nimmida Pontecorvo/© THIRTEEN Productions LLC

A wildfire just outside of Yosemite National Park. As the temperatures rise, due to climate change, the frequency and intensity of wildfires grows. Bass Lake, California. Joseph Pontecorvo/©THIRTEEN Productions LLC

The Giant Forest in Winter. Sequoia National Park is home to the largest trees on Earth. These giants depend upon water from the Sierra’s snowpack in order to survive. Sequoia and Kings Canyon National Park, California. Nimmida Pontecorvo/©THIRTEEN Productions LLC

The first snow of winter coats El Capitan and the surrounding mountains. It was the power of water that carved out Yosemite Valley, and 2,000-foot glaciers polished the granite into their iconic shapes. Yosemite National Park, California. Joseph Pontecorvo/ ©THIRTEEN Productions LLC

Sentinel Rock is one of the many iconic granite formations that surround Yosemite Valley. Yosemite National Park, California. Nimmida Pontecorvo/© THIRTEEN Productions LLC

Yosemite Valley experiences a blanket of snow after years of drought. But the future may not be so wet. If warming trends continue, the Sierra Nevada could lose up to 80% of its snowpack by the end of this century. Yosemite National Park, California. Joseph Pontecorvo/© THIRTEEN Productions LLC

Geologist Roger Putnam on an assent of El Capitan. He has made 41 ascents of El Capitan, the fastest took him under 6 hours. Yosemite Valley, California. Jonathan Byers/© THIRTEEN Productions LLC

Pikas are poor thermal regulators and highly sensitive to changes in temperature. They are considered the “canary in the coal mine” of climate change. Eastern Sierra Nevada, California. Joseph Pontecorvo/© THIRTEEN Productions LLC

Light from the full moon illuminates Half Dome. Winter in Yosemite is a magical time and even more remarkable by the light of the moon. Yosemite National Park, California. Joseph Pontecorvo/© THIRTEEN Productions LLC

Researchers Wendy Baxter and Anthony Ambrose measure a giant sequoia. The team monitors the health of these giants to gage the impact of climate change. Whitaker’s Forest, California. Nimmida Pontecorvo/© THIRTEEN Productions LLC

"Yosemite" Filmmaker Joseph Pontecorvo. Nimmida Pontecorvo/© THIRTEEN Productions LLC