Documentary explores how climate change is impacting Yosemite
PBS' "Nature" series will premiere "Yosemite," a sublime look at one of our nation's most stunning national parks. It's also a sobering one, as the park's ecosystem is threatened by climate change. Award-winning nature filmmaker Joseph Pontecorvo, who produced, wrote and served as a cinematographer, joins "CBS This Morning: Saturday" to discuss the filming process and the park's future.