The first African-American expedition to climb Denali, North America’s highest peak, is the subject of An American Ascent. The film is being screened Saturday, April 2, as part of the Princeton Environmental Film Festival at Princeton Public Library. Now in its tenth year, the festival features a line-up of more than 25 acclaimed films with filmmakers and other speakers presented over the course of 7 days. For a complete list of festival films, and updates on speakers, see princetonlibrary.org.