Leonardo DiCaprio in Before the Flood: Our Last Best Hope

Leonardo DiCaprio's Before the Flood, a documentary exploring this critical historic moment when we can actually do something about climate change premiered this week at the United Nations. Most compelling about this National Geographic film is its focus on the personal. Screened at the General Assembly Ecosoc Chamber with luminaries present, the film opens with Leo remembering a painting by Hieronymus Bosch from his childhood, "The Garden of Earthly Delights," a triptych that goes from rich, saturated, edenic visions to bleak, scorched landscape. The focus on Leo's journey is an effective way for viewers to grasp the immense problem of global warming.

Directed by his pal Fisher Stevens, Before the Flood limns Leo's voyage as an environmental activist--he is officially the UN's Messenger of Peace for Climate Change-- and features interviews with President Obama, Pope Francis, UN Secretary General Ban Ki-Moon and Secretary of State John Kerry who worked on the vital Paris Agreement ratified by nearly 200 countries committed to trying low carbon energy solutions.

Nature and art, Leo's passions, inform his political views. Again from DiCaprio's experience: In Canada for the filming of The Revenant, he saw firsthand the set turn to water, a result of warming. Interviewed in the film, director Alejandro Innarritu had to move the production to the tip of South America, a last repository of ample snow. Traveling as official messenger, Leo pats an elephant's trunk in Indonesia, visits endangered rain forests, and plays with chimpanzees, a reminder of a fragile world. An impressive spokesperson, Piers Sellers, a meteorologist and NASA astronaut, explains the science. After the screening, Sellers, Stevens, and DiCaprio sat for a Q&A with John Kerry who left everyone with a feeling of hope, and information about a carbon tax now in place.

Guests moved on to an outdoor balcony the size of a soccer field with extraordinary city views. Leo's very proud dad, George, a Frank Zappa lookalike, snapped photos of the Chrysler Building wrapped in fog. Paul Haggis, Lawrence Wright, Russell Simmons, John Leguizamo, Trudie Styler, Edward Norton, and Mark Ruffalo mingled. David O. Russell ran into an old pal, painter Walton Ford whose work is collected by Leonardo DiCaprio. Leo posed for selfies with fans as servers shucked oysters dumping shells into buckets attached to their belts. Chuck Close zipped about in his customized wheelchair, a longtime friend. When asked whether Leo collected his work, Close said, "He did, but he's probably sold it."

A version of this post also appears on Gossip Central.