[dropcap]I[/dropcap]n Hieronymus Bosch’s triptych “The Garden of Earthly Delights”, the painter depicts humanity’s lust for overindulgence and the consequences of consumption. In its three panels, Bosch illustrates both paradise and its oppositional counterpart — a monstrous landscape bred from life’s tribulations.

In a voiceover, Leonardo DiCaprio expresses how it hung over his crib as a baby and how he ultimately came to realize its meaning.

It is a rather appropriate allegory to bookend his new documentary on climate change, Before the Flood, which held its world premiere at the Princess of Wales Theatre. The film follows DiCaprio in his first motion picture appearance following The Revenant, in which his portrayal in Alejandro González Iñárritu’s tale of survival earned him an Academy Award.

Much like the historical figure Hugh Glass, DiCaprio is on a mission; his documentary serves as a call to action. Adopting his new position as the United Nations Ambassador of Peace, DiCaprio is followed by The Cove director Fisher Stevens, as he travels to multiple countries to deliver the unnerving and indisputable facts of climate change.

The Academy Award winner expresses his pessimism throughout the course of the film, especially when he engages in thought-provoking discussions with prominent global figures such as Pope Francis and President Barack Obama, as well as scientists, astronauts, and farmers.

At one point in Before the Flood, Iñárritu explains having to relocate filming locations for The Revenant from Alberta to Argentina to accommodate for the availability of snow. From the tar sands in Alberta to constant flooding in Miami, smog-laden Beijing, and melting ice caps in the South Pole, there’s nowhere Leo won’t go.

His ever-growing concern for our species and persistence to get the word out results in a powerful plea for change. Whether it be from less palm oil or beef consumption, to voting to empower political leaders who can push for a fuel tax, a change must occur.

Much like Agnès Varda’s The Gleaners and I or Al Gore’s An Inconvenient Truth, the film is an important work of cinema that demands our attention. Before the Flood makes the delivery of the facts of climate change more hard-hitting by harnessing musical contributions from Trent Reznor, Atticus Ross, and Mogwai.

By providing the scientific community a voice, DiCaprio makes Before the Flood more palatable for the general public through the medium of film. The actor himself made an appearance at the screening, highlighting to the audience the importance of the whole truth.

In his pre-screening speech, DiCaprio lamented, “We are truly at a turning point in history, and this issue really depends on the education of the public, and the evolution of our species to combat what is the largest crisis we’ve ever faced.”

National Geographic will air the documentary in 171 countries and in 45 languages on October 30.