Salt and Fire actor Gael García Bernal on working with Werner Herzog

Actor Gael García Bernal – whose latest film, Salt and Fire, focuses on the disastrous ecological consequences of abusing the environment – tells us the chance to work with veteran director Werner Herzog was a dream come true.

Actor Gael García Bernal. Greg Doherty / Getty Images

Given their respective ­filmographies, it is a ­little surprising that Mexican actor Gael García Bernal and German ­director Werner Herzog have not worked together before now.

After all, they both have a long list of socially conscious ­movies under their belts. Herzog has made a plethora of documentaries that look at the effect ­humans have had on the ­environment. Bernal has co-­directed four short films, Los Invisibles, about migrants from Central America in Mexico, and founded the Ambulante film festival, which specialises in showing political documentaries that might not otherwise get a release in Mexico.

In Herzog's latest film, Salt and Fire, Bernal plays a scientist who is part of a group invited to ­Bolivia by the United Nations to investigate rare geological formations in the Uyuni salt flats that are believed to be warning signs of an ecological disaster.

Collaborating with Herzog was a dream come true for Bernal, who discovered the work of the German director while he was studying acting at the Central School of Speech and Drama in London. Bernal struggled there as it was geared to actors ­working on stage speaking ­standardised English, so he often went to a repertory cinema instead of class.

“This was before the internet, so I would go into the cinema not knowing anything about what I was going to see,” he says. “I remember saying to my ­classmates, ‘There is a great director called Herzog’, and I felt like I had discovered him.”

Salt and Fire is loosely based on Tom Bissell's short story, Aral, which reveals how the ­misguided irrigation policies of the Soviet Union destroyed Uzbekistan's Aral Sea. The film transplants the action to South America, and adds a kidnap to the dramatic mix. But for the most part, the film is best ­described as "otherworldly". Herzog says Salt and Fire is "like a daydream that doesn't follow the rules of cinema".

Not fitting into the rules of cinema is something that Herzog specialises in. His films are often a hybrid of fact and fiction, and the end result is what Herzog calls an “ecstatic truth”.

“Sometimes facts so exceed our expectations – have such an unusual, bizarre power – that they seem unbelievable,” the director says. “But through cinema and art it’s possible to discover a deeper meaning, a higher truth, and that is ecstatic truth, which is mysterious.”

Bernal will be 40 next year, but retains the boyish good looks and charm he displayed in Mexican films Amores Perros and Y tu Mamá También, which catapulted him to global superstardom at the turn of the millennium.

Since then, he has often been cast as a charmer, in films such as The Science of Sleep, so it is fun in Salt and Fire to see him play his scientist as somewhat sleazy. But Bernal does not view the role as a change in direction because he does not accept there is a ­typical Bernal performance.

“I don’t think I’ve had to break any boundary or stereotype,” he says. “The best way to break a taboo is not recognise it.

“For example I cannot play a typical Mexican, because I’m from Guadalajara and I know it’s different culturally from Mexico City, where I now live – so I know from my own experience that a typical Mexican does not exist.”

The influence Herzog has had on Bernal is perhaps most profound in the change in the actor’s reading habits.

“Recently I’ve started reading a lot of science, poetry and philosophical essays,” he says.

“I haven’t read a novel in two years – I get bored with novels now. I like going into myself or someone else.”

Looming large in the ­background of Salt and Fire is an impending environmental ­disaster, and Herzog sees the end of humanity as an ­inevitability.

“I’m convinced that our ­presence on this planet is not sustainable, so we will be extinct soon,” the director says.

“Human beings will be extinct because cockroaches have a ­better chance of survival.”

There are, he adds, so many things that could wipe out ­humans. “Microbes are really after us, or a meteor or a super-­volcano,” he says. “The last ­really big volcanic explosion took place in New ­Zealand and nearly wiped out everyone. It doesn’t make me nervous that we’ll become extinct, it doesn’t frighten me at all.”