Mark Ruffalo is angry. “Donald Trump is public enemy number one,” says the man who plays Hulk in the Avengers films, leaning forward in his chair. “Everything that comes out of his mouth is a lie. This dude is standing in the way of anything significant happening in the world as far as climate change is concerned. It’s f***ing terrifying and it keeps me up at night. Most people don’t realise what’s coming. Countries are freaking out about Syrians coming, a few thousand Syrians. We are approaching mass extinctions, food systems failing, hundreds of millions of displaced people looking for places that are hospitable.” He pauses, breathes. “In my country, half of the political system doesn’t believe in [climate change], in science. I’m inviting the rest of the world to get involved in our next election, because the fate of the world is in the f***ing balance. And you can print that.”