A Nasa scientist who went viral over his tearful protest on the climate crisis has told The Independent that his activism comes from a sense of desperation to “find something that actually has an impact and moves the needle”.

Peter Kalmus was among a group of scientists arrested last week after they chained themselves to a JPMorgan Chase building in Los Angeles in protest of the bank’s financing of fossil fuels.

A video showed the scientist breaking down in tears and pleading with people to listen to urgent climate warnings. “We’re going to lose everything,” he said. “And we’re not joking, we’re not lying, we’re not exaggerating.”

Dr Kalmus, who spoke to The Independent on his own behalf and not as an employee of Nasa, is also an author and has more than 220,000 followers on Twitter. But despite his significant platform to speak on the climate crisis, he described it as an “echo chamber”.

“I think it’s critical for the message of climate urgency to make its way out into the mainstream,” he said, in a phone interview.