Climate activist Greta Thunberg has brushed off criticism and mockery from US treasury secretary Steven Mnuchin, saying that his comments have “of course no effect” on her and fellow campaigners.

The Swedish 17-year-old acknowledged such young activists “are being criticised all the time”.

“We cannot care about those kinds of things,” she said, insisting that her priority was drawing attention and action to concerns about global warming.

“The situation is not being treated like the crisis it is,” she added.

The teenager, who was selected as Time’s Person of the Year for 2019, has returned to the World Economic Forum’s annual summit in Davos, Switzerland, this week to press her call for businesses, world leaders and others to take action in the face of scientific evidence showing that temperatures on Earth are rising.

She spoke to reporters along with four other young climate activists, before they set off through the streets of Davos for the latest weekly Fridays for Future campaign that she launched.

Climate activists Isabelle Axelsson, Loukina Tille, Vanessa Nakate, Greta Thunberg and Luisa Neubaue, from left, at a news conference in Davos, Switzerland
Climate activists Isabelle Axelsson, Loukina Tille, Vanessa Nakate, Greta Thunberg and Luisa Neubauer in Davos (Markus Schreiber/AP)

At the news conference, Greta sought to share the spotlight, deferring to her fellow activists: Vanessa Nakate, from Uganda, Loukina Tille, from Switzerland, Luisa Neubauer, from Germany, and Isabelle Axelsson, from Sweden.

A day earlier, Mr Mnuchin dismissed the teenager’s suggestion that governments and companies need to cut back dramatically on their use of fossil fuels with a condescending barb.

“Is she the chief economist? Who is she? I’m confused,” he said.

US treasury secretary Steven Mnuchin
US treasury secretary Steven Mnuchin said his comments were ‘a joke’ (Steve Helber/AP)

Then following a brief pause, he said it was “a joke”.

“After she goes and studies economics in college, she can come back and explain that to us,” he concluded.