The Swedish 16-year-old, who was recently Time magazine’s youngest ever Person of the Year for inspiring a global movement to fight the climate crisis, made the comment while addressing a Fridays For Future protest in the northern city of Turin.
In English, the phrase is associated with execution by firing squad, but Thunberg said it had a different meaning in her native language – simply, to hold someone accountable.
“That’s what happens when you improvise speeches in a second language,” she added on Saturday.
Thunberg was speaking in Turin after attending the UN climate summit COP25 in the Spanish capital of Madrid.
She said she feared the summit alone would not lead to adequate climate action, and that activists should continue to take world leaders to task.
“World leaders are still trying to run away from their responsibilities, but we have to make sure they cannot do that,” she said.
“We will make sure that we put them against the wall, and they will have to do their job to protect our futures.”
Thunberg later took to Twitter to apologise for the comment.
“Of course I apologise if anyone misunderstood this. I cannot enough express the fact that I – as well as the entire school strike movement – are against any possible form of violence. It goes without saying but I say it anyway.”
While speaking in Turin, Thunberg also urged the city’s youth to make 2020 a “year of action”.
“In less than three weeks we will move into a new decade and... I cannot say enough how important this decade will be,” she said.
“This is a decade that will define our future.”
After a months-long journey through North America to raise awareness of environmental issues, Thunberg returned to Europe earlier this month after crossing the Atlantic via catamaran.
The teenager does not fly due to the heavy carbon footprint of air travel.
In naming her Person of the Year, Time magazine wrote that Thunberg “has offered a moral clarion call to those who are willing to act, and hurled shame on those who are not”.
