Greta Thunberg says school strike for climate movement only became so big because it 'pissed off' nay-sayers

Climate activism has benefitted from the anger of its critics, says Greta Thunberg, adding the 'school strike for climate' movement would never have become so big if not for people getting "pissed off" at the idea.

In an interview with the BBC, the teenager suggested the fury of climate change deniers can be a helpful tool for generating interest in protests over inaction on global warming.

The comments came ahead of COP26 - the United Nations' Climate Change Conference - which is being held in Glasgow, Scotland over the next fortnight.

"To make clear, as long as no-one gets hurt, then I think sometimes you need to anger some people," she told BBC journalist Andrew Marr.

"Like, for instance, the school strike movement would never have become so big if there wasn't friction, if some people didn't get pissed off."

The Swede, who at age 18 is one of the world's most prominent climate activists, told Marr she still believes it is "possible in theory" to prevent temperatures rising more than 1.5C above pre-industrial levels.

The 1.5C cap set out in an Intergovernmental Panel on Climate Change (IPCC) report earlier this year would help the planet avoid some devastating climate impacts, such as deadly heatwaves and storms.

Many experts believe keeping temperature rises below this level is an unrealistic target, but Thunberg says it's "up to us if we want that to happen".

She called on people in countries where the right to protest was protected to stand up for the cause, explaining that she'd spoken to climate activists doing it much tougher in countries like China, which don't share the same freedoms.

"It makes you just feel so grateful that we are actually able to protest and that just puts more responsibility on us who actually have the right to protest, to use that right," she said.

"Not just for our sake but for everyone's sake, especially for their sake to help them as well."

The IPCC report released earlier this year, a culmination of years of research from climate scientists from around the world, paints a horrifying picture of what humanity is doing to the climate.

It found 50-year heatwaves could become almost annual events and suggests a potential sea level rise of 15m in the next couple of hundred years, and 22m in the next two millennia if emissions aren't reined in. 

On Sunday, the Government announced a new Nationally Determined Contribution (NDC) and will reduce greenhouse gas emissions by 50 percent by 2030.