Swedish climate campaigner Greta Thunberg said Monday that young people like her have had to grow up "too quickly" to resolve a climate crisis caused by previous generations.

Denouncing inaction by politicians on climate change, Thunberg made her remarks just days ahead of the fifth anniversary of a global youth climate protest that drew over a million participants.

On Monday, she sat on the steps of Sweden's parliament, blocking the main entrance in a protest with around 10 other youth activists, holding a banner reading "Climate Justice Now".

"We are way too many young people who have had to grow up in the climate movement and who have had to grow up way too quickly, to take the responsibility to try to clean up after the older generations," Thunberg told AFP.

"The Swedish government as well as all other governments in the world are not treating the climate crisis like a crisis at all."

"They are still letting short-term economic profits be prioritised over human lives and the planet," she said, adding that she and her fellow activists "feel a bit like broken records, we have been repeating the same message over and over again".

News agency TT reported that politicians were still able to enter parliament through side entrances.

When Thunberg started sitting outside the Swedish parliament in August 2018 with her "School Strike for the Climate" sign, she was an anonymous teenager in a world she saw as dying in silence.

Five years later, Thunberg's "Fridays for Future" movement and its subsequent global marches had had a global impact, political science researcher Joost de Moor told AFP in October.

"It has raised awareness for the issue," he said.

It has also "contributed to the increased legitimacy of pro-climate policy-making, which has in turn made it easier for willing politicians to act on the issue", he said, citing as an example Frans Timmermans, the former EU climate commissioner responsible for the Green Deal currently being debated in the bloc.

Despite this, and "as Greta Thunberg has said herself many times... climate policy making continues to fall far behind what climate scientists say is necessary", de Moor said.

A report by the European Environment Agency (EEA) on Monday warned of "catastrophic" consequences if Europe failed to take urgent action to adapt to risks posed by climate change.