"The extinction rate is up to six times faster than what is considered normal, with up to 200 species becoming extinct every single day," she said. "Erosion of fertile topsoil, deforestation of the rainforest, toxic air pollution, loss of insects and wildlife, acidification of our oceans — these are all disastrous trends."

Here are some other highlights of her talk.

1. Brexit: Thunberg faulted European leaders for spending more time addressing the UK's departure from the EU than the climate crisis, saying that they were not treating the latter like the emergency it is.

"If our house was falling apart, you wouldn't hold three emergency Brexit summits and no emergency summit regarding the breakdown of the climate and the environment," she said.

During the same section, Thunberg argued that the EU continued to celebrate milestones — such as Ireland's possible divestment from fossil fuels — that fell behind the urgency of the moment.

"It's 30 years too late for that kind of celebration," she said.

2. EU Elections: The next elections for members of European Parliament (MEPs) will take place in late May. Thunberg addressed this in her talk, mentioning that she and other young people worried about their futures cannot vote.

"You need to listen to us, we who cannot vote. You need to vote for us, for your children and grandchildren. What we are doing now, can soon no longer be undone. In this election, you vote for the future living conditions of humankind," she said.

3. Notre Dame: Thunberg made two references to the fire that caused the spire of the historic Paris cathedral to collapse Monday.

"Yesterday, the world watched with despair and enormous sorrow how the Notre Dame burned in Paris. Some buildings are more than just buildings. But the Notre Dame will be rebuilt. I hope that its foundations are strong. I hope that our foundations are even stronger, but I fear they are not," she said at the beginning of her speech.

She referenced the church again towards the end, saying that the vision and courage required to make the necessary changes to combat climate change would require "cathedral thinking."

You can watch her whole speech here:

This isn't the first time Thunberg has urged world leaders to act on climate change. She delivered powerful speeches at the COP24 talks in Katowice, Poland in December 2018 and at Davos this year.

MEPs decided not to invite her to address the parliament's debating chamber in February after it was proposed by the Greens. Liberal and center-right MEPs argued against it on the grounds that the spot should be reserved for politicians or officials and that a child would be too vulnerable in that environment, The Guardian reported.

MEPs responded well to Tuesday's speech, giving her a 30 second standing ovation. Individual members also thanked her after the speech, as The Parliament Magazine reported.

"I speak as a mother of two and I feel the same as you, Greta," Maltese deputy Miriam Dali said. "But when it comes to the crunch we, here, often end up backing down from our climate ambitions."

Dutch Green MEP Bas Eickhout also thanked her.

"I hope we all remember this day when we speak of an end to the world in July when we vote on new EC [European Commission] president and whether we really want to change our policies, phase out coal and make aviation pay," he said.