Teenage activist Greta Thunberg has given an angry and emotional speech at the United Nations Climate Action Summit in New York.

The 16-year-old admonished world leaders saying “you have stolen my dreams and my childhood” by not acting on climate change.

The Swedish girl held back tears as she delivered the speech to the UN General Assembly, made up of more than 50 global leaders.

“You all come to us young people for hope. How dare you?

You are failing us. But young people are starting to understand your betrayal.

The eyes of all future generations are upon you, and if you choose to fail us, I say, we will never forgive you.

We will not let you get away with this.”

Australian Prime Minister Scott Morrison has chosen not to attend the summit in New York but has mentioned the environment during a keynote speech in Chicago.

US President Donald Trump has also chosen not to take part in formal discussions but has made a brief appearance.

Image: Getty/Stephanie Keith