16-year-old environment activist Greta Thunberg gave the U.N. a stern talking to Monday at the Climate Summit, almost in tears, saying in her impassioned speech:

‘I shouldn’t be up here. I should be back in school on the other side of the ocean. Yet you all come to us for hope. How dare you. You have stolen my dreams and my childhood with your empty words.’

Thunberg scowls at Trump.

When Trump — who wasn’t scheduled to appear — tried to upstage her, Thunberg glared at him in a photo that is now going viral.

Watch the pint-sized activist in action.