WATCH: Greta Thunberg releasing book on climate change

Teenage climate activist Greta Thunberg is releasing The Climate Book in the fall, in which she explores a “global overview of how the planet’s many crises connect.”

In a video posted to Instagram, Thunberg said, “To me, hope is not something that is given to you. It is something you have to earn, to create. It cannot be gained passively, through standing by and waiting for someone else to do something. Hope is taking action. It is stepping outside your comfort zone.”