Youth Climate Activist Greta Thunberg arrived in New York ahead of a United Nations Summit she will attend at the invitation of Secretary-General António Guterres. “The determination and perseverance shown during your journey should embolden all of us taking part in next month’s #ClimateAction Summit,” he said in a tweet welcoming her. “We must deliver on the demands of people around the world and address the global climate crisis.”

Greta said the climate crisis is the biggest humanity has ever faced. “If we don’t manage to work together to cooperate and to work together despite our differences then we will fail,” she warned. “So we need to stand together and support each other and to take action because otherwise it might be too late. Let’s not wait any longer; let’s do it now.”

The Summit will bring together governments, the private sector, civil society, local authorities and other international organizations to develop ambitious solutions to the climate crisis.