Greta speaks to massive crowd in New York City's Battery Park. Photo by Lucas Johnson/Reuters. Front photo by Adam Johansson

That stark photo of Greta Thunberg's solitary, obstinate, one-person climate strike was, astoundingly, a mere year ago. This week, roughly four million impassioned people in over 160 countries joined her in the largest ever climate strike - and possibly the largest mass protest - in order to declare, "Like the Sea, We Rise." Also: "Make America Greta Again," "Denial Is Not A Policy," "Did You Buy the Planet Dinner Before U Fucked It?" "I'm Sorry Is Not Enough," "If You Think the Economy Is More Important Than the Environment, Try Holding Your Breath While Counting Your Money," "I Was Hoping For A Cooler Death," and "Wake up Bozos." Many young people view this week's protests as "not a moment but a movement," gearing up for on-going climate actions even as they voice an existential fear of and uncertainty about a future they're not sure they'll live to see. In words and spirit, they reflect Greta's fierce call to leaders: "I want you to act as if the house is on fire, because it is.”

On their behalf, Greta's rhetoric in speeches -contained in her book "No One Is Too Small to Make A Difference"- is hard-core, a stern moralist. Tuesday, she told Democrats fawning over her and other young activists, "Please save your praise, we don’t want it...Don’t invite us here to tell us how inspiring we are without doing anything about it." In an eloquent, furious screed before Congress, she blasted "fairy tales" about "how we are going to fix everything...We need to wake up. It’s time to face the reality, the facts, the science." She has warned nay-sayers who feel threatened, "We have some very bad news for you: This is just the beginning. Change is coming - like it or not." And at last January's World Economic Forum, she mercilessly refuted global leaders who said she gave them hope. "I don't want your hope," she said. "I want you to panic. I want you to feel the fear I feel every day. I want you to act." Dear Greta, We're all good on the panic thanks. If you don't mind, we'll take the hope as well.

Getty photos

Sydney, Australia. Twitter photo

Exactly one year ago. Photo by Adam Johansson

South Africa. Photo by EPA

Getty photos

Video from Freiburg, Germany