What do you want your legacy to be? Many would agree that we want to leave the world a better place than we found it, particularly if we have grandchildren who will inherit it.

Today, news media are full of reports of the adventures of Greta Thunberg, a 16-year-old from Sweden who is trying her best to raise the world’s awareness of the threat of climate change. A year ago, she took time off from school to demonstrate outside the Swedish parliament, holding up a sign calling for action to deal with climate change. Her demonstration attracted media attention and led to numerous student-led protests.

Earlier this week, Greta arrived in New York at the end of a sailboat trip across the Atlantic from Europe to support a growing climate strike movement in America and to continue speaking out in advance of a United Nations Climate Summit in September.

Some worry about the effects of all this attention on Greta, who has suffered from depression and autism. I don’t. Her mind is strong, and so are her heart and her voice. “I think in many ways we autistic are the normal ones and the rest of the people are pretty strange, especially when it comes to the sustainability crisis,” she said. We should listen to Greta. We must.

Greta’s quest brings to mind the students at Marjory Stoneman Douglas High School in Parkland, Florida. Last year, a shooter killed 17 there, most of them teenagers. In the aftermath, surviving students found their voices and are speaking truth to power, unafraid to approach the movers and shakers and demand action to stop the gun violence. They’re still at it.

Last week, their organization called March for Our Lives unveiled their “Peace Plan for a Safer America,” a comprehensive program they argue would cut in half the number of deaths by gun violence in 10 years. “Policymakers have failed, so survivors are stepping up,” March for Our Lives co-founder David Hogg wrote, “We’re not just fighting against the status quo, we’re fighting for real change, for justice, for peace.”

Fighting for justice and peace, for real change.

These mature young adults are fighting for more than that. They are fighting for their lives and their future  — the messy world we are leaving them. The Gretas and Davids of today can see their future lives more clearly than we older folks can. They are worried, and they are speaking out. But are we listening?

We must.