Adapted from the weekly newsletter GreenBuzz, published Mondays.

Last week was a dreadful one for humanity. There’s no nice way to put it. There was a hate-filled mass shooting in New Zealand (and the resulting social media blowback), malfunctioning airplanes, more Brexit madness, a college admissions scandal, a political stalemate in Venezuela, saber-rattling in North Korea and way too much dysfunction in Washington, D.C.

Okay, so maybe all that passes for "normal" these days. Dreadful nonetheless.

Even on the environmental front, the world’s nations came together to make their first global commitment to cut the growing use of single-use plastics — but the United States blocked efforts for bold action. Sigh.

There was one bright light — more than a million of them, actually — that deserves further illumination: On Friday, school kids in more than 120 countries skipped classes to protest grownups’ inaction on climate change. More than 1.4 million youth by some accounts, in more than 300 cities from India to Indiana, took to the streets with a message in more than 40 languages: Take action now or risk their future, and ours.

It was a harsh rebuke of my generation, and probably yours, too.

The climate strike was a harsh rebuke of my generation, and probably yours, too.

The one-day climate strike was inspired by Greta Thunberg, the 16-year-old Swedish wunderkind who has become the global face of youth concerns about the climate crisis. Thunberg, you may recall, made a splash in December, when she excoriated negotiators at COP24 in Katowice, Poland, then again in January, when she similarly censured the global elite at the World Economic Forum conference in Davos, Switzerland.

Since, then, Thunberg has become the de facto climate spokesperson for the Gen-Z crowd. The rest of us owe her a debt of gratitude.

Youth often have led major social and political shifts, especially when their elders were unable or unwilling to get the job done. I have a little personal experience here: The first Earth Day and many of the Vietnam-era anti-war marches took place during my high school years, and my peers and I were on the streets, marching, yelling, carrying signs and pleading to our elected representatives. (In truth, my activism began years earlier, at age 8, when I appeared on local TV news in support of nuclear disarmament.)

And while my idealism has been tempered by pragmatism (and, on my worst days, cynicism), those early experiences shaped my belief that mass movements can, over time, engender mass change.

More recently, we’ve seen other youth movements around the world that have helped draw attention to critical issues, even if they didn’t necessarily tip the balance: on gun safety, immigration reform, Tiananmen Square, Arab Spring, Standing Rock.

And now, climate.

Ultimately, last week's marchers’ status as media darlings will fade away as we turn our attention to so many other pressing issues and distractions. But that doesn’t mean the activists will vanish. The persistence of youth — like the drip, drip, drip of water on a rock — has been shown over history to wear down even the toughest barriers, not the least of which can be the intransigence, negligence or timidity of their elders. Leaders such as Thunberg inevitably inspire others, such as this remarkable young author. Suddenly, a woke teen has sparked a revolution, or at least shamed grown-ups to act.

Over the coming months, youth climate strikes are set to continue, with organizers already planning the next ones. In September, for example, world leaders will gather in New York to adopt concrete plans to dramatically reduce their nations’ greenhouse gas emissions. Young demonstrators will likely will be out in full force, making their case on a global stage before the world’s most powerful leaders.

And it’s not just about climate. Increasingly, this generation understands that climate change is connected to a range of other environmental, social and economic issues, including growing income inequality, choking pollution in cities around the world and the weakening of democratic institutions. Lest there be any question, all are inextricably linked, and these young activists are coming to understand that.

We haven’t heard the last from Ms. Thunberg and her peers. Last week, she was nominated for a Nobel Peace Prize. Regardless whether she wins, it’s likely she’ll continue to be an impassioned (and media-savvy) voice for those most affected by the climate crisis: the generation that will live to see its most severe impacts, but with the least power to do something about them. And the movement she catalyzed will, no doubt, be an enduring touchpoint in a growing global wave of climate activism.

At least, that’s my hope. Given the headlines these days, we need all the optimism we can get.