A wave of climate change protests swept the globe Friday, including in Atlanta. Hundreds of thousands of young people looked to send a message to leaders headed for a U.N. summit: The warming world can’t wait for action.

In Atlanta, a few hundred people gathered on the steps of the state Capitol.

People carried signs, participated in chants and listened to speakers. The crowd ranged from kids with their parents to high school and college students — some of whom said this was their first time participating in a rally like this.

“Coming this morning from working on an assignment, hitting the books. And coming here, it’s sort of like the real word version of what the books are teaching us. So it’s really nice to see,” said Margaret Williford, 23, masters of public policy student at Georgia State.

“And seeing all the kids here, like even younger than me, I almost started crying at one point seeing all these little kids with these signs in both a good way and a bad way because it’s hopeful and it’s heartbreaking that we’ve reached this stage where these children now have to leave school and come out and fight so that they can have an Earth to live on,” Williford said.

The “Global Climate Strike” events ranged from a gathering of about two dozen activists in Seoul using LED flashlights to send Morse code messages calling for action to rescue the earth to Australia demonstrations that organizers estimated were the country’s largest protests since the Iraq War began in 2003.

Madison Hunter brought her 5-year-old son, London, to the protest in Atlanta.

“Children definitely are our future, so it’s really important that he understands that we all need to take care of this planet the best that we can,” Hunter said.

In New York, where public schools excused students with parental permission, tens of thousands of mostly young people rallied and marched through lower Manhattan.

“Sorry I can’t clean my room, I’m busy saving the world,” one sign declared.

The world has warmed about 1.8 degrees Fahrenheit since before the Industrial Revolution, and scientists have attributed more than 90 percent of the increase to emissions of heat-trapping gases from fuel-burning and other human activity.

Scientists have warned that global warming will subject Earth to rising seas and more heat waves, droughts, powerful storms, flooding and other problems, and that some have already started manifesting themselves.

Climate change has made record-breaking heat temperature records twice as likely as record-setting cold temperatures over the past two decades in the contiguous U.S., according to National Oceanic and Atmospheric Administration data.

Nations around the world agreed at a 2015 summit in Paris to hold warming to less than 3.6 degrees Fahrenheit more than pre-industrial-era levels by the end of this century.

But U.S. President Donald Trump subsequently announced that he was withdrawing the U.S. from the agreement, which he said benefited other nations at the expense of American businesses and taxpayers.

Trump called global warming as a “hoax” before becoming president. He has since said he’s “not denying climate change” but is not convinced it’s manmade or permanent.