Young people afraid for their futures protested around the globe Friday to implore leaders to tackle climate change, turning out by the hundreds of thousands to insist that the warming world can't wait any longer.

Marches, rallies and demonstrations were held from Canberra to Kabul and Cape Town to New York. More than 100,000 turned out in Berlin.

Many of the demonstrators were students who skipped school to take part in the second "Global Climate Strike," following a similar event in March that drew large crowds.

In Washington, several thousand young people marched to the Capitol building carrying signs reading "There is no Planet B" and "This can't wait until I finish high school."

"Basically our earth is dying and if we don't do something about it, we die," said A.J. Conermann, a 15-year old sophomore. "I want to grow up. I want to have a future."

The protests were partly inspired by the activism of Swedish teenager Greta Thunberg, who has staged weekly demonstrations under the heading "Fridays for Future" over the past year, calling on world leaders to step up their efforts against climate change.

"It's such a victory," Thunberg said in an interview Friday with The Associated Press in New York. "I would never have predicted or believed that this was going to happen, and so fast — and only in 15 months."

Thunberg spoke at a rally later Friday and was expected to participate in a U.N. Youth Climate Summit on Saturday and speak at the U.N. Climate Action Summit with global leaders on Monday.

"They have this opportunity to do something, and they should take that," she said. "And otherwise, they should feel ashamed."

In New York, where public schools excused students with parental permission, tens of thousands of mostly young people marched through lower Manhattan, briefly shutting down some streets.

"Sorry I can't clean my room, I'm busy saving the world," one protester's sign declared.

Thousands of young people in Boston rallied at City Hall Plaza to demand "bold climate action" at the local, state and federal levels. The student crowds were bolstered by supporters coming from earlier rallies on the Harvard and MIT campuses and outside the Cambridge offices of Google, Microsoft and Amazon. Former Environmental Protection Agency head Gina McCarthy was among the keynote speakers at the Massachusetts event, NBC Boston reported.

Students across the Bay Area walked out and protested, both on and off campuses, to bring attention to the challenges the planet faces and to call on lawmakers to take action.

"[Climate change is] going to have a serious impact on the earth, and we're going to have to live on the earth in the future," Vigha Yarlagadda, a student at Dougherty Valley High School in San Ramon, said. "It's going to impact us more than it will the older generations."

In South Florida teen activists rallied at Miami Beach city hall shouting "Miami is under attack!" to underline concerns over sea levels rising in their coastal community.

In Chicago, students walked out as well and marched to Federal Plaza for a rally featuring performances and speeches, organizers said.

Hundreds of young demonstrators marched through downtown Mexico City, chanting "political change, not climate change!" — an apparent reference to President Andrés Manuel Lopez Obrador's push to increase production and processing of fossil fuels. High school student Maria Martinez carried a sign reading: "You'll die of old age; I'll die of climate change."

In Brazil, about 80 young people gathered outside the Rio de Janeiro state legislature, some carrying signs saying "SOS Amazonia" and "Save our future."

One protester held up a sign that said "Rio 2050" and showed the city's landmarks underwater, with the iconic Christ the Redeemer statue's head poking out.

Brazil found itself at the center of the global conversation about climate change in recent months when an increase in fires in its Amazon region caused an international outcry.

The protesters on Friday said far-right President Jair Bolsonaro's administration was doing too little.

Julia de Oliveira is a 16-year-old high school student. She said: "Having this discourse of being climate change deniers will produce no result. We need this government to open its eyes."

School teacher Yuri Diniz Leite says Brazil must recognize the privilege of having so much of the Amazon in its territory.

Friday's demonstrations started in Australia, where organizers estimated 300,000 protesters marched in 110 towns and cities, including Sydney and the national capital, Canberra. Demonstrators called for their country, the world's largest exporter of coal and liquid natural gas, to take more drastic action to reduce greenhouse gas emissions.

"Even though we ourselves aren't sick, the planet which we live on is, and we are protesting and fighting for it," said Siobhan Sutton, a 15-year-old student at Perth Modern School.

Hundreds of rallies took place across Europe, including in the Czech Republic, Germany, Britain and Poland, which is still widely coal-reliant and where many middle schools gave students the day off to enable them to participate in the rallies in Warsaw and other cities.

In Berlin, police said more than 100,000 people gathered in front of the capital's landmark Brandenburg Gate, not far from Chancellor Angela Merkel's, office where the Cabinet thrashed out the final details of a 54 billion euro ($60 billion) plan to curb Germany's greenhouse gas emissions.

Thousands of schoolchildren and their adult supporters demonstrated in London outside the British Parliament, some holding home-made placards with slogans including "Don't be a fossil fool" and "Make our planet Greta again," in a reference Thunberg.

The British government said it endorsed the protesters' message but didn't condone skipping school — a stance that didn't sit well with some of the young protesters.

"If politicians were taking the appropriate action we need and had been taking this action a long time ago when it was recognized the world was changing in a negative way, then I would not have to be skipping school," said Jessica Ahmed, a 16-year-old London student.

In Helsinki, the Finnish capital, a man dressed as Santa Claus stood outside parliament holding a sign: "My house is on fire, my reindeer can't swim."

Smaller protests took place in Asia, including in Japan, South Korea, the Philippines, Hong Kong and India.

"We need to reclaim our constitutional right to clean air and water," said Aman Sharma, a 16-year-old protester in India's capital of New Delhi.

In Tokyo, hundreds of students and environmental activists marched through the business and shopping district of Shibuya, chanting "Climate Justice!" while holding hand-painted placards with messages such as "Go Green" and "Save the Earth."

Smaller rallies were held in more than a dozen other cities around Japan, including Kyoto, the nation's ancient capital that hosted the 1997 climate conference.

And in the Afghan capital, Kabul, an armored personnel carrier was deployed to protect about 100 young people as they marched, led by a group of several young women carrying a banner emblazoned with "Fridays for Future."

Fardeen Barakzai, one of the organizers and head of the local climate activist group, Oxygen, said Afghan youths "know the problem of climate change. We know war can kill a group of people. ... The problem in Afghanistan is our leaders are fighting for power, but the real power is in nature."

In Africa, rallies were held in Johannesburg and the South African capital, Pretoria, as well as Kenya's capital, Nairobi, where some young protesters wore hats and outfits made from plastic bottles to emphasize the dangers of plastic waste, a major threat to cities and oceans.

Climate change "is worse than homework," one sign proclaimed.

Experts say Africa is the most vulnerable continent to climate change and the least equipped to deal with it. Governments have pleaded for more support from the international community.

The world has warmed about 1 degree Celsius (1.8 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.

Nations around the world agreed at a 2015 summit in Paris to hold warming to less than 2 degrees Celsius (3.6 Fahrenheit) more than pre-industrial-era levels by the end of this century.

However, 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 referred to 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.

The U.N. summit is aimed at eliciting concrete proposals from various countries to make progress toward the Paris goal.

Thunberg is expected to participate in a U.N. Youth Climate Summit on Saturday and speak at the U.N. Climate Action Summit with global leaders on Monday.

"They have this opportunity to do something, and they should take that," she said in the interview. "And otherwise, they should feel ashamed."