People worldwide poured into the streets Friday for a youth-led climate strike that aimed to pressure global governments to step up their efforts to tackle the planetary emergency at a key United Nations summit scheduled to start Monday.

"Striking is not a choice we relish; we do it because we see no other options."

—Youth leaders

"Striking is not a choice we relish; we do it because we see no other options," youth climate leaders Greta Thunberg of Sweden, Luisa Neubauer of Germany, and Angela Valenzuela of Chile wrote Friday in an op-ed for Project Syndicate.

"We have watched a string of United Nations climate conferences unfold," they added. "Countless negotiations have produced much-hyped but ultimately empty commitments from the world's governments—the same governments that allow fossil fuel companies to drill for ever-more oil and gas, and burn away our futures for their profit."

Youth strikers have no plans to slow down. World leaders everywhere, take note: "Our message is simple: the eyes of all future generations are upon you. Act accordingly." https://t.co/MY40YJgxFC #climatestrike — 350 dot org (@350) November 29, 2019

Thunberg, whose solitary protests outside the Swedish Parliament last year led to the global Fridays for Future movement, is currently sailing from the United States to Europe for the U.N. Climate Change Conference, or COP 25. The summit, which runs through Dec. 13, was moved from Santiago, Chile to Madrid, Spain in late October.

Reuters reported Friday that "Thunberg had been due to join a student strike in Lisbon, but her environmentally friendly voyage across the Atlantic from New York by yacht was hit by high winds, delaying her by a few days."

However, the 16-year-old Swede's absence did not deter locals from striking. Marianna Louca, 14, told Reuters that "we wish she'd been here, but the movement has to carry on without her. We've got to send our message and pressure politicians ahead of the climate summit."

Finally got to march with #ExtinctionRebellion in my hometown which, like many, is highly endangered by the #ClimateEmergency! What do we want? #ClimateJustice. When do we want it? #now. #FridaysForFuture #Lisbon pic.twitter.com/5uTIxdOSNV — Telma Laurentino (@TelmaLaurentino) November 29, 2019

According to Fridays for Future's map that tracked the latest round of demonstrations, more than 2,000 strike events were planned around the world Friday.

Today youth strikers around the world are mobilising again in a Global #ClimateStrike. It's not too late to find a strike near you at https://t.co/Oo0tsyEgTM If you're looking for resources this climate strike, you can also head to https://t.co/MTIAHxZ9sN pic.twitter.com/Obi5L2O76j — 350 dot org (@350) November 29, 2019

The protests kicked off in Australia—parts of which faced "catastrophic" bushfires in recent weeks that provoked intense demands from the public and progressive politicians that the country's Liberal-led coalition government ramp up its response to the climate crisis.

Ahead of a demonstration at the Liberal Party's Sydney headquarters Friday, Shiann Broderick, a teenager from Nymboida whose family home was destroyed in the fires, sent a message to Australian Prime Minister Scott Morrison: "Your thoughts and prayers are not enough."

"People are hurting," Broderick said in a statement. "Communities like ours are being devastated. Summer hasn't even begun."

Fridays for Future protesters demonstrated outside an incineration plant in New Delhi, India, toting signs that read "Stop the monster incinerator" and "Don't burn garbage wet or dry. Don't make landfills in the sky."

Protesters from various cities and countries across the globe carried signs that featured calls for swift climate action, some written in English. In Hong Kong, activists' signs read, "Stop denying the planet in dying" and "The seas are rising, and so are we." In Thailand, signs declared that "Climate change is class war" and "It's our future."

In Manila, Philippines, climate strikers gathered at Plaza Miranda and "Statue of the Sentinel of Freedom," a monument to Lapu-Lapu, a former ruler of the island Mactan.

Covering the strike events in Germany, The Associated Press reported:

In Berlin, about two dozen environmental activists jumped into the chilly waters of the Spree river in front of parliament to protest a government-backed package of measures they say won't be enough to reduce the country's greenhouse gas emissions. The package was blocked Friday by Germany's upper house, which represents the country's 16 states. Later, tens of thousands of students rallied in front of the Brandenburg Gate. "The generations before us messed it up," said 17-year-old Robin Ebelt. "And we're the ones that will feel the consequences. I would like to spend another 60 years on this planet, grow old, and have grandchildren."

Advocates of ambitious climate policies filled streets in major European capitals, from Berlin to Rome to Vienna.

The demonstrations fell on Black Friday—a global shopping event that comes the day after the U.S. holiday Thanksgiving. Some participants in Friday's climate demonstrations highlighted how consumerism negatively impacts the environment.

"We need to stop telling ourselves that, 'it's Christmas, I need to go shopping,'" said Théophile Pouillot-Chévara, a 17-year-old climate activist in Paris, where some protesters blocked stores and faced off with shoppers. Critics of consumerism also raised alarm about Black Friday in Brighton, England.

Around the United Kingdom, demonstrators drew attention to the country's upcoming election and urged voters to support candidates backing bold climate policies.

"We are striking today all across the world because we need radical climate action now," tweeted Youth Strike 4 Climate, a Fridays for Future campaign run by the U.K. Student Climate Network. "In the U.K. we're striking to make sure this is the #ClimateElection. The media must do better at covering this issue, and the electorate must #VoteClimate on December 12th."

Protests were planned in more than 80 locations across the United States Friday, according to a statement from the Youth Climate Strike Coalition. Earlier this year, the coalition released its primary policy demands: a Green New Deal, respect of Indigenous land and sovereignty, environmental justice, protection and restoration of biodiversity, and implementation of sustainable agriculture.

"We are striking because our leaders haven't been listening to us," said Maya Arengo of Fridays For Future USA, one of the coalition's member groups. "They think our voices are ones they can ignore and not take seriously. They don't understand that we, the youth, are terrified for our futures and we won't stop fighting until our futures are secure."

Climate activists are planning another strike for next Friday. The events around COP 25 follow a pair of massive strikes in September—which coincided with a U.N. summit in New York City and drew millions of participants around the world—as well as major youth-led strikes in May and March.