Thousands of climate advocates descended on London Friday for the first day of “The Big One,” a multi-day mass mobilization aimed at pressuring the United Kingdom’s government to stop approving new fossil fuel projects and accelerate the transition to renewable energy as key environmental indicators signal time is running short.

The mass demonstrations, set to run through Monday, were organized by a broad alliance of climate, labor, peace, and social justice organizations including Extinction Rebellion, Greenpeace, PCS Union, NHS Workers Say No, Mothers Rise Up, Global Justice Now, and dozens of other groups with the recognition that “we need to come together to win.”

“We believe that we will win as a movement,” Mel Evans of Greenpeace U.K. said Friday. “The more people that come, the louder our message will be.”

Organizers anticipate that the protests will grow in size on Saturday—which marks Earth Day—and throughout the weekend, with 100,000 people expected to attend demonstrations outside Parliament and dozens of other planned events that, at their core, will deliver the same message: End the era of fossil fuels or face climate catastrophe.

“The desire to make this broad doesn’t mean we’re any less radical in our demands,” said Nick Dearden, the director of Global Justice Now. “We need to fundamentally transform the way our economy works, nationally and globally, and we’re in no doubt about the scale of the challenge in front of us to achieve that.”

The start of “The Big One” coincided with the Friday release of the World Meteorological Organization’s State of the Global Climatereport, which showed that “concentrations of the three main greenhouse gases—carbon dioxide, methane, and nitrous oxide—reached record highs in 2021.”

The United Nations agency noted that “real-time data from specific locations show that levels of the three greenhouse gases continued to increase in 2022” as rich nations—including the U.K. and the United States—continued burning fossil fuels and approving new oil and gas projects despite increasingly dire warnings from the scientific community.

“Today’s report confirms what we already knew: that fossil-fueled climate devastation reached a fever pitch in 2022,” said Lisa Göldner of Greenpeace’s Fossil Free Revolution campaign. “And it’s showing no sign of letting up in 2023, with a deadly heatwave hitting Asia this month and ice sheets melting faster than ever. But it’s business as usual for the fossil fuel industry, whose calling card seems to be greenwashing their public image while continuing to commit devastating climate crimes.”

“The solution is staring us in the face: the fossil fuel industry must die—not people,” Göldner added. “As long as the mighty power of the fossil fuel industry remains unbroken, the climate crisis will continue to escalate. Global governments have to step up; we want all new fossil infrastructure projects stopped this year, global emissions halved by 2030, and ultimately fossil fuels phased out for good. It’s a total no-brainer.”

#UniteToSurvive thousands of rebels outside the Home Office calling on the government to take real action to address the #ClimateEmergency pic.twitter.com/L5exadxSuV

— Extinction Rebellion UK 🌍 (@XRebellionUK) April 21, 2023

#UniteToSurvive thousands of rebels outside the Home Office calling on the government to take real action to address the #ClimateEmergency pic.twitter.com/L5exadxSuV

— Extinction Rebellion UK 🌍 (@XRebellionUK) April 21, 2023

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