Hundreds of thousands of demonstrators turned out in a series of worldwide events Sunday to demand action to combat climate change. The largest rally was held in New York City, where organizers estimate up to 300,000 people took part. Smaller demonstrations took place in scores of cities around the globe, including marches in London, Rio de Janeiro, Berlin and Melbourne.

The goal of the demonstration in New York, dubbed the “People’s Climate March,” was to pressure world leaders to take steps to address climate change. “People around the world are tired of waiting for our politicians to act. From the islands of the Pacific to the streets of New York City, we’re demanding action, not words,” said Payal Parekh, Global Campaigns Director for 350.org, one of the main sponsors of the event.

The march was held in advance of a special United Nations climate summit, which commences on Tuesday. The summit is not a negotiating session, but rather is limited to what UN Secretary General Ban Ki-moon described as an “opportunity for leaders to champion an ambitious vision, anchored in action that will enable a meaningful global agreement in 2015.”

Neither Tuesday’s summit nor the upcoming conference in 2015 is expected to yield anything meaningful to reverse the growth of greenhouse gas emissions or to adapt to a changing climate. President Obama has already ruled out a legally binding treaty, instead opting to pursue a series of toothless political commitments from individual countries.

Members and supporters of the Socialist Equality Party distributed thousands of copies of a statement, “Climate change and the capitalist system,” published on the World Socialist Web Site. The statement explained that the only way to conduct a serious fight against global warming and other environmental disasters is through a political struggle against capitalism and the nation-state system, on the basis of an international socialist program.

The inability of the existing political and economic system to protect humanity from the climate crisis motivated the large attendance at Sunday’s march. Protesters came from throughout the United States, with hundreds of buses carrying contingents from all 50 states. Among them were large numbers of college students.

Demonstrators carried signs warning of the urgency of the environmental crisis, documenting the impacts already felt in communities across the world, and demanding the replacement of fossil fuels with renewable energy sources.

Yet organizers saw to it that the demonstration would offer no serious challenge to their allies in the political establishment. The core sponsors of the march included Democratic Party adjuncts in environmental organizations, trade unions and liberal advocacy groups, including the Sierra Club, 1199 SEIU, and MoveOn.org spinoff Avaaz. Over 1,500 organizations eventually endorsed the rally.

Following Occupy Wall Street’s “participatory model,” which suppresses issues of program and leadership and thus blocks any opposition to the capitalist program of the Democratic Party, its corporate backers and the trade unions, the organizers made no explicit demands other than attempting to attract the largest numbers possible. They welcomed corporate sponsors with open arms.

There were no speeches at Sunday’s event, which thus had more the character of a parade than a political demonstration. Participants were encouraged to use noisemakers to “sound the smoke alarm for a planet on fire.” The march concluded with a “block party” on an isolated stretch on the far West Side of Manhattan, far away from the UN headquarters where President Obama and other world leaders will make speeches Tuesday and adopt a posture of concern over global warming.

Lending the event in New York even more of an official character, Ban Ki-moon and scores of other political dignitaries took their places in the crowd. New York City Mayor Bill de Blasio participated, tweeting, “Proud to walk in #PeoplesClimate March on Sunday. It’s everyone’s responsibility to leave a livable planet for the next generation.”

One third of the New York City Council joined the mayor at the event. Former Vice President Al Gore and Senator Bernie Sanders of Vermont also took part. The aim of these politicians, together with the event organizers, was to use the demonstration to promote illusions in the Democratic Party and mobilize support ahead of midterm elections in November.