(September 20, 2014) — Celebrities, activists and political leaders are expected to join more than 100,000 people in New York City on Sunday for what organizers say will be the largest climate-change march in history.

The “People’s Climate March” has been endorsed by more than 1,400 organizations, including environment, faith and justice groups, as well as labor unions. Students have also mobilized marchers at more than 300 college campuses for the event, which calls on world leaders to do more to confront the threat of climate change and comes ahead of a United Nations climate summit.

“People from all walks of life, all over the world care deeply about climate change and are extremely worried and scared and so this march is showing the huge variety of people and the huge variety of reasons that people are invested in this issue,” march organizer Rachel Schragis told Al Jazeera.

Hollywood actor Leonardo DiCaprio, former US Vice President Al Gore, U.N. Secretary General Ban Ki-moon and New York Mayor Bill de Blasio are expected to participate in Sunday’s march — which will wind its way through Midtown Manhattan on a two-mile route starting at 11:30 a.m.

After a moment of silence at 1 p.m., participants will be encouraged to use instruments, alarms and whistles to make as much noise as possible, helped by marching bands and the tolling of church bells.

Around the world, more than 2,700 climate events in 158 countries are planned to coincide with the New York march, including rallies in New Delhi, Jakarta, London, Melbourne and Rio de Janeiro.

Recapturing Lost Momentum
Sunday’s march will come ahead of a meeting of over 120 world leaders at the U.N. next week, who will convene for a one-day climate summit on Tuesday. The hope is to recapture the momentum lost after the disappointing 2009 climate summit in Copenhagen. However, few decisions are expected beyond galvanizing political will for a new global climate treaty.

Still, Ban and other U.N. officials hope the summit will energize negotiations on reaching a deal on cutting greenhouse gas emissions and set the stage for a crucial conference in Paris in December 2015 aimed at finalizing an agreement.

“We are breaking ground here on many different levels,” Executive Secretary of the U.N. Framework Convention on Climate Change (UNFCCC) Christiana Figueres told reporters. “First, we’re going to see unprecedented public mobilization for climate action.”

President Barack Obama will attend the summit and is expected to highlight strides the US has made on climate change, senior administration officials said Thursday.

The US heads into the summit in the strongest position it has been in years. It has cut emissions by 10 percent from 2005 to 2012, more than any other country. Officials say about half of that reduction is due to the economic recession, but it puts the US well on its way toward meeting its goal to cut emissions by 17 percent by 2020 from 2005 levels.

Political ‘lip service’
But whatever emerges from the one-day summit Tuesday is unlikely to bring the world closer to a goal set back in 2009: Preventing Earth’s temperature from rising 2 degrees Fahrenheit from where it is now.

Rather than firm commitments from closed-door negotiations, the summit is expected to jumpstart a series of much-publicized initiatives and partnerships. The heads of state for both India and China, two of the world’s largest carbon polluters, are not expected to attend the summit, further dimming hopes of meaningful action.

There have also been concerns about funding for poorer countries on the frontlines of the fight against climate change and their ability to move away from fossil fuels and protect their citizens. While richer countries made a commitment in 2009 to raise $100 billion by 2020 for less-affluent countries, so far only Germany has made a significant pledge to the fund, the Guardian reported.

In the weeks leading up to the summit, the World Meteorological Organization said that concentrations of carbon dioxide, the chief greenhouse gas, increased more in 2012 and 2013 than in any year since 1984. The months of May, June and August were the warmest of any on record in the United States. A study issued earlier this year said the West Antarctic ice sheet was starting to collapse and was unstoppable.

“We hear these warnings from scientists. They’re becoming increasingly panicked and our politicians sort of pay lip service to how concerned they are about climate change on the one hand. But on the other hand, it’s basically ‘drill baby drill,'” activist Naomi Klein told Al Jazeera “They’re opening up all kinds of new frontiers for fracking, for tar sands, for coal and so people in the streets are going to be expressing their sense of urgency.”

Al Jazeera and wire services. Kristen Saloomey contributed to this report from New York.