NEW YORK — It's hard to make a really big protest march about just one thing. Back in the days of giant rallies against the Iraq war, all sorts of groups wanted in on the action. There were communists. Anarchists. Protesters mad about the Florida recount. Katrina justice groups. Civil rights organizations. And more. The crazy quilt of aggrieved demonstrators made it hard to keep the focus on protesting the war.

A similar dilemma faced organizers of the giant People's Climate March, which clogged a big part of Manhattan on Sunday afternoon. At times it seemed as if the whole Lefty world, pushing every Lefty cause, had showed up to march down 6th Avenue. Who was that guy with the "FREE LEONARD PELTIER NOW!" sign? Okay, that was just one person. But what about the people waving the "INDIGENOUS RIGHTS PROTECT US ALL" banners? The "Resistencia Indigena"? What about all the unions — Teamsters, UAW, SEIU, Amalgamated Transit Union, and more? What about the VOCAL-New York marchers, who say their mission is to "build power among low-income people affected by HIV/AIDS, the drug war and mass incarceration"? What about the Jews for Racial and Economic Justice? And the "TAKE BACK THE CITY — HOMES FOR ALL" people? What about the Fresh Direct protesters, angry at the company that wants to build a facility on a Native American burial ground in the Bronx? What about the "WE ARE ALL MIGRANTS" people? And the ones who seemed to step out of a time warp to chant "the people, united, will never be defeated"? And of course, what about all those jugglers and guys banging drums?

The genius of the People's Climate March, at least as far as its organizers and participants were concerned, is that the concept of climate is broad and flexible enough to cover everything. It's about saving the Earth, and all of its inhabitants. (Well, maybe not for the woman shouting and waving a sign saying "ONE CHILD PER FAMILY," who apparently wants to save the Earth by depopulating it.) When People's Climate is the banner, any sort of Lefty cause can be subsumed underneath it. Thus the "DECOLONIZATION COOLS THE PLANET" people, and the "CLIMATE CHANGE IS A HEALTH CARE CRISIS" people, and the "VEGANISM SAVES THE PLANET" guy all march together.

Just as the world's indigenous people are threatened by climate change, so are vegans, and those affected by HIV/AIDS and mass incarceration, and SEIU shop stewards, and more. The People's Climate March was kind of a reverse "Seinfeld" — it was a protest about everything.

Of course, there was plenty of demonstrating focused on specific environmental issues, like fracking. But out of the entire cacophonous mess, a big theme emerged at the march, and it was the idea of "climate justice." In its simplest form, that means it is time for those who concerned about global warming to start kicking ass.

One of the most arresting images at the march came not from any of the big groups, but from a single protester wearing the Guy Fawkes mask popularized in the movie "V for Vendetta," a mask which later became a favorite of the Occupy Wall Street movement. The man held aloft a handmade sign that said simply: "ANGRY PACIFIST." Nearby, and throughout the crowd, were lots of people waving professionally-printed signs that said "TAX WALL STREET —END CLIMATE CHANGE." And throughout, there was chanting: "What do we want?" "Climate justice." "When do we want it?" "Now!" (A particularly enthusiastic group was serenading former Vice President Al Gore and New York Mayor Bill de Blasio as they walked the route.) The effect was to bring the spirit of the Occupy movement to the global warming issue. And the message was: We've had it. It's time to make those one percenters, and giant corporations, and frackers, and, of course, the Koch brothers pay for their environmental crimes.

"Climate justice" is a hugely popular concept on the Left. As one group, the Climate Justice Alliance, describes it, climate justice activists seek to "forge a scalable, and socio-economically just transition away from unsustainable energy towards local living economies to address the root causes of climate change." And more:

We are rooted in Indigenous, African American, Latino, Asian Pacific Islander, and working-class white communities throughout the U.S. We are applying the power of deep grassroots organizing to win local, regional, statewide, and national shifts. These communities comprise more than 100 million people, often living near toxic, climate polluting energy infrastructure or other facilities. As racially oppressed and/or economically marginalized groups, these communities have suffered disproportionately from the impacts of pollution and the ecological crisis, and share deep histories of struggle in every arena, including organizing, mass direct action, electoral work, cultural revival, and policy advocacy.

The answer for most of these inequities, as climate justice activists see it, is a massive transfer of wealth, both within the United States and from the U.S. and other developed countries to poorer nations around the world.

Among the many groups listed as People's Climate March sponsors, a total of 47 have the word "justice" in their titles. There is Interfaith Youth for Climate Justice. The Alliance for Global Justice. Earthjustice. Barnard-Columbia Divest for Climate Justice. Congregations for Peace and Justice. Arise for Social Justice. Mount Holyoke Climate Justice Coalition. Interreligious Eco-Justice Network. NYC Environmental Justice Alliance. And many more.

Put it all together — all the justice demanders, the tax Wall Streeters, and the spirit of Occupy symbolized by the angry pacifist — and the People's Climate March was one long, loud, loosely organized demand that vast sums of money be taken from the wealthy and given to the clients of the coalitions and alliances and networks and task forces that make up today's environmental justice movement. They've had enough of debating climate models. They want to start taking — now.