We already know the science on climate change. Now we need to act.

Gov. Bobby Jindal spoke for politicians everywhere last week when the Louisiana Republican, asked about climate change, said “Absolutely, let’s listen to scientists … But let’s not do so in a way that hurts our economy.”

In other words, Jindal is happy to change if it doesn’t require, you know, changing. That’s basically what every political leader in the world has said in recent years, right up to President Barack Obama. It’s why the Copenhagen climate conference in 2009 was such a fiasco, and why the United Nations climate summit in New York next week is unlikely to get much done.

It’s why the largest climate demonstration in history is coming to New York this weekend—hundreds of thousands in the streets to demand that, for once, our leaders deal with reality.

We don’t want to hurt the economy—in fact, we’d like to save it before it sinks in the rising oceans, withers in the growing deserts, and melts in the rising mercury. The world’s economists said on Monday that we could get off fossil fuel over the next few decades at no net cost. But we can’t do it if our leaders won’t pay attention.

Or rather, we can’t do it if they keep paying attention to the campaign cash that comes from the fossil fuel industry. The Koch brothers are some of the richest people on earth, thanks to money that comes from oil and gas extraction, and they’re also two of the biggest political players ever, effectively owning the GOP. Chevron, which gave the single biggest corporate campaign donation in history before the last election, has now given up on greenwashing altogether, selling off their tiny renewable division earlier this month. Forget solutions — the oil industry just does problems.

And so we take to the streets. If the scientists are ever going to get heard above the rustle of cash, they need some amplifiers. That’s all of us. We’ll be out in the streets in the largest political demonstration the United States has seen in years, and the largest climate change rally in world history.

We know the science—that part is easy. There’s already way too much carbon in the atmosphere, about 400 parts per million. That’s 50 parts per million more than what scientists say is safe, and it’s why California is burning up right now. There’s too much carbon underground for us to ever burn safely: The scientists have made it clear we need to leave 80% of the gas, oil, and coal we know about underground, where it can do no harm. That’s why we’re fighting the Keystone pipeline; that’s why it was so sickening last week to see the Obama administration open up vast new tracts of federal land in Colorado for coal mining.

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Unlike politicians, we’re grown-ups. We can take the actual news scientists give us, and we can act on it. In Germany, as a front page story in The New York Times made clear this week, the world’s most prosperous economy now runs largely on renewable energy. Not because Germany has a lot of sun—but because it has a lot of political will.

Happily, political will is an inexhaustible resource. If you’re in New York on Sunday, in fact, you’ll see it happening — a couple hundred thousand people changing the political zeitgeist. Making the world a more dangerous place for the Jindals, and a slightly safer one for the rest of us.