Let’s get together — yeah, yeah, yeah.

This isn’t quite as obvious as it sounds. Different groups have sprung up at different times to fill different niches. You wouldn’t look out at a marsh and say, “It would be much nicer if there were just one kind of frog to keep track of.” Diversity has some very real purposes.

But there are moments when unity is essential — and this is one of them. We’re up against the most sustained assault on the environment ever: In the last few weeks, our oldest environmental groups have had to play nonstop defense just to keep Congress from gutting the Clean Air Act. A president elected on the promise of transformational energy change has reverted to opening vast tracts of Wyoming to new coal mining. A Tea Party House has actually voted to deny the science of global warming.

Behind all this is a very unified fossil-fuel industry. Working through the Koch brothers, the U.S. Chamber of Commerce, and a couple of other fronts, they’re busy buying votes and supplying disinformation. And they’re winning.

To fight back effectively, we need a much louder voice. That’s why this week we’re joining together two of the big mass movements around climate change: 1Sky and 350.org. 1Sky has been coordinating efforts on the ground across the United States; 350.org has been at work in 188 countries around the world. We’ll now all operate under the 350 banner, in an effort to put forward a unified message on every front.

That message starts with simple science: Our foremost researchers, like NASA scientist James Hansen, have shown that 350 parts per million CO2 is the most we can safely have in the atmosphere, a level we’ve already exceeded. No matter how the House votes, physics and chemistry still call the tune.

But the message goes beyond science to politics. We have learned over time that you can’t win simply by explaining the crisis to political leaders; they may intellectually understand that they’re facing the end of the world, but what they really fear is the end of their political careers. We need to build a movement that can reward and punish politicians. Since we’ll never have the money to match the fossil-fuel front groups, we’re going to need a different currency: bodies, creativity, passion.

It is possible to rally passion. Both 1Sky and 350.org have demonstrated the ability to find and energize a new generation of environmental supporters, one that crosses all demographic and linguistic boundaries. Together, as the new 350.org, we’ll be speaking with one voice. Shouting, actually — trying to drown out the talk from dirty energy and dirty money.