More than a decade after 350.org was founded, one of the most common questions we still get is “what does that name mean”? Well, it’s less complicated than you’d think. 

350.org stands for 350 ppm of CO2 in the atmosphere, what’s considered the safe amount to avoid the worst impacts of the climate crisis. The concept of ppm may be unfamiliar to non-scientists, but it’s an easy one: Imagine a huge ball pit, like those some little kids like to play in. Now imagine you fill it up with one million blue balls. And now replace 350 blue balls with 350 red balls. You still have one million balls, but 350 are now red. Right? Well, that means that the ball pit has 350 ppm (parts per million) red balls. If instead of balls you talk about molecules, and instead of a ball pit you talk about the atmosphere, then you’re talking about us.

We need our atmosphere to contain less than 350 ppm of CO2, but it currently contains around 420 (you can learn more about science here and check the daily CO2 levels here). Our fight is to keep fossil fuels in the ground in order to return as fast as possible to that safe level.

So our name, 350.org, is a compass to bring us back to safety and an homage to the science that guides us. But it is much more than a number. It’s also a reminder of where our home is, and who’s with us in this journey. 350.org and our movement is diverse, widespread, made of people just like you and me – and we invited some of them to share what the name “350” means to them: