On this sweltering day, it feels fitting to give a heads-up about 350.org, an awesome grassroots organization that’s addressing the climate crisis—global warming, climate choas, and its many manifestations. What’s with the number 350? It’s the level of carbon dioxide (in parts per million) that is safe and sustainable for human life on our dear little planet. We’re currently at 387.81 (not good, not good at all)—but we can work toward lowering it. To that end, 350.org is organizing an awareness and action event, the International Day of Climate Action, when people and communities around the world will come together to urge citizens and leaders everywhere to step up their work on this important issue.

In the words of author and environmental activist Bill McKibben, who heads up 350.org, “People everywhere are figuring out that 350 is the most important number on earth, that October 24 is going to be the most widespread day of climate action ever, and that six weeks before the big UN talks in Copenhagen we’ll stand together to change the debate on climate change.”

Learn more, find an event, or create your own!