350 means safety from the climate crisis. To preserve our planet, scientists tell us we must reduce the amount of CO2 in the atmosphere from its current level of 392 parts per million ("ppm")to below 350 ppm. But 350 is more than a number—it's a symbol of where we need to head as a planet. At 350.org, we're building a global grassroots movement to solve the climate crisis and push for policies that will put the world on track to get to 350 ppm. Join In by Signing Up >> Read more about the science behind 350.