The organization 350.org is promoting Saturday, October 24th, as an International Day of Climate Action. According to their website, http://www.350.org, they are "calling on people around the world to organize an action on October 24 incorporating the number 350 at an iconic place in their community, and then upload a photo of their event to 350.org website."
350.org is an international campaign dedicated to building a movement to unite the world around solutions to the climate crisis—the solutions that science and justice demand. Their mission is to inspire the world to rise to the challenge of the climate crisis—to create a new sense of urgency and of possibility for our planet.
Their focus is on the number 350—as in parts per million, the level scientists have identified as the safe upper limit for CO2 in our atmosphere. But 350 is more than a number—it's a symbol of where we need to head as a planet.
Policy Innovations, a publication of the Carnegie Council, has an online article about the International Day of Climate Action you might be interested in reading.