This Saturday, 24 October, people in 181 countries celebrated the international day of climate action with more than 5,200 actions, in what was the largest day of environmental action ever organized. From the Himalayas to the Great Barrier Reef, from schoolchildren to politicians, participants rang bells, planted trees, scuba dived, climbed mountains, crossed bridges, and danced in the streets, all in the name of combating climate change, demanding a fair and ambitious climate change deal at the climate negotiations in Copenhagen this December.
The efforts were reported in newspapers around the world, and captured in photos and videos which can now be seen on the web page of 350.org, the non-profit organization that led the day of action.
Actions ranged from the directly environmental to the artistic, from the religious to the revelrous – as people planted trees artists created 3 minute 50 second sound art, believers gathered on cathedral steps to have their climate pledges blessed and even club-goers found a way to show their support as they “danced to save the world.” A choreographed flash mob stopped traffic in Hong Kong, 20,000 students rallied in Addis Ababa, participants in Sydney spelled out the number 350 in umbrellas on the steps of the opera house, and deep sea divers in the Maldives brought the number underwater.
“Together, we’ve shown the world that a global climate movement is possible and set a bold new agenda for the upcoming United Nations climate meetings in Copenhagen this December,” stated Bill McKibben, environmental activist and founder of 350.org.
“The 350 target is the new bottom line for climate action and world leaders must now meet that target.”
Until approximately 200 years ago, CO2 levels were at approximately 275 ppm, but since the industrial revolution carbon dioxide levels have been rising. Levels are currently at 390ppm, and concentrations are rising by about 2ppm per year.
350ppm is an ambitious target. The Intergovernmental Panel on Climate Change(IPCC) in their 2007 fourth assessment report identified 450ppm as the ceiling for carbon dioxide levels in order to keep global warming in check.
Science and Civil Society
350ppm wasn’t a number being discussed widely in the climate change debate until the winter of 2008, when the NASA scientist James Hansen published the results of a study concluding that if there were more than 350 parts per million of CO2 in the atmosphere, we couldn’t have a planet "similar to the one on which civilization developed and to which life on earth is adapted." 
Research such as Hansen’s has encouraged activists and organizations such as 350.org that have been working to bring more ambitious targets into the public debate as part of a worldwide civil society movement working for a fair and binding deal in Copenhagen and beyond.
This summer, the UN climate scientist Rajendra Pachauri, chairman of the IPCC lent clout to the 350 target when he stated in an interview that: "as chairman of the Intergovernmental Panel on Climate Change, I cannot take a position because we do not make recommendations But as a human being I am fully supportive of that goal. What is happening, and what is likely to happen, convinces me that the world must be really ambitious and very determined at moving toward a 350 target."
Another day of action, The Global Time to Sign, is being planned for December 12, 2009, halfway through the Copenhagen climate talks. You can read more about it or see how to participate here.
Here are a few of the thousands of images from this year’s actions around the world:
You can see more than 15,000 photos from the day of action here.
This article is available in Spanish.