October 24, 2009 is the International Day of Climate Action, and author Bill McKibben’s advocacy movement known as 350.org has been getting a lot of attention. 350.org is coordinating a widespread day of environmental action with one goal: solutions to the climate crisis.

Why 350? McKibben argues that it is the safe upper limit in atmospheric carbon dioxide, measured in parts per million. In order to avoid an environmental catastrophe, it’s the number targeted by this movement. In this week’s Yale Environment 360, economist Frank Ackerman argues that what is good for the Earth is good for the wallet. Of course, it is an alarming idea that this is the “safe” level of carbon dioxide in the atmosphere as we are at 390 already – and rising.

Though 350.org’s wide umbrella includes some efforts that are problematic, the message is a powerful one: the time for solutions is now. The medium of that message, hundreds of thousands of people at 4,000 events in 170 countries, is even more striking.

To locate an event in your local community, use the map below:

To hop on this trajectory of a reduction in global carbon dioxide levels, learn the 5 things that New Englanders must do in 5 years, and 5 things that you can do in 5 minutes.