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PPM means "parts per million."  It's the unit scientists use to measure the concentration of carbon dioxide in the atmosphere.

Bill McKibbon and others at have given "ppm" another meaning.  PPM stands for, they say, the "people powered movement" that is working to build an economy that is prosperous and low-carbon. 

Whether you care deeply about climate science or preserving a fluourishing earth—or both—consider adding a PPM CO2 widget to your own site or blog.  Once there, the numbers update automatically each month.  And you will help keep the latest CO2 readings out in front and top of mind.