350.org

An international campaign with the mission to raise awareness and fuel solutions to the climate crisis.  The number 350 represents the amount of carbon dioxide in the atmosphere (in parts per million) that scientists have calculated to be the maximum amount that Earth can sustain.  It is hypothesized that CO2 concentrations beyond 350ppm will accelerate the affects of global warming.  350.org organizes worldwide events to demonstrate the wide spread concerns regarding climate change issues, with the intent to motivate political leaders to  commit to reducing carbon by 80% by 2050.

It should be noted that the atmosphere contained approximately 275ppm for all of human history until 200 years ago when it began to rise with the onset of the industrial revolution.   Additionally, statistics show that we are currently at 390ppm.  , It appears that sometime between 1985 and 1990, the atmospheric concentrations of CO2 reached 350ppm.