July 2017: 407.07 ppm
For updates, click here. This is simple. As CO2 rises, the heat-trapping blanket over Earth thickens, and traps more heat. I don't think humans have a collective "death wish," so nonviolent political action is needed. 350.org, as the name says, wants this number at 350 ppm, or lower. 350.org is sponsoring a September 8, 2018, global RISE FOR CLIMATE. What have I done? Everything here, and more.
August 20, 2018, Update from Dahr Jamail: "I’ve spoken to prestigious scientists both on and off the record who believe that sooner rather than later, global population will be reduced to around 1 billion humans." (at truthout.org)