Well, that didn't take long.
Four days ago (May 9) the Mauna Loa Observatory recorded CO2 measurements topping 400ppm (parts per million) for the first time since measurements began in 1958, and likely for the first time since man has existed. In '58 the CO2 levels were just over 300ppm, and rising at about 0.7ppm/year. Today the levels are shooting up at over 2ppm/year.
Climate scientists warned for a long time that we needed to try to keep the levels from going beyond the 350ppm mark but of course were ignored and, worse, treated to scorn and "skepticism" from those representing either corporate/political interests (read Naomi Oreskes book, Merchants of Doubt) or ideological absurdities from clueless people like James Inhofe, who asserts that climate change is not possible because, “God’s still up there.”