As you probably know, the world's most prominent measuring station for atmospheric carbon dioxide concentration recorded on Thursday, May 9th, a daily average value over 400 parts per million. Daily atmospheric measurements of carbon dioxide began first in Hawaii in 1958 and registered 315 ppm then.
See also: http://keelingcurve.ucsd.edu/.
The news that the world crossed the 400 ppm marker triggered a rush of good reporting about awful facts. Papers around the world noted that the last time earth's atmosphere had 400 ppm was about 4 million years ago, well before the evolution of humans, and when tropical forests covered parts of what is now Canada.
The scientific record is robust and tells us all that atmospheric concentrations of carbon dioxide fell to about 180 ppm at the time of the last ice age and remained between 180 ppm and 280 ppm for 800,000 years, until the advent of the industrial revolution.
And since humans have been burning large amounts of fossil fuels--coal, oil, and gas--with the industrialization of earth, the atmospheric concentrations of carbon dioxide have been increasing at the fastest rate most likely in the history of the earth. And the rate of increase continues to escalate.
That brings us to the very worst climate science fact of the last week full of them. The annual rate of carbon dioxide increase has jumped from 0.7 ppm to 2.1 ppm. We are adding more carbon still faster.
Indeed, the increase in just 2012 was a truly terrible 2.6 ppm, according to NOAA data. At that rate of increase, atmospheric carbon concentration will reach 450 ppm in just 19 years. And so, most of those under 50 years old will live on a planet fundamentally transformed, as our climate speeds toward disaster.