Human deforestation and burning of fossil fuel has raised atmospheric CO2 to over 380 ppm in the last century, well above pre-industrialized levels, and "off the scale" of this graph top.
The mean global temperature in the carboniferous period, with CO2 concentrations over double of present day was an astounding, just wait for it... 14C, which is the incredible, * unbelievable* 0C above the mean present day global temperature.
As CO2 levels spiked in the carboniferous period, it is marked by the drop of sea levels by 120m to the present day level, and as the CO2 level subsided, the sea levels rose 80m.
Sorry, but "off the scale" only counts when you actively pick and choose what scale you want to use, which in terms of geological temperature, CO2 and O2 concentrations quite literally means disregarding millions of years of geological time.
As other people have said, life on earth will go on in one form or another. But "off the scale" is a necessary term in this context to drive home the incredible turmoil and human suffering that will result as we are forced to adjust the local pressures of water shortages, mass human migration, and agricultural failures that will be caused by this...
Also, when discussing matters scientific, please cite your scientific sources --- otherwise the discussion is of little value. Like so:
http://www.nature.com/nature/journal/v449/n7159/abs/nature06...