Carbon: Breaking a 800,000 Year Cycle...

"There is a remarkable record of CO2 concentrations preserved in tiny bubbles in Antarctic ice cores going back 800,000 years. These measurements are less accurate than modern Keeling-style instrumental readings, but they are plenty accurate enough to see the big picture clearly. All throughout the past 800,000 years, which encompasses several ice ages and interglacial warming periods, CO2 levels fluctuated in a relatively narrow band between about 180 ppm (during the colder ice ages) to 280 ppm (during the warmer interglacial periods). For about the last 10,000 years we have been living in a warm interglacial period, with CO2 concentrations at about 280 ppm. Then, beginning with the industrial revolution about 1750, CO2 concentrations gradually moved up to Keeling's accurately measured 1958 level of 315 ppm. Since then, as we have seen, CO2 concentrations have grown rapidly to the current 2013 level of 400 ppm.

So, the current CO2 concentration of 400 ppm is some 40 percent higher than anything that has been attained in the last 800,000 years. The glacial-interglacial cycles began some two and a half million years ago. Scientists estimate that a CO2 concentration of 400 ppm has not been attained for at least 3 million years. This rapid a change in CO2 concentrations has probably not occurred for tens of millions of years...." cont at link:

http://www.pbs.org/newshour/businessdesk/2013/05/the-odds-of-disaster-an-econom-1.html