"Concentrations of (CO2) extracted from s drilled in Greenland and Antarctica have typically ranged from near 190 parts per million by volume (ppmv) during the ice ages to near 280 ppmv during the warmer "interglacial" periods like the present one that began around 10,000 years ago. Concentrations did not rise much above 280 ppmv until the Industrial Revolution. By 1958... they had reached 315 ppmv, and they are currently ~370 ppmv and rising at a rate of 1.5 ppmv per year... Human activities are responsible for the increase. The primary source, fossil fuel burning, has released roughly twice as much... as... required... for the observed increase. Tropical deforestation also has contributed to carbon dioxide releases during the past few decades. The excess... has been taken up by the oceans and land ."