The overwhelmingly dominant human contribution to climate change appears to be the human impact on the global carbon dioxide concentration. For 400,000 years before industrialization, the global average concentration never exceeded 300 ppm. Since industrialization, it has risen from 285 parts http://pmkpmk.comeze.com per million (ppm) CO2 to approximately 380 ppm, with a steep climb in the past few decades. Climate scientists predict that our present rate of growth in carbon emissions will result in a global average of 700 ppm CO2. Most climate scientists agree that we should stabilize the concentration between 450 and 550 ppm by the year 2100 in order to limit global average temperature to a 2 degrees Celsius increase above current climate.