but, Hansen famous, The Earth system is already showing signs of performing, Even in the instances of "Slow feedback" such as ice sheet changes.The human caused release of increased carbon dioxide into the atmosphere also presents climate scientists with something they've never seen in the 65 million year record of carbon dioxide levels a drastic rate of increase rendering it difficult to predict how rapidly Earth will respond. In periods when carbon dioxide has grown due to natural causes, the interest rate of increase averaged about.0001 parts per million per year quite simply, One hundred parts per million every million several