What this graph proves is that even IF mankind is influencing the temperature, it is insignificant compared to the natural forces that are apparent when you look back 400,000 years. But the temperature change over the last 150 years could mostly be due to coming out of the Little Ice Age that lasted from 1200 to 1850. Mankind’s effect is likely a small part of this recent warming and an artifact of Urban Heat Island (UHI) effect.