This image consists of two line graphs, one showing the concentration of carbon dioxide gas, and the other the temperature changes from the present. Both graphs have identical horizontal axes representing the years before the present, ranging from 400 000 years before the present to 0 (which represents the year 1950). The vertical axis for the carbon dioxide concentration graph represents carbon dioxide concentrations measured in parts per million by volume, with values ranging from 160 to 300. The temperature change graph has its vertical axis representing annual temperature change from the present in degrees Celsius, with values ranging from minus 10 to plus 4. The general trend shows that when carbon dioxide concentrations peak there is a corresponding increase in temperature, and when they drop the temperature drops as well. Although temperature changes follow the same general trend there appears to be far more variability in the temperature changes.