Using the line for the Annual mean, calculate the average annual rate of increase between 1960 and 1980, and between 1990 and 2010. Show your working and dont forget to give UNITS for numerical values. Annual rate of increase = (final value initial value) / (number of years) Has the rate of increase become higher or lower? If carbon dioxide continues to increase at the same rate, what level will it reach by 2020? Do you think it will increase at the same rate, or will the rate of increase grow? Why? The graph below shows the monthly and annual means of the volume of carbon dioxide (CO2) measured in the atmosphere at Mauna Loa..