How do we know climate change is linked to CO2 in the atmosphere?
Over the last 650,000 years the natural range for CO2 concentrations in the atmosphere has been between 180 to 300 parts per million (ppm). This data has been found through ice core surveys, where air trapped as the ice froze hundreds of thousands of years ago, has been carefully analysed. The graph below shows the results of the ice core measurements along side temperature up until the year 1950. The graph shows that the amount of CO2 in the atmosphere up until 1950 had never exceeded 300ppm.
