I wonder how they chose a time period both for the initial display and for the total. What's special about last 800k years? Full context: https://u4d2z7k9.rock

I wonder how they chose a time period both for the initial display and for the total. What's special about last 800k years? Full context: https://u4d2z7k9.rocketcdn.me/wp-content/uploads/2020/08/Co2-levels-historic.jpg https://u4d2z7k9.rocketcdn.me/wp-content/uploads/2020/08/Co2... from https://earth.org/data_visualization/a-brief-history-of-co2/ https://earth.org/data_visualization/a-brief-history-of-co2/