State of Our Climate
​Atmospheric CO2 Concentration
NOAA 10 Mar 2016 'Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years. It’s explosive compared to natural processes'. Today’s human-made CO2 increase is 200 times faster, a dramatic rate compared to natural processes, Pieter Tans, leader of NOAA’s Global Greenhouse Gas Reference Network
Preindustrial 
​concentration (WMO)
CO2 278 ppm ​
At over 400 ppm atmospheric CO2 is the highest in 15-20 million years
2009 A. Tripati Coupling of CO2 ...  of the Last 20 Million Years 
​2013 Yi Ge Zhang A 40-million-year history of atmospheric CO2
CO2 unprecedented rate of increase  (WMO 2017)
1 June 2020 Atmospheric CO2 highest in 23 million years 
Why are CO2 emissions highly cumulative
​ in the atmosphere?​
VIDEO Scripps animation record of atmospheric CO2,
​800,000 year ago to 2019

NOAA ESRL
​Greenhouse gas concentrations
November 2021
​417 ppm mean.