Two Accidental Experiments

a, Annual mean daily emissions in the period 1970–2019 (black line), updated from the Global Carbon Project1,3 (Methods), with uncertainty of ±5%. The red line shows the daily emissions up to end of April 2020 estimated here. b, Daily CO2 emissions in 2020. Diagram copied from Le Quéré et al (2020).

The present Covid-19 lockdown provides an ideal opportunity to test one of the fundamental assumptions of the anthropogenic climate change theory by observing its effects on atmospheric CO2 concentration. It is an accidental experiment. If accepted theory of the global carbon cycle is correct, the change in human-caused CO2 emissions shown in the diagram above should be observable in the month by month rate of change of CO2 concentration in the atmosphere.

It is not observable!

a. Monthly rate of change of CO2 concentration at Cape Grim, Tasmania. b. Monthly rate of change of CO2 concentration at Mauna Loa, Hawaii. In both cases seasonal effects have been removed. Heavy black lines show the 13 month running means and the dotted lines show the 2σ confidence limits. c. Sea surface temperature in the Eastern Equatorial Pacific (“Nino 3”). The two peaks occurred during the 1998 and 2016 El Nino’s (vertical dashed lines).

Graphs a and b above show no significant variation in monthly differences for the first 5 months of 2020.  The negative value in a is the difference between December 2019 and January 2020, i.e. before the lockdown.



Le Quéré, C., Jackson, R.B., Jones, M.W. et al. Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement. Nat. Clim. Chang. (2020).