The claim that our planet has been in a period of rising carbon dioxide (CO2) levels, especially after 1940, is true.
The claim that rising CO2 in the air causes runaway global warming is false.
CO2 levels have been higher than today during most of Earth's history.
There is no evidence our planet has ever had runaway warming from CO2 levels up to ten times higher than today.
There is strong evidence CO2 is a minor variable for climate change.
That would be the best explanation of why we have had three different CO2 - average temperature relationships, while CO2 levels rose every year for the 75 years after 1940:
(1) Cooling from 1940 to 1975
(NOT WARMING),
(2) Flat trend between 1975 and the 1993 low
(NOT WARMING),
(3) Warming from the 1993 low, to the 2003 high
(WARMING), and
(4) Flat trend from the 2003 high to 2015
(NOT WARMING).