This statement has been proven time and time again, once you get rid of all the cherry picked, scaremongering BS.
Broadly speaking, and we can address the specific changes due to man’s net release of CO2 into the atmosphere a bit later, the following true:
When CO2 levels were steady, global average temperatures rose.
.(But at the same rate they were rising between 1975 – 1996.)
When CO2 levels were steady, temperatures were steady.
When CO2 levels were steady, temperatures fell.
.(Again, at the same rate that they fell between 1945 and 1975.)
When CO2 levels rose, temperatures fell.
When CO2 levels rose, temperatures were steady.
When CO2 levels rose, temperatures rose at the same rate that they rose when CO2 levels were steady.