Even worse, the ice core record has been well known for at least 2/3 of my 70 year lifetime. Likewise has the co2 concentration from ice cores been known for the last several decades. The truth of all of this is just too inconvenient for the hucksters.
CO2 proxies showed that CO2 levels were lower than pre-industrial levels when liquid water was present.
The conclusion? The climate is obviously far more sensitive to CO2 than we thought. LOL