Thats why there is error margins you fucking idiot. Do even saw the graphs? Its shown there. Ofc they are not 100% certain of the temperature back then but they have records of it and they uncertainty margins.
Also you have no fucking clue about basic physics and chemistry about CO2 and you dont understand that now the rate of CO2 ppm is way faster causing ecosystems to unbalance. Kys pls. Thx