Global temperatures and atmospheric CO2 concentrations have been much higher in the deep past.
However the ice cores show that today's atmospheric CO2 methane is far higher than any time in the past 800,0000 years. The rate of global warming today is unprecedented .
Atmospheric CO2 (423.9 ppm April 2024) is 50% higher than preindustrial 278 ppm)
It maximum over the past 800,000 years is 300 ppm
Atmospheric methane (1928 ppb) is 166% or over two and a half times higher that its pre-industrial level (722 ppb).
Furthermore the rate of increase in atmospheric CO2 is unprecedented (IPCC and WMO).
Unprecedented
Multiple lines of evidence show that the rate at which CO2 has increased in the atmosphere during 1900–2019 is at least 10 times faster than at any other time during the last 800,000 years (high confidence), and 4–5 times faster than during the last 56 million years. I
PCC AR6 WG1