If I'm reading the graphs correctly the atmospheric CO2 was approximately at the same level we are today.
Not my area of expertise so interested to see other's takes on this.
Carbon Dioxide Levels Lower Than Thought During Super Greenhouse Period [2].
Do high levels of CO2 in the past contradict the warming effect of CO2 [3]? There are also other drivers for climate besides CO2.
Life on earth have enjoyed unparallelled stability for past 10K years [4], so have no historical frame of reference for what happens if temperature breaks free from this zone.
Extinction events on earth for past 300 million years are associated with CO2 concentrations above 900 ppm [5], page 8.
[1] https://gml.noaa.gov/ccgg/trends/gl_gr.html
[2] https://www.dartmouth.edu/press-releases/carbon-dioxide-leve...
[3] https://skepticalscience.com/co2-higher-in-past-intermediate...
[4] https://earth.org/data_visualization/a-brief-history-of-co2/
[5] http://burro.case.edu/Academics/USNA229/impactfromthedeep.pd...
Where this gets complicated is wether earth is due another ice age or not as well.
The sun gets hotter over the course of millions of years as it is inching closer to death. However we are talking about millions of years, not the last 200 years. CO2 levels on earth fall and we end up maintaining roughly the same temperatures. If we reach record CO2 levels we are also going hit record temperatures. When I was still in high school I got fooled by so many articles talking about how we are in or entering a solar minimum and how it is about to get colder. What a joke. If the heating effect of human activity is enough to outdo a solar minimum we know it's human made.