The Cambrian period had 7000ppm of CO2 in the atmosphere.

That was a time of the perpetual fire.

Even though the solar luminosity at the time was 4% weaker than today, the earth was much hotter due to the free amounts of carbon dioxide.

Slowly chemical weathering and living organisms bound the carbon in the atmosphere so, at the time of the Carboniferous period, it had reached 180ppm.

The earth was much cooler. A wonderful time with 34% oxygen in the air.

Then after this period, flood basalt eruptions, such as the Siberian traps and the Deccan traps released vast amounts of CO2, and this caused the earth to heat up again.

That was an inferno. 90% of all life died.

This followed by slow weathering out of CO2 and subsequent cooling.

When the CO2 levels are in low and balance the earth temperature change due to the Milankovitch cycles. During such period the climate always changes.

We even had ice ages during this period.

Now there is no flood basalt eruption at all. This time it is we humans who released the CO2 in the atmosphere. It took us one hundred years.

Earth will be warm. It will be hot.

(Source: youtu.be slash r7aZ6vqCk2E)