For a long time scale, a rapid warming is associated with a rapid increase in greenhouse gases. This causes ocean acidification. Ocean acidification leaves a clear record in the paleontological record. The last one which was comparable to what we're doing through now was https://www.britannica.com/science/Paleocene-Eocene-Thermal-... about 55 million years ago. And current projections for the speed and severity of acidification are worse. Which indicates that the warming that we are going through is also faster than that experienced at any point in the last 55 million years.