@dbattistella @ed_hawkins Why was it getting colder before the Industrial Revolution despite constant CO₂ levels? In part due to decreasing sunlight from orbital changes (the Milankovitch cycles). This is indicated by the orange curve in the attached chart. In blue is the CO₂ levels measured by trapped air in the Antarctic, and the temperature is in red, from three separate sources depending on time period. #ClimateChange #Paleoclimate #MilankovitchCycles