Old Rocks
Diamond Member
But we didn't exist as a species for virtually all of that time. As a species with have only existed within the present cycles of glacial and inter-glacial periods. You made a reference to the Milankovitch Cycles, and I showed you where we should be in the present cycle. We are far warmer than we should be, and the cause of that is the injection of GHG's into the atmosphere by the burning of fossil fuels.Your graph is only looking at tiny space of time in earth's 4 billion year existence, and temperatures from the past are only calculated guesses.
A short history of measuring temperature
For temperature since about 1850, scientists can refer to the "instrumental record." This is a world wide record based on standardized thermometer readings from thousands of meteorological stations around the world.A short history of measuring temperature
mathbench.umd.edu