geological evidence stretching back tens of thousands of years, obtained by drilling into the Vostok ice core in Antarctica, is now available. And that temperature record makes alarmingly clear how extraordinary would be a 6° increase in global temperature by 2100.
This is a classic from the year 2000. The ice core data (turquoise line) shows recent temperatures cooling. They threw in a fake hockey stick in red at top of the graph without explanation, and used the same color for CO2 in the bottom graph. The graph is designed to confuse the reader into believing the opposite of what it shows.
The large increase in ice core CO2, corresponds with a decline in ice core temperatures.