Mann’s Hockey Stick shows that temperatures have risen about half a degree over the last 1000 years. Let’s assume for the sake of argument that he is correct.
Ice core data shows that temperatures regularly vary by about 12C, and that current CO2 levels are unprecedented for hundreds of thousands of years.
Given the massive growth of CO2, one might expect to see a huge increase in temperatures. The graph below overlays Mann’s hockey stick on the Vostok ice core data.
The hockey stick (inside the red circle on the right side) is essentially invisible, because it is completely within the noise of natural variability. Michael Mann has shown us that CO2 sensitivity is extremely low.
But it is worse than it seems. At Vostok, temperatures have actually declined, while CO2 has risen 40%. Under Hansen’s forecasts, Vostok should have risen 3-5C by now.
So there you have it. Hansen, Mann and Rahmstorf have definitively debunked themselves.
arctic ice data co2 and warming