We are now at AR5 with zero warming since AR4. The last IPCC report which actually experienced any warming was SAR in 1995. In fact, the vast majority of the IPCC’s history has seen zero warming, and prior to that the warming was primarily due to rebound from Mt. Pinatubo cooling.
This complete lack of warming through most of the IPCC’s history has led them to 95% certainty that humans are heating the world out of control.
That level of certainty “has increased with every report,” notes Dr. Hayhoe, an expert reviewer for the IPCC. “Because we have more data, we have more science, we have more observations.”