In AR4 chapter 3, there is a two-page section (p 252-253) titled

Frequently Asked Question 3.1
How are Temperatures on Earth Changing? 

These FAQ sections from AR4 WG1 are also available as a separate file. 

The second sentence of FAQ 3.1 says:

"For the global average, warming in the last century has occurred in two phases, from the 1910s to the 1940s (0.35°C), and more strongly from the 1970s to the present (0.55°C)."

On the following page is the figure we have discussed before:

Looking at this figure, is the warming from the 1910s to the 1940s 0.35°C?  No!  Looking at the smoothed blue line, the temperature rise over this period is about 0.5°C. Not for the first time, the IPCC's own data shows that their claim is false.  

Furthermore, it is clear from this diagram that the rate of temperature rise during the period 1910-1940 is about the same as the rate of temperature rise from 1970-2000, so the "more strongly" statement by the IPCC is incorrect.

It is apparent that the IPCC is attempting to downplay the warming in the first half of the 20th century, and exaggerate the warming in the second half.  This is in order to support the IPCC  hypothesis that the warming is due to carbon dioxide, which increased significantly only in the late 20th century. The fact that the warming phases in the first and second halves of the century are very similar shows that this IPCC hypothesis is false. 

Remarkably, the authors of this section managed to write another false statement in the very next sentence: "An increasing rate of warming has taken place over the last 25 years". In fact, we have seen that the rate of warming has slowed in recent years, and over the last ten years there has been no warming at all.