In 2003, a paper was published in Nature:
E Kalnay and M Cai (2003) Impact of urbanization and land-use change on climate, Nature 423, 528−531.
This paper made the point that changes in land use, such as urbanization and the development of agriculture, could have had a significant influence on the climate.
This paper was criticised by two comments ("Brief Communications") in Nature, the following year:
K E Trenberth (2004) Nature 427, 213
R S Vose et al (2004) Nature 427, 213-214
As is generally the case, the journal allowed Kalnay and Cai to reply to this criticism on the next page:
M Cai and E Kalnay (2004) Nature 427, 214.
Now IPCC AR4 discussed this issue in chapter 3, page 244:
"Comparing surface temperature estimates from the NRA with raw station time series, Kalnay and Cai (2003) concluded that more than half of the observed decrease in DTR in the eastern USA since 1950 was due to changes in land use, including urbanisation. This conclusion was based on the fact that the reanalysis did not explicitly include these factors, which would affect the observations. However, the reanalysis also did not explicitly include many other natural and anthropogenic effects, such as increasing greenhouse gases and observed changes in clouds or soil moisture (Trenberth, 2004). Vose et al. (2004) showed that the adjusted station data for the region (for homogeneity issues, see Appendix 3.B.2) do not support Kalnay and Cai’s conclusions."
So the IPCC mentions the original paper and the two criticising papers, creating the impression that Kalnay and Cai were incorrect. But the IPCC does not refer to Cai and Kalnay's response to the criticism, where they point out that Trenberth's comment is based on a "common misunderstanding". Nor does the IPCC refer to a later (2006) paper by Kalnai et al that found significant influence of land surface effects on temperature trends in the US.
This unfair imbalance and bias in reporting the literature is particularly bad because the lead author of IPCC chapter 3 is none other than Kevin Trenberth, the author of the first comment. Trenberth appears to be abusing his position as lead author by citing his own work but not the response to it.
See also this post by Roger Pielke.