[elvisabel78]

Your words here approximate the truth more than those from your earlier post, because you now focus on local urban areas, and not on global land-based temperature records represented in the graphs that we've seen, and that originated this discussion. You first stated:

The land-based temperature records are an artifact caused by urban heat islands.

But the IPCC found that this urbanization heat has had a minimal effect in these records:

Extensive tests have shown that the urban heat island effects are no more than about 0.05°C up to 1990 in the global temperature records used in this chapter to depict climate change. Thus we have assumed an uncertainty of zero in global land-surface air temperature in 1900 due to urbanisation, linearly increasing to 0.06°C (two standard deviations 0.12°C) in 2000. link

[elvisabel78]

And it has also been found that:

• "Contrary to generally accepted wisdom, no statistically significant impact of urbanization could be found in annual temperatures." link

• The trends in urban stations for 1951 to 1989 (0.10°C/decade) are not greatly more than those for all land stations (0.09°C/decade).

• Simlarly the rural trend is 0.70°C/century from 1880 to 1998, which is actually larger than the full station trend (0.65°C/century) link

[aruanan]

Thus we have assumed an uncertainty of zero in global land-surface air temperature in 1900 due to urbanisation, linearly increasing to 0.06°C (two standard deviations 0.12°C) in 2000.

Yes, but global land-surface temperatures are extremely spotty outside the developed world. It's in the developed world where there are the most extensive and long-running records that are plagued by the effect of urban heat islands. Besides, the IPCC (especially the political arm of the IPCC) has already demonstrated that it's not an objective, neutral participant in all this.