It's getting warmer ...

Suggestive, but not indicative. If there's any location in America susceptible to the urban heat island effect, it's Sky Harbor Airport (and the Phoenix metropolitan area in general, for that matter).

Yes, the heat island effect is certainly in play here. I don't think there can be any doubt about it. But I suspect that there's something else going on as well.

Not only the urban heat island, but the fact that the figures will be fudged, and upwards.

http://www.ncdc.noaa.gov/img/climate/research/ushcn/ts.ushcn_anom25_dif…

This is a NASA offshoot.

They have been happily creating man made GW, by adjusting figures up.

This is on top of the UHI.

Nick

Yes, of course anthropogenic global warming is fabricated. How stupid of me not to know that. *slaps head*

I have no doubt that AGW is playing a role in this; my comment just meant to point out that the effect of AGW on the Sky Harbor data is hard to pull out.

Arguing with people like Nick is a waste of time. They already know what the "answer" is, and do the equivalent of sticking their fingers in their ears and going "la-la-la I can't hear you" when you point out that their "facts" are wrong.

The procedure that is used to adjust the U.S. Historical Climatology Network (USHCN) data Nick cited without explanation is described here.

The adjustment that makes the biggest difference and produces the upward trend is the adjustment for time of observation bias:

Next, the temperature data are adjusted for the time-of-observation bias (Karl, et al. 1986) which occurs when observing times are changed from midnight to some time earlier in the day. The TOB is the first of several adjustments. The ending time of the 24 hour climatological day varies from station to station and/or over a period of years at a given station. The TOB introduces a non climatic bias into the monthly means. The TOB software is an empirical model used to estimate the time of observation biases associated with different observation schedules and the routine computes the TOB with respect to daily readings taken at midnight. Details on the procedure are given in, "A Model to Estimate the Time of Observation Bias Associated with Monthly Mean Maximum, Minimum, and Mean Temperatures." by Karl, Williams, et al.1986, Journal of Climate and Applied Meteorology 15: 145-160.

The station history adjustment program (accounting for such things as weather station location moves) also accounts for some of that change, as does the adjustment for the replacement of liquid-in-glass thermometers with Maximum-Minimum Temperature System (MMTS) sensors.