"A nearby station, 25km away, Clinton, IL, is also in the GISS database and shows less of a trend during the same period"

How not to measure temperature, part 63 « Watts Up With That?

The Stevenson Screen housing the thermometer is about 5 feet away from each tank, while the concrete building in the background is some 50 feet away. You’d think that they could have placed the station a little further away. Again, as we’ve seen time and time again, the placement is not often about the best location, it is about convenience for the observer.

The GISS graph of temperature over the station history shows a fairly strong warming trend from about 1980 to the present. The question is, how much of that is from increased throughput of the sewage treatment plant responding to population growth, and how much of it is climate change?