[cogitator]

The results of this study suggest that very small towns, with populations measured in mere hundreds of inhabitants, likely have urban heat islands that are on the order of the entire amount of global warming that is believed to have occurred since the end of the Little Ice Age. With such small aggregations of people having such a dramatic impact on air temperature, it is ludicrous to believe that on top of the natural warming experienced by the earth in recovering from the Little Ice Age we can confidently discern an even more subtle increase in background temperature caused by concomitant increases in greenhouse gas concentrations. Changes in population, which have generally been positive nearly everywhere in the world over this period, could easily explain whatever tiny bit of warming is left after the natural component of warming (which must be substantial, relatively speaking) is subtracted from the total amount of warming recorded by the totality of earth's thermometers over the past century or so.

I've got a bit of time (not much) so I'm going to try and reply to some points in the posts that have piled up.

With respect to the above, this issue of "urban heat island" effects can be argued incessantly and to no resolution. For every paper that shows an urban heat island effect, I can likely find one that doesn't.

Science relies on independent corroboration. What is required is an independent data set, collected and analyzed differently, that provides a similar output. There is such a data set available.

Borehole temperature profiles. These temperature profiles, which are available from every continent except Antarctica, and which are generally rural (it's rare to go drilling in the middle of a city, or even a small town), show the same amount of warming in the past 150 years as the surface temperature record.

When you assess that data set, also figure in that some of the more mainstream skeptics (such as Patrick Michaels, Richard Lindzen, Sallie Baliunas) also agree that the warming in the past century was about 0.6 C/1 F. Michaels in particular accepts it and only expects about 1.5 C maximum warming in the next 50 years (I think ancient_geezer notes this).

So I think it's pointless to argue about how much warming has occurred in the past century. It's much more fruitful to try to determine what has caused it (recovery from Little Ice Age, solar variability, greenhouse gases, land-use changes, etc.) and then to try to assess the likely contribution of each of these factors in the next century. Some of them are out of our control, like solar variability. Some of them are in our control, like greenhouse gases. So those things that we are capable of controlling, we should attempt to do a good job of assessing how much they are really contributing. As I've noted numerous times, James Hansen of GISS has written that the contribution from CO2 can likely be best controlled by market forces and new technology in the next 50 years, so it makes more sense to concentrate on black soot aerosols, methane, and CFCs.

OK, onto the next post.

[Number_Cruncher]

Science relies on independent corroboration. What is required is an independent data set, collected and analyzed differently, that provides a similar output. There is such a data set available.

The borehole temperatures are calibrated against the surface records that are probably contaminated with urban heat islands, so it is not an independent data set as cogitator falsely claims. There is an independent data set, namely pressure transducers on balloons that can measure the temperature in the surface layer from 1000 to 850 mb. Pielke showed that there was very little warming in this layer and thus strongly indicates the surface network measurements are flawed.

Link here for a review.