In a resent post I showed how BEST "global" surface temperature data made a very good reconstruction of "Global" Sea Surface Temperatures by using a modern satellite era baseline and scaling BEST Tave to the HadSSTv3b data, For all the BEST Fans. The I compared the Houghton land use impact on CO2 to the NCDC Extended Reconstructed Sea Surface Temperature ERSSTv3b) with the land only data sets to show how land amplification tends to over enhance more than just CO2 forcing. A large portion of the land use amplification would be related to changes in the soil moisture/hydrology cycle which is more related to the land Tmin data than Tmax data.
In the United States where both the temperature and land use data appear to be more complete, there is a nice fit with the expected 15 year lag for nominal soil degradation.
Land use impact on diurnal temperature also does clearly indicate impact of actual temperature range or the impact on the temperature measurements, Suburban Heat Island Effect is likely a good description, since many of the temperature stations are rural but located near smaller community centers and airports. Unless this puzzle can be solved reasonably, even this quick illustration of land use impact on land surface temperature data should be enough to question how much of the "Global" land amplification should be considered when estimating "Global" warming.
It is also not very comforting that all the models and creative multiple linear regressions used to "show" alarming amounts anthropogenic change didn't notice that diurnal temperature range has not been following CO2 forcing but "Green Revolution" forcing. Imagine that?
Update: Comparing the Northern higher latitude land use, US, Canada, China and the former USSR to the difference between the NH SST and BEST also shows an interesting correlation.