by PJ Michaels and R Maue, November 23, 2017 in WUWT

Let’s face it, global surface temperature histories measured by thermometers are a mess. Recording stations come on-and offline seemingly at random. The time of day when the high and low temperatures for the previous 24 hours are recorded varies, often changing at the same station. Local conditions can bias temperatures. And the “urban heat island” can artificially warm readings with population levels as low as 2500. Neighboring reporting stations can diverge significantly from each other.