A lot of engineers are skeptical about the purported average global temperature because of the way it is computed from a very small set of temperature measurements that are of considerable individual uncertainty. The idea that this global average temperature could be computed with an accuracy of 0.1 degree is impossible to believe. Here is an article by an engineer about how the global average temperature is divined by the climatologists at Hadley CRU. Like the engineer who wrote the article, I also did climate models, in my case including for the Apollo Command Module and the Lunar Module. In those cases we had the advantage of being able to do extensive testing, something the earth climate modelers can't do.