Massive urbanization has done a remarkable job in warming the thermometers; the biggest problem to measuring the free atmosphere is that there is no place representative of the entire column average.
If only we could find the Earth’s rectum, then we could easily measure it’s temperature. Since the heat capacity of the atmosphere is not all that much compared to the oceans, this whole discussion of the Earth’s temperature is fairly bogus to begin with. That’s why I’d like the genius “Climate Scientists” to agree to a more rigorous system definition. Otherwise it is just more Hope and Change all over again.