zlacker

The goal is to estimate an "average temperature" for Earth. What does that even mean? Are we talking about the temperature of the ground, the temperature of air at 2 m above the surface, the temperature of the Earth 100 m above the surface? In this case it's something like the second example: 2 m above the surface.

How do you ideally compute this average? You take the simultaneous temperature measurement at every point on Earth and take the average. Obviously that is not possible.

What do you do instead? You put together temperature readings where they exist, satellite data, coupled with past data and behaviors to make an estimate for the average temperature. How else could you possibly do it.