[empath75]

> If the average global temp used to be claimed to be 15C but since 2000, they claim it was 14C, then somebody is making false claims about the avg temp.

You get different baseline body temperatures depending on whether you use an oral thermometer or one of those infrared thermometers you put in the ear, but you'll both be able to detect a fever -- it's higher than it would normally be with that thermometer.

There are many ways of measuring the average temperature of the planet, and they will return different results today, tomorrow and yesterday -- but if you use the same method across time, all of them should agree on whether the planet is warming or cooling over all. One might say it was 15 in the 60s and 16 today, another might say that it was 14 in the 60s and 15 today -- they both agree the planet has warmed by a degree, though.

It's easy to go through several decades of stories on climate and cherry pick measurements from different news stories to make it look like the numbers are all over the place, but you have to compare measurements from a single source using a single method.

[jansan]

Your analogy with the thermometer does not work. If you use rectal or oral measurement you will be able to detect fever, because temperature fluctuation at these locations is low if the person is healthy. With global temperatures this is different. Fluctuation is very high (for example there was snow in Cairo in 2013, but we did not have an ice age then).

Therefore you need to cover many locations, and that's the problem. Global temperature data is not very good for the first half of the 20th century.