I'm saying that the way they have to correlate the old temperature is like this
(a) you get the weather stations that are 100 years, old, you look at the data (b) you compare it to the same data as today
But there is a problem, all these old weather stations are now surrounded by buildings, aircon outlets everything. Some are in the middle of concrete where before they were in the a grass paddock, but as population increases urbanisation changes around it.
You have to compare the old ones, problem is the micro climate around them has changed
Watch the video links, it shows some in the USA and how a lot of the station's increase in temperature can be attributed to urbanisation or having to be moved since something wants to be built there then put in a totally inappropriate place.
