There are many reasons to believe the temperature trend is much cooler than the corrupt figure given for surface data.
1. The data is massively adjusted (equivalent to all the warming since 1940)
2. The stations just happen to have been located conveniently on the edge of urban areas – the areas that were mist subject to changes in the 20th century as urban areas increased.
3. There is proven poor siting (which causes additional warming to rural). The problem here is that they turn a nod and a wink to poor sites that help increase the warming trend where a quality organisation would have dealt with them.
4. Then there is the multiple instances of site specific tampering with data – which looks like individuals changing sites to cause additional warming to everything above.
5. Then there is the oft change in methodologies to select those that show the highest warming.
6. Then there is the way they intentionally remove sites with a cooling trend from the data (possibly as part of 5).
7. There is the fact the temperatures are far from global with e.g. most of central S.America and Africa being missed out.
8. Then there is the fraudulent misuse of ocean temperature data (changing good data without a warming trend to fit bad data with a warming trend).
Here’s my #1: Average global surface temperature is a meaningless number and as such anomalies of such a number are of no scientific value.
My main reason “global surface temperature” as measured by the Government agencies is crap — is that it is a massive fraud. It would be very, very hard to measure the temperature of the planet’s surface if one was honestly trying, but they are clearly not honestly trying to come up with the average temperature.
My second reason it is crap is that it is meaningless. The one number “average temperature” even if we could calculate it is not very meaningful anyway.
Calling it “global” surface temperature is misleading, because it’s mostly the temperature of the surface around urban areas, … and *not deserts, rural or wilderness areas, Arctic, Antarctic, mountains, large lakes, and also not the 71% of the Earth’s surface that is ocean.
We know we have Ice Ages and Interglacial warm periods. We also know that the warm cycles are far shorter than the cold cycles. We also know these warm cycles start during the coldest parts of the cold cycles.
We also know these warm cycles are very sudden and when they end, it is like dropping off a cliff.
The belief that some CO2 might stop all this is insanity. We still don’t understand why our planet decided to suffer these cycles which are a geologically recent development.