So, to get an average value from a set, one must divide the sum of the values of the set by the number of parts in the set. That is to say we have a set which have the values of 2, 4, 6, 3, and 5. Let’s call this our global warming average. The sum of the set is 20, so, we divide it by 5. So, the average is 4. This is the average for this set.
Let’s say the values of this set didn’t change very much for several years.
Then, let’s say, for some reason or another, we no longer know the value of one of the parts of the set. Now, the set is 2, 4, 3, and 5. We don’t know what the part which used to be 6 is, today. It’s probably 8, so, we’ll just call it 8 and pronounce this as fact. So, it’s 2,4,8,3, and 5. So, the new sum is now 22 and the average is 4.5. Because, well, it was probably 8.
Let’s also say, we knew what the values were of 2, 4, 6, and 3, but not 5 for very long. For the one that was 5, we don’t really have a very long history. But, we’re pretty sure it was 3 for many years prior to us knowing what it was. So, we believe what was 2, 4, 6, 3, and 5 was 2, 4, 6, 3, and 3 for a time before we really knew. So, the sum was 18, or an average of 3.5.
Using a 4th order polynomial, it looks like this on a graph.
A ten year mean of GISS’s temperature data looks like this.
And, people believe this crap to be true. You can’t make this stuff up. 6th graders should know better than that. But, our really science people, and really mathy pretend skeptics don’t.