We’ve seen this kind of graph many times over the last dozen+ years. Usually just with one data set, such as RSS. In this case it is comparing two data sets. GIStemp and RSS. This graph was used on WUWT to show that there is a strong divergence between RSS and GIStemp in the recent years, and to ask why. In most cases, it is to show that for about the last 18+ years the trend in satellite data is nil. No warming. In all these cases, the stress is on the trend.
The whole discussion on these kinds of graphs revolves around 1/10 ths of degrees of trend. Even in the end bit where they are looking at exaggerated trends from short periods of time, it’s down in the 1/10 C range. (At least, I assume it is in C ).
What I want to point out is that the range is over 5/10 degree (actually I eyeball it as about 8/10 at the max range) and that this range happens in a few bursts about every 2 years.
Now when I look at that, and realize that CO2 levels are nearly constant over a 5 to 10 year period, it is incredibly obvious to me that something else is causing the changes in the values. If something else is swinging this cat by 5/10 to 8/10 of a degree in 2 years, just how in the world can someone assert that the ‘trend’ comes from nearly constant CO2? CO2 must be in the error band of swings from the major driver. IMHO, this matters.
Until the major drivers are clearly identified, their error bands identified to greater precision that CO2 changes, and that major driver subtracted from the raw data, you can say nothing about the other drivers of those temperature changes, and nothing about their “trends” from those alternative explanations.
A trend much much less than a range is likely an error in starting and ending points, or random variations in the range over time, than some other much more minor contributor.
IMHO, this would benefit from a formal treatment by a Ph.D. statistician.