> "Impossible" seems like a bit too strong of a statement.

You might be right. Rather than a statement of fact, this is my opinion based on some four decades in engineering spanning a range from consumer to military/aerospace work. The measurements taken as factual in these models, from my perspective, defy what is possible across 150 years around the planet.

If you read through descriptions of the methodology you come across passages with a summary that looks like "average of the average of the average of the average". You can't just keep doing this without suffering a loss in significant figures. You would literally have to have accuracy and precision information on each sensor and for each measurement to then be able to propagate all of this carefully. Furthermore, you really need to know the standard deviation in order to understand the uncertainty in the measurements.

If we have a set of measurements in region 1 and the average uncertainty in the measurements is 0.5, while, in region 2, it is 0.3...what should this mean when you combine them with other regions in order to fabricate (because it is being fabricated through computation) a number to represent the entire northern hemisphere. To that point: A number representing an entire region, state, country, continent or hemisphere MUST HAVE an uncertainty attached to it. There is no such thing as "The northern hemisphere is at 18.2 degrees", that would be a silly statement to make.

Anyhow, I don't want to beat this one to death. Nothing is going to change. I just feel very uneasy with the way some of this data is presented. I can't remember ever seeing these presentations with a statement that quantifies the uncertainty in the numbers. When you do that, it is easy for the audience --particularly if they have no relevant training-- to assume the numbers given are an accurate and precise rendition of some measurement, when, in fact, that is never the case.

What would the graph presented in the article look like with error bands? Don't know.

An example of this is the typical graph for global air temperature that shows-up for most searches [0]. Not only does this not have any indication of measurement and propagated errors, it also resorts to calculating the temperature anomaly with respect to the average from 1961 onward rather than the entire period. Th graph would look very different if the average from 18xx onward was used. In fact, we would likely have to explain why and how everything from the 1920's and beyond is red.

You will occasionally find graphs that do seem to compare to the average of all data [1]. This one, of course, looks a lot less "violent" than the other presentation. Using a late average pushes 75% of the graph into "it was cold" territory and makes it look like things went to hell after about 1980. One should not be blamed for thinking that one approach fits a desired narrative far better than the other.

Anyhow, not sure what else to say. I am not convinced I am right. In order to get there I would have to do weeks of work reverse engineering the data and methodologies. No point in doing that. I am naturally very skeptical --which, I think, is a good thing-- so I'll stick to not being happy with the way things have been presented so far and hope to find something better in the future.

[0] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/gl...

[1] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/te...