Pre-1920 is roughly in-line with average, 1920-1970 looks to be above average but could be argued to be within normal range of variation, post-1970 is clearly above normal range of variation.
Your concern seems to be (1) that there is some negative connotation to the word "anomaly", (2) that the chart labels small differences anomalies rather than just large differences, despite small differences being possibly within a natural range of variation, and (3) that a baseline has been arbitrarily and improperly chosen.
These are all non-issues. The word "anomaly" as used here is clearly defined, and means deviation from a baseline. It is not being used in a pejorative or leading sense. In any case, the data is clear - there is a larger deviation towards higher temperatures, over many years, without historic precedent.
What you call an arbitrary average is not arbitrary. It is chosen for a clear reason - the temperature rise is due to industrial emissions which did not exist prior to the period covered by this chart, and at that point global temperatures were more stable than they are now by around an order of magnitude.
Nobody should be confused or misled by the use of the word anomaly here. The context is obvious to anyone paying attention to the science. I doubt you're confused by the data as presented, so I really don't understand why you're concerned about the title.
If it helps, think of the chart as showing which years actually are "anomalies". You seem to have a vague definition of an "anomaly" as something like a significantly large change from a specific average - presumably the temperatures over the last 1000 years would be sufficient.
I feel like you're expecting this chart to show more than it does, it's really very simple, and in no way misleading.
"In any case, the data is clear - there is a larger deviation towards higher temperatures, over many years, without historic precedent."
Except you also seem to misunderstand the use of the word, as it is completely unrelated to there being a "deviation towards higher temperatures". At most you could argue that it doesn't matter if people misunderstand it, as there happens to actually be an "anomaly" anyway.
About the reference time frame - I think things were going on before, like mini ice ages and what not. However I merely wanted to point out that the timeframe is arbitrarily chosen, not that it is necessarily a bad choice. In combination with the word "anomaly" it becomes more questionable as it kind of implies that those 10 years were "normal".
Again - it's not arbitrary! It's chosen because industrial emissions have affected the climate. There is a very clear reason why it was chosen. That's why we use the word anomaly too - it isn't chance!
Are you trying to say that it's not an anomaly at the beginning of the period in the chart when the delta is negative? I already granted that point but it doesn't matter because everybody already knows there is an actual anomaly due to industrial emissions! The "implication" that the 10 years were "normal" is not questionable because the temperature was normal before! This case doesn't need to be made here because it's been made by a global coalition of governments and scientists in exhaustive detail.
From Wikipedia on mini ice age:
"...a multi-centennial period of relatively low temperature beginning around the 15th century, with GMST averaging –0.03 [–0.30 to 0.06] °C between 1450 and 1850 relative to 1850–1900."
This is within the annual variation I was suggesting and is not comparable to what we see today. It's irrelevant.
"There is a very clear reason why it was chosen. That's why we use the word anomaly too - it isn't chance!"
So it is propaganda. The official definition of temperature anomaly is just "distance to an average".
There was temperature variation before industrialization, for example mini ice ages, so simply showing there is a temperature difference to some small period of time in the 19th century is not sufficient to show there are "anomalies".
You're not reading what I said. I just responded on "mini ice ages" and you ignored it. It's clear why they are using that period, and is scientifically justified.
Propaganda is a pejorative term that you're not justifying the usage of, and I certainly don't agree with your usage here.
I don't know the etymology of anomaly, but I think it's a perfectly sensible usage.
You are avoiding the question of whether you think there is an anomaly, probably for the good reason that there clearly is one in the colloquial and scientific senses of the word.
The data and science are clear, and I don't think your professed confusion at the use of the word anomaly is in good faith.
If you don't think there's a problem to be addressed, then it's on you to show the data doesn't show an issue. Just making accusations of propaganda is not good enough.
Your concern seems to be (1) that there is some negative connotation to the word "anomaly", (2) that the chart labels small differences anomalies rather than just large differences, despite small differences being possibly within a natural range of variation, and (3) that a baseline has been arbitrarily and improperly chosen.
These are all non-issues. The word "anomaly" as used here is clearly defined, and means deviation from a baseline. It is not being used in a pejorative or leading sense. In any case, the data is clear - there is a larger deviation towards higher temperatures, over many years, without historic precedent.
What you call an arbitrary average is not arbitrary. It is chosen for a clear reason - the temperature rise is due to industrial emissions which did not exist prior to the period covered by this chart, and at that point global temperatures were more stable than they are now by around an order of magnitude.
Nobody should be confused or misled by the use of the word anomaly here. The context is obvious to anyone paying attention to the science. I doubt you're confused by the data as presented, so I really don't understand why you're concerned about the title.
If it helps, think of the chart as showing which years actually are "anomalies". You seem to have a vague definition of an "anomaly" as something like a significantly large change from a specific average - presumably the temperatures over the last 1000 years would be sufficient.
I feel like you're expecting this chart to show more than it does, it's really very simple, and in no way misleading.