[kkjjkgjjgg]

As I said - the issue I have that a year having a different temperature from the average of some timeframe is not actually "anomal". It is to be expected. It would in fact be weird in most cases if temperature would be exactly like the average.

So calling any difference to the average an "anomaly" seems misleading to me.

The trend of rising temperature may still be "anomal", but that is not what they are referring to.

Your explanation kind of points out the problem, as you also seem to think a "deviation from the norm" is somehow unusual.

If you look at another example, it should be obvious: take the average temperature throughout one year, then plot the "anomaly" of daily temperatures in that year against the average temperature of the year. Then in summer it would be "anomaly hot" and in winter it would be "anomaly cold". Except it wouldn't actually be anomal to be hotter in summer and colder in winter at all.

[ximeng]

I’m guessing English isn’t your first language by your use of the word “anomal” - which doesn’t mean what you think it does. This may be contributing to your confusion.

https://xkcd.com/1732/ Suggests the fastest temperature change in last 20k years is around 1 deg c in a 1000 years. The graph linked here shows 1 deg c in around 50 years.

Annual variation is up to 0.3 deg c, mostly less, from eyeballing the graph data. If you’re suggesting that there is a reason we shouldn’t call a 1 deg c plus change an anomaly, you should really just say what that is, just like you have for winter and summer which nobody would call an anomaly.

[kkjjkgjjgg]

The chart is a chart of the yearly "anomaly". So even a 0.3 degree deviation is plotted in the chart as an "anomaly". Clearly you don't understand the issue, which is exactly my point. It is a misleading label.

I am not saying the rise by whatever many degrees is not an anomaly. That is simply not what they plot. They don't call the steep rise an anomaly, they call every deviation from the arbitrary average an anomaly. They don't plot the "steepness of the rise", although you can see it in the chart. Every point in the plot is called an "anomaly", not the plot as a whole. Even the data points where a year is colder than their arbitrary average is called an anomaly in their chart.

English is not my first language but I think I know what an anomaly is supposed to be.

[jiddu]

I think I understand your issue.

The term 'temperature anomaly' has come to mean: A temperature anomaly is the departure from the average temperature, positive or negative, over a certain period (day, week, month or year).

If I look up 'anomaly' in a dictionary: a person or thing that is different from what is usual, or not in agreement with something else and therefore not satisfactory

The word anomaly is only used for unusual/unexpected things. Where in the scientific world the term temperature anomaly doesn't have to be used for unusual and unexpected things. For example a temperature anomaly of 0, which isn't unusual or unexpected at all, is still a valid temperature anomaly. However, you would never use the dictionary meaning to classify the 0 as an anomaly.

Maybe it feels more neutral to use a term like temperature deviation or delta.

I don't know who initially came up with the term temperature anomaly and what their intend was, so I won't blame anyone of propaganda.

The temperature rise since pre-industrial times as a whole is generally considered an actual anomalous situation, so it seems fine to keep using the term temperature anomaly in this case.

[kkjjkgjjgg]

Yes - I know it is technically the correct term. If you look it up on Wikipedia, you get the proper definition. But for people not in the field it suggests something different than it actually shows - even though by chance there is also an actual "anomaly" in the form of the rising temperature trend.

[ximeng]

You're really straining for this point - nobody is going to be confused by the use of the word anomaly. It is not "chance" that there is an actual anomaly, that's the reason the terminology is being used.

If they'd used the word "deviation" would you have been happy? Or is your real objection to the use of the word "anomaly" to describe temperature deviations in science generally?

[kkjjkgjjgg]

Yes I would have been happy with the word deviation. The discussion here has shown that many people misunderstand the use of the word anomaly.

I don't know what you mean by "it is not chance that there is an actual anomaly".

As for "straining the point" - well I made the point, people responded, and I responded again.

[ximeng]

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.

[kkjjkgjjgg]

"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".

[ximeng]

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.

[kkjjkgjjgg]

"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".