No they picked a certain time frame and compare to the average temperature of that time frame. Nothing more, nothing less. I think the reference time frame is some 20 year period in the end of 20th century, but not sure if I remember it correctly.
What is the Yearly Average Temperature Anomaly?
It is the difference between the average yearly global surface temperature and its pre-industrial baseline. The pre-industrial baseline is calculated as the average temperature from 1850 till 1900. The value for the current year is actually the average for the last 12 months, for example in June we include values since the previous July.
I really don't understand what your issue is with the terminology. Are you suggesting there is no change from the norm? Propaganda as in there is a political agenda to presenting this data? Would that be that the data is wrong, if so on what basis? Or that the data is irrelevant and it is being presented as relevant?
Global temperature changes seems very relevant to me. This site is also just presenting data, the language is pretty neutral and in line with the common use of anomaly ("something that deviates from what is standard, normal, or expected") given the baseline they have stated, as well as the wikipedia article you link. The main issue I see from the wikipedia article is that these are not "standardised anomalies" - but the site is not claiming to provide these.
If your argument were that they should provide more data I could see that, although it's marked as version 0.1 so perhaps that's a bit harsh. If it's just that they're using the wrong word, then that's not very compelling to me.
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.
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.
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.
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.
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?
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.
By saying it is not chance I mean that the word "anomaly" is used because there is an anomaly. That's what appears to be confusing you, that you feel this word is being picked to imply something about the science, when in fact the causality is the other way around. The science has shown there to be an anomaly and the word has been used because there is an anomaly. The fact that it is less relevant pre-1920 is not important because people care about climate risks now when there is a clear anomaly shown in the data. You're focusing on something utterly unimportant.
For comparison, again, consider the average temperatures within a year, and then the daily temperatures are an "anomaly" and summer and winter would be anomaly because their temperatures deviate from the average. You wouldn't say "science has shown that summer and winter are an anomaly".
Anomaly is used because this is a new phenomenon due to human actions. You have no apparent concern about this but are just worrying about word usage.
Why do you think that the word temperature anomaly is used in climate science? The important issue is the global risk not your carping about the terminology.
No you are wrong. That is exactly the issue. It is not used because it is a new phenomenon due to human action. It is simply a technical term meaning different to some average. That is why it would also be used in a chart of temperatures throughout the year.
You demonstrate the issue very well. However, I give up convincing you, as clearly you won't understand it for some reason.
"Why do you think that the word temperature anomaly is used in climate science? The important issue is the global risk not your carping about the terminology."
So you admit it is being used for propaganda, not for scientific reasons. Exactly what I am concerned about.
I don't think you're confused about the data. I don't think I'm confused about the data. I don't think anyone is confused about the data.
To me the important thing is the data, I don't care if they call it "burning hot death" in the chart. You're focusing on a word that I don't care about, and that is used in accordance with its technical meaning. And you're ignoring the data and distracting from the issue it represents.
To convince me I'm wrong on the usage of the word anomaly - please find the etymology of this word as used here - I had a look and couldn't, but don't really think it matters enough to search for why this word was used in the first place.
But really, I think you're deliberately trying to detract from what the data shows by focusing on something irrelevant.
Intentionally misleading communication is propaganda.
If you think you understand the chart, tell me what would a year with "normal" temperatures look like? What would be a normal temperature?
I said here that the pre-1920 period, which is relatively flat (within a variation of around +/-0.5 deg C), represents years with normal temperatures:
https://news.ycombinator.com/item?id=29309923
I'd say anything outside of +/-1 deg C from that average would not be "normal", and would need need an explanation. I'm not an expert though, but eyeballing the data that looks reasonable to me. I have already said this though, so not quite sure why you're asking me again.
I also don't see this as misleading ("intentionally misleading communication") - are you saying there is not an "anomaly"? That there is no climate change? Or that any climate change is within normal variation, that is, not affected by industrial emissions?
The example you give of summer and winter having different temperatures is obviously not relevant to climate change as presented here. The "little ice age" has a scale and speed of change not comparable to what is presented here, as I've already mentioned.
Given all this I don't understand how you can think there is no anomaly. It is even less clear to me how you would conclude this was intentionally misleading when it seems totally reasonable to label this an anomaly based on the data and the science behind it, which you seem to be ignoring or disagreeing with.
I mean... they even have a chart of average temperatures going back to 1850, so it's not like they're hiding their data.
I guess you might be arguing that by calling it an "anomaly" they are making an assumption on the science that isn't justified by the chart. But the whole existence of this site is clearly premised on climate change being an issue, so the causality is the other way round. The site provides a simplified visualisation of data that shows what people have concluded through exhaustive scientific analysis.
The exhaustive scientific analysis provides the justification for the anomaly, this site shows this data in a way that's easy to digest. You shouldn't be looking at this data in isolation and saying there is man-made climate change, you should be looking at this site as a starting point to review more research and understand why this data that looks concerning is in actual fact really concerning.
If the scientific literature was in any was non-conclusive about whether there is genuine anthropogenic climate change, I'd have more sympathy to your point on whether using the word anomaly is appropriate or misleading. But you're not arguing the science, not even arguing the data, you're only arguing the word "anomaly", and for me that's such a long way from proving this to be propaganda that I don't feel you're arguing in good faith.
I am not at all concerned with the use of the word anomaly because I already am concerned about climate change. I'm assuming you're concerned about the use of this word because you're not concerned about climate change.
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.
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".
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.
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".
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.