As I understand it, the amount of carbon in the atmosphere has not remained constant. Radiometric dating depends on a constant rate.
The historic changes in atmospheric 14C are known and have been used to calibrate radiocarbon dating.
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I have to confess I still donāt see the relation to creationism? I gather you might be thinking of the methods by which it is established that the Earth is much older than the ~6000 years typically argued by YECs(?), but the Earthās age isnāt established by Carbon dating.
Carbon dating is used on things at most 50.000 years old*, after which methods that are entirely unrelated to carbon are used instead. So even if rising atmospheric CO2 levels makes it difficult to do accurate carbon dating, it has essentially no bearing on the case for our planet and lifeās full age.
*And Earth is thought to be approximately 4.56 billion yo.
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yeah, I think Swamidass asked me about this and gave me a link to varves. They use tree rings and varves to calibrate. I looked up varves some more and found a basic video that explained they actually counted varves using radiometric dating, so to me, itās a circular argument.
Except that isnāt true. Why not read the article linked you to?
They also use tree rings which are manually counted (i.e. dendrochronology).
That is all beside the point, as @Rumraket mentions. No one uses radiocarbon dating to measure the age of the Earth or fossils older than 50,000 years old.
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I read the article. Then I wanted to look it up some more and found a YouTube video that said they used radiometric dating to make sure they were counting varves correctly. I could be understanding the video wrong. I had linked it for you.
They can do it both ways @thoughtful. It says something important that you get the same result both ways.
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Only if varves are independently counted. If they said, we counted all these varves, hereās how old the earth is. And then radiometric dated the organism found in a specific age layer and said, the radiometric dating match the layer. Or if they radiometric dated an organism, and then said, it must have been found in this layer. And then if they were correct thatād be cool. But I understood the video to be saying that that radiometric dated an organism to find out what layer they were working with, so that could calculate all nearby layers. Thatās a circular argument.
They are independently counted till you get to about 50,000 years ago.
No one says this. The earth is older than the varves.
It isnāt circular of if you already demonstrated by independent means (counting varves) that this approach works and is an accurate shortcut. Thatās the situation here.
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Tree rings are independently counted and are rooted to the present day.
https://c14.arch.ox.ac.uk/calibration.html#tree_rings
No one says that. The age of the Earth is not determined by carbon dating.
Youāre right. I had forgotten how many varves they said they counted. From an evolutionary standpoint, my comment made no sense.
What do you understand him saying from about 6-7 minutes here? https://www.youtube.com/watch?v=0ERsk_J6gn8 at 6:15 heās talking about āsignificant inaccuracyā and then goes onto to say they radiocarbon dated to fix the inaccuracy. At 3 minutes the video talks about putting 4 samples together. But thatās also a subjective process. If the one varve sample cannot be extracted and independently counted, and matched with another sample independently counted, I donāt see how this is worth relying on.
Why donāt you look at the data yourself and see if you can see that supposed problem? Did you read the article I directed you to? I had data in it.
Iām not the one trying to convince others that evolution is true. I had read the article. If there seem to be basic flaws Iām not going to waste my time.
Iām not trying to convince you evolution is true 
. I thought you were asking because you wants to see and understand for yourself. If you donāt want to look at the details, probably not a good idea to disparage someone elseās work thoughā¦
I think weāre possibly having a communication issue. Iām trying to say that I read the paper, and it looked like a really good explanation of why carbon dating can be trustworthy because it relies on something else - varves. Then I went to research varves, and to me, it didnāt look like good science. So I donāt understand why you want me to go digging back into the paper. If it answers why the varve science is good, fine - but why not just point that section out to me directly? Iām not a scientist. I can only understand these things generally, not at a data level, and I donāt really need to both defend creationism and evolution. 
It felt like you were being condescending.
Okay, here you go. In response to this issue:
So here is the data I was referring to in this article (Lake Suigetsu and the 60,000 Year Varve Chronology ā Naturalis Historia):
The graph above is a summary of comparison of carbon-14 activity with tree rings and with lake varves from Lake Steel in Minnesota and Lake Suigetsu in Japan. It was prepared by geologists Davidson and Wolgemuth. Notice that as one moves deeper into the sediments of a lake (varve data) that the total amount of C14 gradually declines. There is no abrupt break in C14 concentrations suggestive of large changes in radioactivity in the past as predicted by some young-earth creationists.
Notice that this graph was produced by counting layers, and then measuring C14 levels at different layers.
Letās interpret it together.
Do you see any patterns in those dots?
Do you see any deviations from that pattern? How large are the deviations?
Does the pattern of the blue (tree) dots match the pattern of the yellow (varve) dots? How are they they same? How are they different?
I guess perhaps Iām still not being clear. We could discuss these questions, but my point is whether these questions can even be discussed. For example, you did not move on to consider Jeansonās historical claims about his y-chromosome clock because you decided it was bad science. If that particular video indicates there isnāt one continuous core sample, and seems to say there were discrepancies so they used a circular arguments and I havenāt seen a claim that there is a continuous core sample, and no oneās shared the underlying data that shows they did not use a circular argument, why should I consider the questions the research poses if the science itself is bad? You pointing me back to an article that assumes the science is good, doesnāt prove to me that the science isnāt bad.
Keep Jeanson out of it. Thatās a different issueā¦
Because the science is not bad.
There are several overlapping samples that can be aligned with one another. There are several continguous samples from the same hole, coming out one after another.
Do you really mean to argue it isnāt possible to count layers in a lake?
The lake sediment is hundreds of meters deep. Do you really mean to argue that we canāt plausibly count laters in sections pulled from the same hole, but need all those sections to be unbroken? That doesnāt make sense, does it?
How would you try to count these layers?
I just did share exactly this data. Can you show me how this data is circular? They counted layers. Independently, they measured C14 levels in each layer. They plotted these on a semilog graph and saw a straight line. The layer count was not used to infer the C14 level. The C14 level was not used to infer the layer count.
Where is the circularity? Can you please spell it out for us?
C14 dating depends on a constant decay rate, not on a constant C14/C12 ratio in the atmosphere. It is well known the C14/C12 ratio has varied over time which is why C14 dating is calibrate by over a dozen independent yearly dating proxies.
INTCAL13 AND MARINE13 RADIOCARBON AGE CALIBRATION CURVES 0 ā 50,000 YEARS CAL BP
C14 dates are not just compared to Lake Suigetsu varves but to multiple lake varve sets, multiple tree ring data sets (dendrochronology), multiple ice core yearly deposits, multiple ocean core yearly sediment deposits, multiple yearly stalactite and stalagmite growth bands (speleothems), multiple yearly coral growth band data sets. All that independent data produces the calibration chart shown above. Creationists will think of a hand wave for each individual data set but can never explain why so many independent data sets show such close consilience. 
Note the IntCal13 calibration results are due to be replaced by an even more accurate calibration, IntCal20, which has over twice the number of calibration points. The publication of the Intcal20 data is unfortunately being delayed by the same COVID mess which has bitten us all. 
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