[inigyou]

Yes there are. Scientists compare the measurements from both methods in the time when there's data from both. For example ice cores formed last decade should match direct temperature measurements from last decade. It's the same way the oldest rings from living trees are matched against the newest rings from tree fossils, and radiocarbon dating is checked against all of that.

[qsera]

That does not look very reliable to me, because that implies certain things are only affected by ambient temperature.

Btw, Can you tell me how ancient temperature is measured from ice cores? My lookup only says we can detect atmospheric composition, and not temperatures from the ice cores.

[TYPE_FASTER]

> Btw, Can you tell me how ancient temperature is measured from ice cores?

https://www.antarcticglaciers.org/glaciers-and-climate/ice-c...

[qsera]

>Past precipitation can be used to reconstruct past palaeoclimatic temperatures. δD and δ18O is related to surface temperature at middle and high latitudes. The relationship is consistent and linear over Antarctica[9]...

I think this is also flawed, because this computation requires the ratio of the isotopes in the atmosphere at the period of interest, which we don't have. And the people making this measurement just seem to assume it would certain value derived from the present, which is also unreliable...

So yea, all things considered, pretty unreliable..

[TYPE_FASTER]

https://science.nasa.gov/earth/earth-observatory/paleoclimat...

[qsera]

See, since it seems that you are convinced yourselves, can you tell me how accurately the past temperature can be assessed by using this method? I mean +/- how many degrees?

Also share if this accuracy requires any implicit assumptions. For example, "If we assume that X today is true then it is true back then as well" where X is not a physical constant...

[RetroTechie]

Air bubbles from ancient atmosphere caught in ice -> historic CO2 levels -> historic average global temps.

This is fairly 1:1 linkage, and the Earth-heating effect of atmospheric CO2 was established in what, early 20th century or so?

[qsera]

>historic CO2 levels -> historic average global temps

But this seems to imply that global temperatures are only dependent on CO2 levels. That is a pretty flawed assumption...

[RetroTechie]

No this is 'calibrated' against other research like fossils (indicating which species were living where & when) & probably more.

It's called science for a reason... (not back-of-a-napkin stuff)

[qsera]

But those are unreliable as well...

See, since it seems that you are convinced yourselves, can you tell me how accurately the past temperature can be assessed by using this method? I mean +/- how many degrees?

[inigyou]

Can you tell me any answer you'd accept?

[RetroTechie]

> But those are unreliable as well...

Can you tell me how many research papers on this specific subject you have read, before coming to that conclusion?

Hint: chances are you're correct (!). Size of the error bars, timeframe(s) talked about, how data was gathered, how results were processed etc, that is what such papers are about. Educate yourself! (Wikipedia is usually a good start)

[inigyou]

It seems like you're on the trajectory to refuting all historical measurements altogether. In that case, I can't help you. Good luck. I suggest the philosophy of Last Tuesdayism, it may interest you.

[qsera]

Not really.

I only reject using them for certain things that require vastly more reliable data. And I am not making the mistake of relying on unreliable data just because it is the best we can manage.

Also why don't you answer my question about ice cores?

[inigyou]

I'm not an ice core scientist. I suggest you ask them for detailed specifications. But the way you have posed the question strongly suggests that you will not be satisfied with any possible answer. Anything short of your eyes laying upon a thermometer will always be "not reliable enough", and thermometers only record the current temperature.

[qsera]

It is not really surprising that skeptics exist when the answers they get are of these sort...