# Verification statistic for ice core temperature reconstructions

1 Do ice core temperature reconstruction studies have a calibration step, or is the relationship between Oxygen-18 and mean global temperature considered linear enough that this is not required?

2 Irrespective of whether calibration is used or not, do ice core reconstruction studies supply a verification statistic (R-square) against the instrumental temperature record?

Please could you point me to any papers containing these statistics

On the temperature calculation using the 18O isotopes: Calibration: The samples are always plotted against the VSMOW (Vienna Standard Mean Ocean Water) which is always 0 permil.

Info: We calibrate every Sample against recent ocean water Oxygen-18. 18O concentrations in the sample similar to the ocean water have a 18O signature about 0 permil

The temperatures can be calculated according to the equations (in high latitudes):

$$\delta^{18}\textrm{O} = (0.521 \pm 0.014)t_a - (14.96 \pm 0.21)^0\!\!/\!_{00}$$

For further information: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/isotopic-fractionation

It is a lovely introduction to this highly interesting topic! Keep interested in this topic!

• Thank you, this is very helpful! Would you have some moments to expand with a little more detail, as I am a novice in this area? Eg what does 0 permil mean? And why high latitudes? Jul 26, 2022 at 14:14
• Hi I hope it is more clear now! Jul 27, 2022 at 7:51
• Thank you very much! Jul 27, 2022 at 9:28
• You are welcome! If you have any outher questions to 18O, please ask! It is a highly interesting topic and a nice tool to determine earth systems (recent and palaeo) Jul 27, 2022 at 9:47