Make you wonder about how you can compare readings from non-modern equipment… and tree rings … and ice cores … and stuff they just make up. There is zero scientific rigor in climatology.
They apply confirmation bias as a core principle.
Certainly true as it is now.
Read "The Deliberate Corruption of Climate Science" by the late Dr. Tim Ball. He was there and saw it all.
https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=dr.+tim+ball&crid=2O3Y5KF9L93CT&sprefix=dr.+tim+ball%2Caps%2C1483