what I read is that the great hockey stick graph produced about 1998 that shows global temperatures warming and carbon dioxide level rising from 1820 onward...
the data set that produced that graph consisted of 12 trees cherry picked from a group of 32 trees in siberia.
those data sets have since been destroyed. when larger samplings have been tested ... they show no such hockey stick leap since 1820—when sampled in the context of the last 1000 years. Which includes both the big warm period of the medieval and the big cooling period of the little ice age.
If you sample the last 100,000 years. we’re in an extended interglacial warming spell and overdue for a temperature snap...downward.
The global warming crowd was a global cooling crowd until the early 80’s.
That's why they now call it "global climate change" and cover themselves forever trying to hold the temperatures the way the were in 1820.