So the answer is voodoo.

But recorded live data only goes back so so far. The rest is inferred data with an accuracy curve.

Its all Al Gore's fault too much hot air from his big stupid mouth

Between my Air Force & civilian careers, I made many trips to Thule Greenland between 1982 & 2014. I'm not a scientist or a tree hugging environmentalist, but the changes in the snow cap were obvious.
I've lived in Colorado since the early '70s and the weather changes are obvious over the years.

It's all that hot air coming from your posts.

Really? Here is the Vostok Ice Core graph with 450,000 years of "climate change". Explain the constant and rythmical climate variations you see over that time.

400,000 years? I remember it like it was yesterday. How are Fred and Wilma these days?

As I said in my post, I'm not a scientist. You tell me what it means.

Yaba daba doo! Always had a thing for Wilmer

Wilma. Does that mean you and Barney are no longer together?