@
DogMan says
1909-1910 – Amundsen sailed an ice-free NW Passage
Amundsen was a brave heroic man. However, we don't have to depend on two years of local arctic observations. We have
eight hundred thousand years of climate data to work with, covering about 7 ice ages. The climate data comes from bubbles in glacial ice, and is corroborated by data from lake & sea floor sediments.
https://icecores.org/about-ice-cores
CO2 & methane & temp data
Here's
where the various data sets were collected:
The most salient thing about the 800,000 years of climate data is the rate of change during those previous 7 ice ages compared to the current rate of change this century.
The data is fed into supercomputer numerical models. The models can be trained on some of the seven ice ages and tested on others. Here's a very out-of-date model just to give you a sense of what they're like and how many climate variables are involved.
http://web.mit.edu/globalchange/www/climate.html
P.S. Some may ask where does the money for climate research come from?
Fair question - it comes mostly from the National Science Foundation. Equally fair: where does the money for climate denial come from? The US oil industry makes about $110
billion per year; coal another $20 billion. Big Oil spends $3.6 billion per year on advertising; a sum equal to about 8X the whole NSF climate budget. You're not naive enough to believe
none of that money goes to propaganda, are you?
