re: Current idea that cold is from global warming fundamentally flawed?

It's not a lie that global warming can cause a sudden onset of cold climate.

It is a geological fact.

I'm not well versed on the polar vortex, but I have thoroughly studied Ice Age climates. Studying paleoecology is a hobby of mine.

Toward the end of the last Ice Age, natural forcing caused average annual temperatures to rise suddenly. This caused rapid melting of glacial ice. This cold meltwater became locked behind giant ice dams. When thes ice dams burst, billions of gallons of cold freshwater plus ice bergs and rafted debris flooded into the North Atlantic. This huge amount of cold freshwater shut down thermohaline circulation--the ocean currents that moderate climates.

This caused a sudden drop in worldwide average annual temperatures precipitating a 1500 year cold snap known as the Younger Dryas--it became as cold as the Ice Age again.

This cyclical event has occurred multiple times over the last 7 millions years, but especially over the last 2.4 million years. It happens more frequently and with greater intensity during Ice Ages.

There is abundant geological evidence of these events, known as Heinrich Events. At the bottom of the ocean there are rocks called dropstones and lots of debris including fossil trees that were carried out to sea by these floods. There are even visible drag marks off the coast of South Carolina where icebergs half ran aground on the ocean bottom.