Spymaster
Plastic Paddy
To be fair...if we enter an ice age, a sheepskin coat would be the penultimate best coat for staying warm...and dry.
The absolute best would be fur.... I am whispering that though...
I might have agreed 20/30 years ago but modern materials do a far better job of keeping you warm and dry nowadays with a fraction of the weight and volume. Layers are where it's at. A decent base, fleece, down jacket, and hardshell, will see you right from India to the Arctic.