Real fur is a renewable resource. Synthetics often require petroleum based products which as we know are non-renewable and create significant amounts of pollution. Animals don't need to be farmed for their fur, they can be hunted/trapped which Ontario law requires the meat is not allowed to spoil. Even farms don't waste the carcass after the fur is removed, they are sent to rendering plants to be used in dog food etc. Personally I say to each there own, but there is a lot of misinformation when it comes to the fur industry.
Biodegradeable polymers have been round for donkey's years. This needn't be an issue. I don't think special forces use fur on any garments and they need to cope with extreme conditions. There's plenty of alternatives that don't involve what really amounts to animal cruelty. If I can avoid it and it's not necessary for the function of the article I'm kind of confused why anyone would actually choose to go for the crueler option. I just bought myself a parka that was on sale, original price was about that of a Canada Goose jacket and the thing is incredibly warm. It has synthetic fur trim and supposedly ethically sourced down filling.