Silk might do a little to keep warm but its really not that great in comparison to a scarf or stole made of authentic kashmir pashmina. This material has the best natural insulating properties found on earth and comes only from the capra hircus mountain goat that lives in brutal conditions 14,000 feet above sea level in the Himalayan mountains. Its really expensive however. If money is no object and we are talking survival, i think this would be the best material. Another good thing about it is that it is so fine woman often scrunch them up and put them in there purse, so they take up very little space. Many people sell scarves and call it pashmina although it is really not. You have to be sure its authentic capra hircus pashmina and check the percentage of the content. Its sold in different plys (thickness) although its not really important because you would be wrapping it a few times around your neck anyway. Here is an article link i wrote for anybody interested. Capra Hircus Pashmina
Anyway, there are more articles that get into this materials properties in greater depth and how it relates to moisture but i don't have those links. I sell 100% capra hircus items on a custom ordered basis only on this website 100% pure capra hircus pashmina wraps. They are available in 80% pure as well, although i don't have them listed. 80% is also cheaper. Like i said, its much better than silk but very expensive stuff. I would only recommend it if you were going on some sort of live threatening adventure in extremely cold climates. Just thought this information might be useful to somebody.