Hypothermia sucks! End of story. It is even worse when you are stuck on the face of a mountain with absolutely no where to hide from the cold. American Alpine Institute had a hypothermia post which was drawn from a NOLS hypothermia post. (AAI) (NOLS)
Apparently the best way to treat backcountry hypothermia to try to rig a hyporthermia burrito wrap made out of three sleeping bags, two sleeping pads and a tarp. Picture below courtesy of NOLS:
Now I don’t know about you but I don’t carry that much stuff when I’m climbing.
If the shit hits the fan and I need to make an unplanned bivy in chilly weather this is what I do after I find a decent bivy site that is sheltered from the wind. I set up my rope as a makeshift sleeping pad/seat, I put on every piece of clothing I brought, I put my feet inside my backpack straps into the snow and I focus on the saying, “it doesn’t have to be fun to be fun”.
I also usually climb with a Cilogear Worksack backpack which has a removable bivy pad. I’m not sure why all backpacks don’t work in a bivy pad but I’m sure as hell glad the Graham at Cilogear figured it out.
BTW, if you are reading this Graham, your packs rock and I would be more than happy to be paid to say that!