You’re floundering on a frozen snowfield while your crampons sit forlorn and forgotten on the credenza at home. If you encounter steep snow or icy trails without crampons, it’s best to turn back or find another way.
But if quitting isn’t an option, you can increase traction on snow and ice by embedding nails or screws in your boot treads. If you’re loathe to perforate the soles, drive the screws through a thin plank of wood or bark, and secure one plank to each foot with straps or duct tape.
Since most hikers don’t pack extra screws, you might be able to scavenge them from a miner’s cabin or fence. Strands of barbed wire, rusty mattress springs (stretched flush against the sole and over the sides), and shredded aluminum-can bottoms also work.
A less effective but more widely available approach is to wrap a densely knotted rope around the bottom of your shoes, like tire chains. Polar explorer Ranulph Fiennes depended on this approach while descending the Beardmore Glacier during his successful 1992-93 Antarctic crossing.