If you attempt to move up a climbable surface without a climb speed, you expend your Movement at twice the regular rate.

If you have a Climb Speed, you can move at a regular pace and deduct your movement at the regular rate until you have climbed as far as your Climb Speed allows. Once your Climb Speed is expended, you use the regular rules for Climbing, seen above.

Most creatures cannot move up sheer walls or smooth, vertical surfaces unless they have a Climb Speed, although most creatures could use climbing to get over an obstacle, such as a shoulder height wall, or pulling themselves up over a ledge they are hanging from.