Sport Climbers Add a New Worry (Heat) to an Old One (Gravity)

At the sport’s Olympic debut, humid conditions added an unwelcome degree of difficulty.

TOKYO — Even if there were mountains in Tokyo, reasonable climbers would not venture into such midsummer heat and humidity to climb them. Climbers tend to like cool and dry conditions, if given a choice. They hang by their fingers and often trust their body’s weight to a single point of contact — a toehold, a wedged elbow or knee, a patch of a calloused fingerprint. Gravity is the enemy of climbing. Sweat, like fatigue, fear and impatience, is a secondary one. Moisture is a lubricant that no one wants.