(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)

(THE CONVERSATION) Hurricane Harvey has taught us many lessons, but the most valuable may be the oldest lesson of all, one we humans have been learning – and forgetting – since the dawn of time: how much we all have to lose when climate and weather disasters strike.

The risks we face from disasters depend on three factors: hazard, exposure and vulnerability. In the case of Harvey, the hazard was the hurricane with its associated winds, storm surge and, most of all, rain. Houston is...