When companies think about risk, most of them don’t think about water. Historically, water has been available even in areas prone to drought, and flooding followed a fairly predictable pattern. But as the climate warms, the world is beginning to see more extremes — and that often means too little or too much water. Water scarcity contributes to wildfires, but other problems, too: As the water table drops, the quality of the water degrades, often leading to increasing concentrations of minerals and salts that are expensive to treat or can even make the water unusable. On the other extreme, more violent storms are already making flooding a new risk in areas that didn’t worry about it before. Floods and droughts are now sudden, unforeseen events — and increasingly hit areas in quick succession.