THE WORLD Bank has warned countries that one of climate change’s most significant impacts will be on a precious resource that many people, particularly in advanced nations, take for granted: water. The concerns go far beyond sea-level rise, which is perhaps the most predictable result of the planet’s increasing temperature, or an uptick in extreme weather. Countries must worry about whether their people will have enough fresh water to farm, produce electricity, bathe and drink.

Global warming will not change the amount of water in the world, but it will affect water’s distribution across countries, making some much worse off.