Beware of stupid people who are motivated and energetic.

Four hundred top-decision makers listed the myriad looming threats to global security, including famine, terrorism, inequality, disease, poverty and climate change. Yet when we tried to address each diverse force, we found them all attached to one universal security risk: fresh water.

Water is an astonishingly complex and subtle force in an economy. It is the single constraint on the expansion of every city, and bankers and corporate executives have cited it as the only natural limit to economic growth.

In today's world, only one person in every 200 is Canadian.