As a succession of crises break out on three continents, extreme weather events have added a new challenge to the world economy. By disrupting the tightly woven supply chain that is the backbone of world commerce — witness the flooded manufacturing plants in Thailand choking off supply of hard disks to the world — natural disasters have caused heavy losses to global corporations. Over the medium term, austerity measures and painful reforms could help economic recovery, but extreme weather conditions seem destined to become the new normal.