The most cost-effective approach would be to invest $75 billion into building flood walls around some of these communities. Kunreuther and Michel-Kerjan calculate the benefits over the next 50 years as $4.5 trillion, making the benefits a remarkable 60 times higher than the costs. Those benefits would mostly come from reduction in damages, though the walls would also save 20,000 lives.
Efficient means of combating flood damages
