Should We Try to Fight Rising Sea Levels — or Abandon the Coasts?

The world's sea levels are expected to rise 1 to 3 feet — or more — as the planet heats up in the coming century.  The more greenhouse gases we emit, the bigger the rise, but we've already locked in at least some sea-level increase no matter what.

So what should the millions of people living in low-lying coastal areas do?

Broadly speaking, there are three ways to deal with sea-level rise.  First, large coastal cities like New York or Boston or Tokyo will likely spend billions to erect dikes and other defenses to fend off the rising oceans.  Second, some coastal infrastructure will have to be elevated.

But there's a third option that rarely gets as much attention — retreat.  In many areas, it may make more sense for residents and communities to flee inland rather than fight the rising seas.

In a recent paper in Climatic Change, Carolyn Kousky argues that there are inevitably going to be parts of the United States where dikes and artificial defenses against sea-level rise probably shouldn't be built.  Often, the barriers just won't be worth the cost.  In other regions, seawalls might create more problems than they solve — by, for instance, increasing coastal erosion or by destroying crucial wetlands.

For these areas, Kousky argues, "managed retreat" is probably the best option.  But coastal communities will need to start planning ahead of time.  In some places, that may mean restricting development in high-risk areas or not subsidizing reconstruction after hurricanes and other disasters.  But there aren't any easy policy options here — and in many places, the process could get messy and controversial.

Should We Try to Fight Rising Sea Levels — or Abandon the Coasts?