In addition to examining the current risk, Arkema and her colleagues considered four different possibilities for the future, using current trends and predictions from the Intergovernmental Panel on Climate Change's Special Report on Emission Scenarios. Their future possibilities range from maintaining current patterns, to two "middle of the road" scenarios, to one that assumes that the Greenland ice sheet has melted, says Arkema.
If the "middle of the road" sea level rise takes place by the end of the century, the situation on the seashore will get 30 to 60 percent worse, the scientists calculated. Their model didn't include commercial property, or any increase in population or property value, so their figures – including half a trillion dollars of property damage – actually represent a massive underestimate of the probable risk from coastal hazards.
But there's hope.
Intact coral reefs, mangrove forests, and other coastal ecosystems can reduce both the likelihood and the magnitude of losses, they say. Recognizing this, the federal government passed the Coastal Barrier Resources Act (CBRA) in 1982, which ended federal subsidies for development or post-disaster rebuilding in over 3 million acres along the shore.
Right now, coastal habitats protect two thirds of the US coastline, found Arkema's team. Florida, New York, and California currently have the most people and property protected by coastal habitats, even though Alaska and North Carolina both have more coastline than either New York or California. In New York's Suffolk and Kings counties, coastal forests protect over $20 billion in residential property value.