Coastal floodingAn X-factor in coastal flooding: Natural climate patterns create hot spots of rapid sea level rise
Many scientists have found evidence that climate change is amplifying the impacts of hurricanes. For example, several studies just published this month conclude that human-induced climate change made rainfall during Hurricane Harvey more intense. But climate change is not the only factor making hurricanes more damaging. A recent study showed that two converging natural climate processes created a “hot spot” from Cape Hatteras, North Carolina to Miami where sea levels rose six times faster than the global average between 2011 and 2015. We also showed that such hot spots have occurred at other points along the Eastern Seaboard over the past century. Now we see indications that one is developing in Texas and Louisiana, where it likely amplified flooding during Harvey – and could make future coastal storms more damaging. Accelerations in sea level rise are hard to predict, and it is unclear whether they will become more serious over time. But they make it even more urgent for coastal communities to take sea level rise seriously today.
For Americans who live along the east and Gulf of Mexico coasts, the end of the 2017 Atlantic hurricane season on 30 November was a relief. This year forecasters recorded 17 named storms, 10 of which became hurricanes. Six were major hurricanes (Category 3 or stronger), and three made landfall: Harvey in Texas, Irma in the Caribbean and Florida, and Maria in the Caribbean and Puerto Rico. It was the costliest season ever, inflicting more than $200 billion in damages.
Many scientists have found evidence that climate change is amplifying the impacts of hurricanes. For example, several studies just published this month conclude that human-induced climate change made rainfall during Hurricane Harvey more intense. But climate change is not the only factor making hurricanes more damaging.
In a study we co-authored with our colleague Jon Martin, we showed that two converging natural climate processes created a “hot spot” from Cape Hatteras, North Carolina to Miami where sea levels rose six times faster than the global average between 2011 and 2015. We also showed that such hot spots have occurred at other points along the Eastern Seaboard over the past century. Now we see indications that one is developing in Texas and Louisiana, where it likely amplified flooding during Harvey – and could make future coastal storms more damaging.
Solving a salinity puzzle
Our work started when Jon Martin showed one of us (Arnoldo) salinity data from water trapped between sediments lining the floor of the Indian River Lagoon in east Central Florida. Here groundwater with zero salinity pools along the coast behind several barrier islands. Jon and his research team were analyzing changes in water chemistry and found that salinity had increased dramatically over the preceding decade. This suggested that saltwater was rapidly intruding into the lagoon.
