Predicting sea level rise involves many unknowns

Today’s Image of the Day from NASA Earth Observatory shows the Afsluitdijk, a 20-mile dam that separates the Wadden Sea from the freshwater Lake Ijssel in the Netherlands. 

According to NASA, without Afsluitdijk and the rest of the dams and dykes of the Zuiderzee Works, an inland sea would flood large patches of land around Lake Ijssel. To cope with sea level rise, the Dutch are currently making extensive upgrades to Afsluitdijk.

Sea level rise will impact nearly every coastline on the planet, but it will impact some places – including river deltas and island atolls – more than others. 

“One of the reasons it is difficult to offer definitive assessments about how much sea levels will lead to impacts in certain areas is that governments could respond and influence which areas will flood and which will not by building infrastructure,” said Ben Hamlington of the Jet Propulsion Laboratory and current leader of NASA’s sea level team. 

“In places like The Netherlands or the Sacramento-San Joaquin Delta, countering strategies have either already been implemented. Or it’s a good bet that dykes and other infrastructure will be built to prevent inland seas from forming where they otherwise might.”

“If you add in the isostatic rebound in formerly glaciated parts of Europe and North America, the issue becomes even more complex,” said paleoclimatologist Anders Carlson of the Oregon Glaciers Institute. 

“Throw in competing gravitational effects from the Greenland Ice Sheet, and you can start to see how we’re dealing with ‘known unknowns’ when we’re making regional sea level rise projections.”

Image Credit: NASA Earth Observatory 

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By Chrissy Sexton, Earth.com Staff Writer