Rising seas are rising faster than recently thought. Scientists now point to Greenland and Antarctic ice sheets melting much faster than previously reported as the cause.Â Seas are now predicted to have risen at least six inches by 2050, due to ice melt alone in these two ice sheets, and as much as 22 inches by the turn of the century.
The really bad news isÂ… the total sea level rise by 2050 will be more like twelve inches, and by the turn of the century, as much as triple thatÂ… or more.Â Mountain glacier melt and seawater expansion caused by climate change (global warming) will account about equally for the additional rise in the near term, but mountain glacier contributions should be minimal well before the turn of the century.Â Sea warming, however, will continue.
The rate of melt at the poles has increased rapidly in the past few years, according to NASA data, and shows no sign of slowing.Â This nearly 20 year study included two very different and independent modes of investigation: Â“Â…the mass budget method and time-variable gravity measurements from the NASA/German Aerospace CenterÂ’s Gravity Recovery and Climate Experiment (Grace) satellites.
Rising seas pose their greatest threat in coastal areas and low-lying land, of course.Â As much as 25 Â– 30% of southern Florida could be under sea water.Â But the threat is not simply in flooding due to higher water, it is also due to the greater storm surges that will occur at the land-ocean interface.Â Cities and homes that might survive higher seas by diking and seawalls will be inundated by storm surges and the greater number and intensity of hurricanes brought by the higher and warmer seas.
This new empirical data indicates strongly that rising seas are increasing much faster than projected by the Intergovernmental Panel on Climate Change (IPCC) in its landmark 2007 assessment.Â The IPCC models do not seem to be accounting for nearly enough melt in these two ice sheets in the near term.Â The result is that within two decades or less, much of low-lying coastal America will be under constant attack by seas that have risen six inches on average.Â However, because warming occurs more at the equator, southern American coastal areas will be under greater threat from rising seas than more northern areas.
This is going to become astoundingly expensive, and soon.