Rising Seas

One of the lovely sights in Greece is the view at Sounion of the ruins of the temple of Poseidon rising from the sea. Treasured by ancient sailors as the first sight of home by travelers returning from a voyage, it draws thousands today as a spot not only lovely in itself, but a place where moonrise and sunset can be seen together.  It has been so popular so long that graffiti on its walls includes the signature of Lord Byron alongside that of Romans and Greeks.  Soon it may be rivaled as a tourist draw by the sight of the Statue of Liberty sinking into the sea.  That is the view of it depicted on the cover of the September National Geographic magazine, where the feature article is about the coastal cities of the world endangered by rising sea levels.  For of the five most endangered cities in the world, two are in the U.S., Miami as number one and New York close behind at number three.

New York and the Statue are so endangered because the shape of New York harbor, along with steadily rising seas, means that a storm like Sandy in 2100 will flood the entire financial district and large portions of the rest of the city.  That of course has national implications as well.  About three trillion dollars is the current estimate of potential damage.  Miami is in far worse danger.   The Florida peninsula is composed mostly of porous limestone, so not only will rising seas flood most of southern Florida, leaving Miami at best as an island, but the seawater will long before drive out fresh ground water from the peninsula, leaving nothing for drinking or cultivating crops.  And of course, those who own the land will find it impossible to sell.  One Florida hydrologist is quoted as saying he’s looking for a rich climate change denier with lots of cash to whom he can sell his land.

The reason hydrologists are so pessimistic is that they now regard it as a foregone conclusion that sea levels will rise at least five feet by 2100.  That’s the cautious prediction of the Army Engineers, while the U.N. science groups studying the issue already have it pegged at six feet and are expected to raise that to seven feet in a report to be issued this Fall. The closeness of their calculations shows the scientific theory is rapidly turning into hard fact.   It will take only a two foot rise for seawater to begin to drive fresh water out of Florida. The big unknown in the equations is the state of the western Antarctic glaciers – miles of ice two thousand feet deep poised precariously atop a slope to the sea, held only by their ice’s anchoring to the rock.  If rising sea levels cause sea water to penetrate the bottom of the glaciers, loosening their anchor, then all bets are off.  The slippage of the glaciers into the sea could raise sea levels another ten feet.  In any event, New York City is on course to be the Venice of the 22^nd century.

The tough news is that scientists are already turning from shouting climate change into deaf ears to begin figuring out how best to ameliorate its impacts.  We will face enormous impacts from droughts due to evaporation of moisture from the soil, severe weather – Sandy is just among our first, most dramatic examples – and from rising temperatures some places and increasing cold elsewhere as atmospheric patterns and ocean currents shift about.  But the most visible effects early on include the dangers to coastal areas around the world. Those dangers will require construction of enormous infrastructures.  Ask the Dutch – they’ve been there.  A tremendous amount of effort and money must be spent in the coming years to do that construction, and defining the best approach is not an easy issue.  No one choice fits everywhere.  Some places like New York City face their most immediate danger from rising levels of storm surge, while other places like Miami face the slow, inexorable rise of the sea itself.  In a port city, sea gates that block surges do no good against the inch-by-inch rise of the sea.  That requires dikes and levees which, unless wisely planned, could block the ship traffic on which the port relies.  That is part of the decision making that New York City is just beginning to tackle now with Mayor Bloomberg’s proposals.

Meanwhile, no one in the Congress seems willing to talk about infrastructure spending by government or about climate change at all.  That local businessman the Republicans worry so much about is not going to be able to afford his own seawall.  In another twenty years, the Army Engineers may become the largest agency of all, outranking Homeland Security.  Decisions must be made.  Like Canute, we cannot tell the tide not to rise.