In the past few years proposals have been floated to protect the NYC area from flodding by putting large gates into New York Bay. The gates would lie in the seafloor most of the time but would be raised into place during a major storm, such as Sandy. The NYTimes writes:
[Brian A. Colle] said that if gates had been placed in strategic spots like the Arthur Kill, between Staten Island and New Jersey, they would have protected some of the areas that were swamped by floodwaters, including the edges of Lower Manhattan, low-lying areas of Brooklyn and Queens and the western part of Staten Island, as well as Jersey City and Hoboken, N.J.“The idea is that you raise these barriers, and anywhere inside of that you’re basically protected,” Dr. Colle said, adding, “With a solid barrier, we basically can have business as usual in Lower Manhattan.”But vexing questions remain. Would industries tolerate immense disruption from the construction of barriers in the city’s busy waterways? Would residents object to the marring of vistas? With climate change advancing, can scientists accurately predict the size of hurricanes that the sea gates would one day have to withstand?And where would the $10 billion-plus in construction money come from? Even a study — taking into account the complexity of New York waterways, projections in the rise in sea levels and other factors — would take years and millions of dollars.The scientists and engineers who have worked on conceptual designs for the city say a comprehensive study is needed on what would be the most effective locations and the most practical type of barriers — whether they swing close like a driveway gate or pivot up from the ocean floor, for example.A feasibility study by the Army Corps of Engineers, which would have jurisdiction, would require authorization from Congress.“A lot of things need to be taken into consideration before we throw up a giant wall,” said Chris Gardner, a spokesman for the corps.
What strikes me as that time to do the preliminary study and then the actual construction is on the order of significant climate change due to global warming. Thus one can imagine that the climate is changing fast enough that such gates would be obsolete by the time they're built. These gates make sense ONLY if we take major steps to stop pumping CO2 into the atmosphere. Otherwise it's just more wishful techno-dreaming.