Protecting vital infrastructure as sea levels rise

grave consequences for the local environment. “The seepage of salt water through fracture systems would salinate aquifers for good,” says Farouk El-Baz, a geologist at Boston University who has studied the region.

Refilling the Dead Sea is no better. Because of surrounding hills, this depression could be filled to 60 meters above sea level, but even that would only offset the rise by 5 millimeters — and drown several towns into the bargain.

How about digging new holes on land to drain away a little more of the ocean? Or better still, dredging the seabed and piling the mud on nearby land to raise its level? The world’s oceans cover 360 million square kilometers, so to reverse a 1-meter rise in level, 360 trillion cubic meters of soil or sediment would have to be dug or dredged, and piled up somewhere. The scale of the task is so colossal that even nuclear explosions would not be up to it. In the Sedan nuclear test of 1962, designed to investigate the possibility of using nuclear explosions for excavating canals, mines. and so on, a 100-kilotonne bomb blew a neat hole in the Nevada desert. It is one of the largest artificial craters on Earth, but even so it would hold only a few million cubic meters of water. Even those most worried about rising sea levels would not suggest setting off hundreds of millions of such charges around the world’s coasts.

A slightly less improbable notion is to pump seawater up onto the frigid highlands of Antarctica and let it freeze. The East Antarctic ice sheet is thought to be much more stable than its shaky West Antarctic counterpart, and might hang onto its new load for thousands of years. The scale of the operation that would be required is daunting. The water would have to be pumped 1,000 kilometers or more, and raised to an altitude of at least a couple of thousand meters. The energy cost would be staggering. According to New Scientist’s calculations, to shift a meter’s worth of sea level would need several terawatts of power — in the same ballpark as the power consumption of the whole world today — sustained for a century.

“You would also have to make sure your pipes don’t freeze up, which wouldn’t be easy,” says MacCracken. He does not quite rule out the idea, pointing to the success of geothermal hot-water pipes that