Protecting vital infrastructure as sea levels rise

planet were put in place and worked as planned, they would have little effect on sea level over the next century unless combined with drastic emissions cuts combined with drastic emissions cuts.

In short, if coastal dwellers do not want their children and grandchildren to have to abandon land to the sea, now is the time to start coming up with Plan C. So New Scientist set out in search of the handful of researchers who have begun to think about specific ways to hold back the waters, or are at least prepared to talk about the feasibility of such ideas.

Slowing the melting of glaciers

One of the reasons why the great ice sheets of Greenland and Antarctica are already shrinking is that the ice is draining off the land faster. Ice floating on the surrounding seas usually acts as a brake, holding back glaciers on land, so as this ice is lost, the glaciers flow faster. The acceleration of the Jakobshavn glacier in Greenland is thought to be the result of warm currents melting the floating tongue of the glacier. Other outlet glaciers are being attacked in a similar way.

Mike MacCracken of the Climate Institute in Washington, D.C. is one of those starting to think that we should not just sit back and let warm currents melt ice shelves. “Is there some way of doing something to stop that flow, or cool the water?” he asks.

Last year, physicist Russel Seitz at Harvard University suggested that the planet could be cooled by using fleets of customized boats to generate swarms of tiny bubbles. This would whiten the surface of the oceans and so reflect more sunlight. MacCracken says the bubbles might be better deployed in a more focused way, to cool the currents that are undermining the Jakobshavn glacier and others like it. A couple of degrees of chill would take this water down to freezing point, rendering it harmless. “At least that would slow the pace of change,” MacCracken says.

What about a more direct approach: building a physical barrier to halt a glacier’s flow into the sea by brute force? Bindshadler thinks that is a non-starter. “The ice discharge has many sources, mostly remote and in environments where barriers are not likely to work,” he says. “Taking just the one example I know best, the Pine Island glacier in Antarctica drains into an ice shelf that at its