By Janice Kaspersen

Late last year, Canadian scientists announced that a large chunk of ice had broken free from an island near the North Pole. A researcher with the Canadian Ice Service, examining months-old satellite imagery, noticed first a 9-mile crack in the ice and, in slightly later images, the Ayles Ice Shelf floating half a mile from Ellesmere Island. The shelf ultimately traveled about 30 miles before freezing into the sea ice.

Scientists researching climate change say this event is a result of accelerated warming. It’s rare to see one break away so dramatically, but ice shelves in the Arctic have decreased through melting by as much as 90% over the last century.

Many in the ESC field might look at this event and see it as one more form of erosion. The mechanisms are different, the substance that’s being lost is different, but the change—something that usually happens gradually but sometimes, as with a landslide, on a spectacularly large scale—is uncomfortably familiar.

Articles in Erosion Control and elsewhere have long examined the effects of the loss of coastal wetlands, particularly after Hurricane Katrina. Louisiana is losing about 40 square miles of coastal marshes and wetlands each year—that’s an area about a third larger than Manhattan and, coincidentally, just about the size of the wayward Ayles Ice Shelf. We’ve known for years that the process is occurring, and we know more or less why: Navigation channels and levees built over hundreds of years to encourage commerce and protect settlements have prevented the Mississippi River from depositing silt, the process that built up the wetlands in the first place.

Their disappearance has a cascade effect: It’s been estimated that for every acre of coastal wetlands lost, the storm surge during a major hurricane increases by about a foot. The estimates vary, and it might have seemed like an academic point until August 2005, when the size of the storm surge and the exact amount of water headed for shore became a matter of urgent concern for thousands of people along the Gulf Coast.

Similarly, we know that ice shelves in the Arctic region are getting smaller, and we think we now know more or less why. What might the cascade effect be in this case? For the short term, there’s concern that the Ayles Shelf could drift farther and block shipping lanes. Over the long term, melting ice could cause gradual rises in sea level and increases in coastal erosion and flooding. The Greenland ice sheet, for example, covers more than 80% of that island’s surface and, if it melted completely, would cause sea levels to rise more than 22 feet. That’s not likely to happen soon, but according to measurements from NASA satellites, more than 57 cubic miles of it are melting away each year.

In Louisiana and other US coastal areas, projects are under way to study the erosion problem and find solutions—or, perhaps more accurately, workarounds. The canals and levees aren’t going away, but we can mitigate, to some extent, their effects on the wetlands.

No one, in the ESC field or out of it, is likely to single-handedly stop the Arctic ice from melting, but we do know something about mitigating the consequences of rising water levels and the resulting coastal erosion. This is sure to be an increasing concern for everyone in the field in the coming years; whether you live near the coast or far inland, the economics of the situation alone will have an effect, and our field’s specialized knowledge can make a big difference in what the outcomes will be. It’s time to start planning the workarounds.

Send Janice an Email

EC - March/April 2007