Will Melting Sea Ice Affect Coastal Cities?
Climatologists were alarmed in late July to discover nearly the entire ice sheet over Greenland showed evidence of at least some melting. Even more alarming was that the massive ice melt occurred in just four days. On July 8, the thawed area had covered 40% of the Arctic country, while days later, thawing was evidenced in 97% of the region.
Greenland normally evidences about fifty percent ice thaw during the summer months. The extent and rapidity of the ice thaw was unprecedented in terms of when NASA satellite images first began recording ice movement thirty years ago. Specialists in examining ice core records state the last time a major event such as this occurred in 1899. They state that it is not possible at this time to determine whether the melting ice sheet is a man-made phenomenon or a normal earth cycle rhythm.
Following the ice melt, which scientists say is already beginning to re-stabilize, an iceberg the size of Manhattan broke away from the Petermann Glacier in Northern Greenland. The calving was not the first major event to occur at the Petermann. In 2010, an iceberg measuring 100 square miles split from the glacier and floated out to sea. Ice calving is a normal for glaciers that terminate at the ocean. Experts say they do not affect water levels as they are already floating in the ocean, but the activity of the Petermann has raised some cause for concern.
Even more concerning is the rapid melting of the ice sheet in Antarctica. Ice melt in Western Antarctica currently accounts for close to ten percent of sea level rise. Until recently, it had not been known why the ice was melting at a far more significant rate than the rest of Antarctica, but close exploration has discovered that the area contains a geological rift as deep as the Grand Canyon. The approximately 62 mile-long Ferringo Rift is receiving warm waters from the ocean currents. As the warm waters enter the canyon, they become trapped in the interior of the Antarctic, creating more rapid ice loss.
The phenomena of warming ocean currents have not yet been fully explained. Experts suggest it is a combination of factors. A decrease in the ozone layer, which lasted for thirty years before stabilizing out, is one suggested contributor. The consequent flow of fresh water into the warmer salt water of the oceans could have created a bend in the ocean floor fresh water channels, changing the warm water currents. It is also possible that these changes have triggered a rise in thawing methane hydrates, adding warmth to the seabed.
Although Greenland has shown record ice thaw this year, scientists believe it could be a normal, periodic pattern, and that the ice sheet will solidify once more over the next eight years. There are, however, no estimates on when the ice sheet in Antarctica will re-stabilize. It is believed that even if the ice sheet continues to melt at its current rate, it would be well over a century before it had any significant effect on coastal cities.