Why Is Antarctica's Sea Ice Growing While the Arctic Melts

Global warming is melting the Arctic and glaciers worldwide, but not so much the sea ice in Antarctica.

Analysis:

• Icy winds blowing off Antarctica, as well as a powerful ocean current that circles the frozen continent, are much larger factors in the formation and persistence of Antarctic sea ice than changes in temperature.
• The mighty Southern Ocean Circumpolar Current prevents warmer ocean water from reaching the Antarctic sea ice zone, helping to isolate the continent. The winds within that ice zone keep the water extremely cold, enabling the sea ice cover to grow in recent years even as global temperatures have risen markedly.
• Arctic sea ice and glaciers around the world have been dwindling quickly. This melting phenomenon is expected to lead to significant, unavoidable sea rise over centuries.
• Sea ice doesn't have a big effect on sea level—it grows and melts seasonally. The Antarctic ice shelves, by contrast, are the floating extensions of huge, land-based ice sheets and glaciers. And as they fall apart, the flow of land ice toward the sea accelerates, speeding up sea-level rise.
• Antarctic sea ice has grown somewhat over the past 10 years. Between 2012 to 2014, it reached record-high extents each year during the winter. It topped 7.78 million square miles in September 2014, the largest extent since satellites started keeping accurate measurements in 1979.
• Since the late 1970s, the Arctic has lost an average of 20,800 square miles of sea ice per year, while the Antarctic has gained an annual average of 7,300 square miles.
• As sea ice forms early in the season, wind blowing off the cold Antarctic ice cap pushes it offshore and northward. As the ice then moves away from the shore, it breaks and is pushed around by wind, eventually forming thicker ridges of ice—a sort of reef—that protects the constantly forming younger ice from being eroded by wind and waves.
• The ice at the front of the ice pack is the older ice. It's thicker and rougher...it forms a great wall that protects the ice inside, so the internal ice opens up, stretches out. In the open water, ice can grow 10 times as fast as at the front.

By: Vishal