Humans cause growth in Antarctic sea ice

CAMBRIDGE, UK – So it’s not all bad: it seems human activity is as much to blame for the increase in Antarctic ice as it is for the melting of the Arctic ice cap. Unfortunately, the effect won’t last.

The growth in Antarctic sea ice over the last 30 years is a result of changing weather patterns caused by the ozone hole, according to scientists from the British Antarctic Survey (BAS) and NASA. They say that while there has been a dramatic loss of Arctic sea ice, Antarctic sea ice has increased by a small amount as a result of the ozone hole, delaying the impact of greenhouse gas increases on the climate of the continent.

The new research helps explain why observed changes in the amount of sea-ice cover are so different in both polar regions.

Lead author Professor John Turner of BAS said, “Our results show the complexity of climate change across the Earth. While there is increasing evidence that the loss of sea ice in the Arctic has occurred due to human activity, in the Antarctic human influence through the ozone hole has had the reverse effect and resulted in more ice.”

But, he warns, the effect is likely to be temporary. “Although the ozone hole is in many ways holding back the effects of greenhouse gas increases on the Antarctic, this will not last, as we expect ozone levels to recover by the end of the 21st century. By then there is likely to be around one third less Antarctic sea ice,” he said.

Using satellite images of sea ice and computer models the scientists discovered that the ozone hole has strengthened surface winds around Antarctica and deepened the storms in the South Pacific area of the Southern Ocean that surrounds the continent. This resulted in greater flow of cold air over the Ross Sea, leading to more ice production in this region.

Whilst there has been a small increase of sea ice during the autumn around the coast of East Antarctica, the largest changes are observed in West Antarctica. Sea ice has been lost to the west of the Antarctic Peninsula – a region that has warmed by almost 3 degrees Celcius in the past 50 years. Further west, sea ice cover over the Ross Sea has increased.

The research will be published in Geophysical Research Letters this week.