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Original Source: The National Snow and Ice Data Center (NSIDC) – Questions about Arctic sea ice

Sea Ice Ebbs and Flows – NASA Earth Observatory, April 21, 2009

Why don’t I hear much about Antarctic sea ice?

NSIDC scientists do monitor sea ice in the Antarctic, and sea ice in the Antarctic is of interest to scientists worldwide. While many have published peer-reviewed journal articles on the topic, it has received less attention than the Arctic. There are several reasons for this.

Unlike Arctic sea ice, Antarctic sea ice disappears almost completely during the summer, and has since scientists have studied it. Earth’s climate system over thousands of years has been “in tune” with this annual summertime disappearance of Antarctic sea ice. However, satellite records and pre-satellite records indicate that the Arctic has not been free of summertime sea ice for at least 5,500 years and possibly for 125,000 years. So Earth’s climate system and ecosystems, as they exist today, did not develop in conjunction with an ice-free Arctic. Such an ice-free Arctic summer environment would be a change unprecedented in modern human history and could have ramifications for climate around the world.

In March 2008, Antarctica experienced a record maximum. For more information, read Is wintertime Antarctic sea ice increasing or decreasing? (below)

Antarctic sea ice data is available on the NSIDC Sea Ice Index.

Is wintertime Antarctic sea ice increasing or decreasing?

Wintertime Antarctic sea ice is increasing at a small rate and with substantial natural year-to-year variability in the time series. While Antarctic sea ice reached a near-record-high annual minimum in March 2008, this does not indicate a significant long-term trend. To borrow an analogy from sports, one high day, month, or even year of sea ice is no more significant than one early-season win would be in predicting whether the hometown team will win the Super Bowl ten seasons from now.

Another important point is that the increase in Antarctic sea ice extent is not surprising to climate scientists. When scientists refer to global warming, they don’t mean warming will occur everywhere on the planet at the same rate. In some places, temporary cooling may even occur. Antarctica is an example of regional cooling. Even our earliest climate models projected that Antarctica would be much slower in responding to rising greenhouse gas concentrations than the Arctic. In large part, this reflects the nature of the ocean structure in Antarctica, in which water warmed at the surface quickly mixes downward, making it harder to melt ice.

In terms of sea ice, climate model projections of Antarctic sea ice extent are in reasonable agreement with the observations to date. It also appears that atmospheric greenhouse gases, as well as the loss of ozone, have acted to increase the winds around Antarctica. Perhaps counter intuitively, this has further protected the Antarctic from warming and has fostered more ice growth.

The one region of Antarctica that is strongly warming is the Antarctic Peninsula, which juts out into the Atlantic Ocean and is thus less protected by the altered wind pattern. The Antarctic Peninsula is experiencing ice shelf collapse and strongly reduced sea ice.

Finally, even if wintertime Antarctic sea ice were to increase or decrease significantly in the future, it would not have a huge impact on the climate system. This is because during the Antarctic winter energy from the sun is at its weakest point; its ability or inability to reflect the sun’s energy back into space has little affect on regulating the planet’s temperature.

For more information, see All About Sea Ice: Arctic vs. Antarctic and the State of the Cryosphere: Sea Ice. To see data on Antarctic sea ice, see the Sea Ice Index.

December 1, 2009 – British Antarctic Survey


10% increase in sea ice around the Antarctic

Since 1980 there has been a 10% increase in Antarctic sea ice extent, particularly in the Ross Sea region, as a result of the stronger winds around the continent (due to the ozone hole). In contrast, regional sea ice has decreased west of the Antarctic Peninsula due to changes in local atmospheric circulation and this has also been linked with the very rapid warming seen over land on the west coast of the Peninsula.

June 30, 2005 – ScienceDaily

Predicted increases in precipitation due to warmer air temperatures from greenhouse gas emissions may actually increase sea ice volume in the Antarctic’s Southern Ocean. This finding from a new study adds evidence of potential asymmetry between the two poles and may be an indication that climate change processes may have varying impacts on different areas of the globe.


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