Record Antarctic Sea Ice In September Offsets Arctic Decline And Puzzles Scientists

Sea ice extent around Antarctica on September 22, 2013, when ice covered more of the Southern Ocean than at any other time in the satellite record. Courtesy: NASA.

Sea ice extent around Antarctica on September 22, 2013, when ice covered more of the Southern Ocean than at any other time in the satellite record. Courtesy: NASA.

Sea ice levels in the Antarctic reached a new record high last month (September 2013) forcing one expert to admit that they posed an “interesting puzzle” for scientists. Many climate scientists predict that climate change will result in a worldwide decline in sea ice levels but global sea ice levels are close to their long term average as growth in Antarctic sea ice offsets the much more widely publicised decline in the Arctic.

US space agency NASA reports that in late September 2013, the ice surrounding Antarctica reached its annual winter maximum and set a new record. Sea ice extended over 19.47m km2 (7.51 million square miles) of the Southern Ocean. The previous record of 19.44m km2 was set in September 2012.

“For the second year in a row, we set a record high winter maximum,” said Walt Meier, a glaciologist at NASA’s Goddard Space Flight Center quoted in a NASA publication. “But even though it is a record high, it is only 3.6 percent above the 1981-2010 average maximum. That means the difference between this year and an average year is that the ice edge extended an average of only about 35 kilometers (22 miles) farther this year.”

Interesting puzzle

Antarctic September sea ice has been increasing at 1.1 percent per decade relative to the 1981 to 2010 average, according to data from the National Snow & Ice Data Center of the US. “The tiny gain in Antarctica’s ice is an interesting puzzle for scientists,” said NSIDC lead scientist Ted Scambos in an NSIDC press release. “The rapid loss of ice in the Arctic should be ringing alarm bells for everyone.”

Antarctic sea ice growth contrasts with Arctic decline which is around 13 per cent per decade in September. However, the rate of change in Antarctica should be judged against the fact that it has roughly three times as much sea ice as the Arctic: some 18.8m kmversus some 6.5m km2 based on NSIDC data for the period 1981-2010.

Indeed, the Antarctic sea ice growth has offset Arctic sea ice decline and global sea ice cover has been at or near the 30-year average in 2013, according to research highlighted on the University of Illinois Department of Atmospheric Sciences Polar Research Group website based on NSIDC data (see below for chart).

The IPCC can’t explain it

There are some suggestions from computer model research and evidence from satellite tracking of ice that recent Antarctic sea ice growth may be due to wind intensification and ocean circulation changes. In simple terms, wind drives ice out to sea, creating open water near the ice-edge that is more likely to freeze. But this is far from proven as the Intergovernmental Panel on Climate Change (IPCC) implicitly acknowledged in its latest report.

This is what the IPCC said in the final draft of its AR5 science report, published last month, about the rise in Antarctic sea ice extent and the fact that it has not been reflected in climate computer models used by the IPCC:

“For Antarctic sea ice extent, the shortness of the observed record and differences in simulated and observed
variability preclude an assessment of whether or not the observed increase since 1979 is inconsistent with
internal variability. Untangling the processes involved with trends and variability in Antarctica and
surrounding waters remains complex and several studies are contradictory. In conclusion there is low
confidence in the scientific understanding of the observed increase in Antarctic sea ice extent since 1979,
due to the large differences between sea-ice simulations from CMIP5 models and to the incomplete and
competing scientific explanations for the causes of change and low confidence in estimates of internal
variability.”  This is a long-winded way of saying that they do not know what is going on here.

Troubling

Now this data should not be taken out of context by climate sceptics and used as proof that global warming is not happening but it is clear evidence that the climate is far more complicated than the IPCC – and many politicians – would like us to believe. And the fact that we can not explain it is troubling.

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Note:  publication of the September data was delayed by the US Federal Government shut-down earlier this month.

Graphs below:

Click to enlarge the pictures on this page which show: Antarctic sea ice extent in September; Arctic sea ice extent in September; the Antarctic sea ice anomaly for September versus the long term average from 1981 to 2010; the Arctic sea ice anomaly for September versus the long term trend from 1981 to 2010; Arctic sea ice extent this Summer (blue) versus the long term average (grey) and last year (dots); the total global sea ice data from the University of Illinois: the red squiggly line at the bottom is the global sea ice extent anomaly – the variation from the long term average level over the 30-year period 1979-2008 – represented by the black horizontal line running through the red line; comparison of ice seasons; and annual maximum sea ice extent in Antarctica

Antarctic sea ice extent in September 2013. Courtesy: NSIDC

Antarctic sea ice extent in September 2013. Courtesy: NSIDC

Trend in Antarctic sea ice versus long term average. Courtesy NSIDC

Trend in Antarctic sea ice versus long term average. Courtesy NSIDC

Arctic sea ice extent in September 2013. Courtesy: NSIDC

Arctic sea ice extent in September 2013. Courtesy: NSIDC

Trend in Arctic sea ice versus long term average. Courtesy: NSIDC

Trend in Arctic sea ice versus long term average. Courtesy: NSIDC

Arctic sea ice extent this Summer (blue) versus the long term average (grey) and last year (dots)

Arctic sea ice extent this Summer (blue) versus the long term average (grey) and last year (dots)

Global sea ice (red line) is close to long term average (black line through the red line) Courtesy: University of Illinois.

Global sea ice (red line) is close to long term average (black line through the red line) Courtesy: University of Illinois.

The image below shows how the 2012 and 2013 Antarctic ice growth seasons compare. In 2013 (black line) and 2012 (red line), the ice reached the highest extents ever recorded, but it was only slightly above the historical average (blue line). Light blue regions show the range of natural variability.

The image below shows how the 2012 and 2013 Antarctic ice growth seasons compare. In 2013 (black line) and 2012 (red line), the ice reached the highest extents ever recorded, but it was only slightly above the historical average (blue line). Light blue regions show the range of natural variability. Courtesy: NASA.

Maximum annual Antarctic sea ice extent in millions of square kilometres. Courtesy Nasa

Maximum annual Antarctic sea ice extent in millions of square kilometres. Courtesy Nasa

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