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State of Polar Sea Ice – January 2013: Arctic Below and Antarctic Above Normal

8:25 am in Uncategorized by WeatherDem

Global polar sea ice area in early January 2013 remains below climatological normal conditions (1979-2009), but has improved in the past month.  Antarctic sea ice loss is occurring at a climatological normal rate.  Arctic sea ice gain is slightly more rapid than normal, but we should expect this given the record low extent that occurred in September 2012.  Polar sea ice recovered from an extensive deficit of -2.5 million sq. km. area late last year to a -500,000 sq. km. anomaly within the last week.

In March-April 2012, global sea ice area was above normal, but sea ice area anomaly quickly turned negative and then spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era in 2012.  Generally poor environmental conditions (warm surface temperatures and certain wind patterns) established and maintained this condition, predominantly across the Arctic last year.  For the third time in modern history, the minimum global sea ice area fell below 17.5 million sq. km. and for the fourth time in modern history, the anomalous global sea ice area fell below -2 million sq. km.  This is a significant development given that Antarctic sea ice area has been slightly above average during the past few years.  This means that the global anomaly is almost entirely due to worsening Arctic ice conditions.

The rapid ice melt and record-setting area and extent values that occurred in 2012 are the top weather/climate story for 2012, in my opinion.  I think we have clearly seen a switch to new conditions in the Arctic.  Whether these events will occur in similar magnitude or are merely transitory as the Arctic continues to move to a new stable state that the climate will not achieve for years or decades remains to be seen.  The problem is we don’t know all of the ramifications of moving toward or achieving that new state.  Additionally, I don’t think we want to know.

Arctic Ice

According to the NSIDC, weather conditions once again caused less freezing to occur on the Atlantic side of the Arctic Ocean and more freezing on the Pacific side.  Similar conditions occurred during the past six years.  Sea ice creation during December measured 2.33 million sq. km.  Despite this rather rapid growth, December′s extent remained far below average for the month.  Instead of measuring near 13.36 million sq. km., December 2012′s extent was only 12.2 million sq. km., a 1.16 million sq. km. difference!  The Barents and Kara Seas remained ice-free, which is a very unusual condition for them in December.  Recent ice growth in the Seas has slightly alleviated this state, but this is happening very late in the season.  The Bering Sea, which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012.  This has caused anomalously high ice extent in the Bering Sea.  Temperatures over the Barents and Kara Seas were 5-9°F above average while temperatures over Alaska were 4-13°F below average.  The reason for this is another negative phase of the Arctic Oscillation, which allows cold Arctic air to move southward.  This allows warm sub-arctic air to move north.

In terms of longer, climatological trends, Arctic sea ice extent in December has decreased by 3.5% per decade.  This rate is closest to zero in the spring months and furthest from zero in late summer/early fall months.  Note that this rate also uses 1979-2000 as the climatological normal.  There is no reason to expect this rate to change significantly (more or less negative) any time soon, but increasingly negative rates are likely in the foreseeable future.  Additional low ice seasons will continue.  Some years will see less decline than other years (like this past year) – but the multi-decadal trend is clear: negative.  The specific value for any given month during any given year is, of course, influenced by local and temporary weather conditions.  But it has become clearer every year that humans have established a new climatological normal in the Arctic with respect to sea ice.  This new normal will continue to have far-reaching implications on the weather in the mid-latitudes, where most people live.

Arctic Pictures and Graphs

The following graphic is a satellite representation of Arctic ice as of September 17, 2012 (yes, it’s been that long since I’ve written a Polar post):

Photobucket

Figure 1UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120917.

Here is the similar image from January 9, 2013:
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State of the Poles – Mid-September 2012: Record Low Arctic Ice Extent; Antarctic Ice Above Climatological Normal

7:29 am in Uncategorized by WeatherDem

Judging by recent search terms used to get to this blog and the relative recent peak in traffic, readers have been searching for this post.  I wanted to wait a little longer into the month so that I could capture the expected Arctic minimum, which officially occurred on the 16th of September.  The NSIDC announced this date, after which I started gathering the plots that are found below.  This post will be longer than it usually is because this year’s minimum shattered the record minimum set in 2007, which shattered the previous record set in 2005.  Most of the post is made up of figures, so I encourage readers to at least view them to get a good picture of today’s conditions.  I’m purposefully framing things this way to relay the truly stunning situation the Arctic is in today.  2012 is additional proof the Arctic cryosphere is searching for a new stable point, but hasn’t found it yet.  That does not bode well for the rest of the globe.  With that, let’s begin.

The state of global polar sea ice area in mid-September 2012 remains significantly below climatological normal conditions (1979-2009).  Arctic sea ice loss is solely responsible for this condition.  In fact, if Antarctic sea ice were closer to its normal value, the global area would be much lower than it is today.  Arctic sea ice melted quickly in August and the first half of September because it was thinner than usual and winds helped push ice out of the Arctic where it could melt at lower latitudes; Antarctic sea ice has refrozen at a faster than normal rate during the austral winter.  Polar sea ice recovered from an extensive deficit of -2 million sq. km. area late last year to a +750,000 sq. km. anomaly in March 2012 before falling back to a -2.2 million sq. km. deficit earlier this month.

After starting the year at a deficit from normal conditions, sea ice area spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era in 2011 (i.e., almost the entire calendar year).  Generally poor environmental conditions (warm surface temperatures and certain wind patterns) established and maintained this condition, predominantly across the Arctic last year.  The last time global sea ice area remained near 19 million sq. km. during May was in 2007, when the Arctic extent hit its modern day record minimum.  The maximum in the boreal spring the past two years was ~19.5 million sq. km.

Conditions were prime for another modern-day record sea ice extent minimum to occur in September.  Specific weather conditions helped to determine how 2012′s extent minimum ranks compared to the last 33 years, but it was the overall poor condition of Arctic sea ice that contributed to this year’s record low values.

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