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State of the Poles – Mid-September 2012: Record Low Arctic Ice Extent; Antarctic Ice Above Climatological Normal

Northern Hemispheric Ice Concentration Sep 17, 2012

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.

Arctic Ice

According to the NSIDC, weather conditions only somewhat aided rapid melting across the Arctic – a continuation of similar events in the past six years. In contrast to 2007, weather conditions played a smaller role in this year’s stunning ice melt. The extent started decreasing rapidly in August and continued through early September. Indeed, the extent set daily record lows since early August, as one of the graphs below will show. Arctic sea ice extent on in June averaged 4.72 million sq. km. Every sea except for the Greenland Sea set all-time lows during this melt season. Overall, near surface temperatures were warmer than average (by 2-5F at the 925hPa level) across the Arctic Ocean.

In terms of longer, climatological trends, Arctic sea ice extent in August has decreased by 10.2% per decade. This rate is lowest in the spring months and highest in late summer/early fall months. Note that this rate also uses 1979-2000 as the climatological normal. In contrast to other months, this rate could be more negative in upcoming years, although the magnitude may not change drastically (10% is already a very large change!). Additional low ice seasons will continue to occur. Some years will see less decline than other years (like 2011) – but the multi-decadal trend is clear: very strongly 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 are actively establishing a new 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. [cont’d.]

CommunityMy FDL

State of the Poles – Mid-September 2012: Record Low Arctic Ice Extent; Antarctic Ice Above Climatological Normal

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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