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State of Polar Sea Ice – March 2014: Arctic Sea Ice Maximum and Antarctic Sea Minimum

Global polar sea ice area in March 2014 remained at or near climatological normal conditions (1979-2008).  This represents early 2013 conditions continuing to present when sea ice area was at or above the average daily value.  Global sea ice area values consist of two components: Arctic and Antarctic sea ice.  Conditions are quite different between these two regions: Antarctic sea ice continues to exist abundantly while Arctic sea ice remained well below normal again during the past five months.

The NSIDC made a very important change to its dataset in June.  With more than 30 years’ worth of satellite-era data, they recalculated climatological normals to agree with World Meteorological Organization standards.  The new climatological era runs from 1981-2010 (see Figure 6 below).  What impacts did this have on their data?  The means and standard deviations now encompass the time period of fastest Arctic melt.  As a consequence, the 1981-2010 values are much lower than the 1979-2000 values.  This is often one of the most challenging conditions to explain to the public.  “Normal”, scientifically defined, is often different from “normal” as most people refer to it.  U.S. temperature anomalies reported in the past couple of years refer to a similar 1981-2010 “normal period”.  Those anomalies are smaller in value than if we compared them to the previous 1971-2000 “normal period”.  Thus, temperature anomalies don’t seem to increase as much as they would if scientists referred to the same reference period.

Arctic Sea Ice

According to the NSIDC, March 2014′s average extent was 14.80 million sq. km., a 730,000 sq. km. difference from normal conditions.  This value is the maximum for 2014 as more sunlight and warmer spring temperatures now allow for melting ice.  March 2014 sea ice extent continued a nearly two-year long trend of below normal values.  The deficit from normal was different each month during that time due to weather conditions overlaying longer term climate signals.  Arctic sea ice extent could increase during the next month or so depending on specific wind conditions, but as I wrote above, we likely witnessed 2014’s maximum Arctic sea ice extent 10 or so days ago.

Sea ice anomalies at the edge of the pack are of interest.  There is slightly more ice than normal in the St. Lawrence and Newfounland Seas on the Atlantic side of the pack.  Barents sea ice area, meanwhile, is slightly below normal.  Bering Sea ice recently returned to normal from below normal, while Sea of Okhotsk sea ice remains below normal.  The ice in these seas will melt first since they are on the edge of the ice pack and are the thinnest since they just formed in the last month.

March average sea ice extent for 2014 was the fifth lowest in the satellite record.  The March linear rate of decline is 2.6% per decade relative to the 1981 to 2012 average, as Figure 1 shows (compared to 13.7% per decade decline for September: summer ice is more affected from climate change than winter ice).  Figure 1 also shows that March 2014′s mean extent ranked fifth lowest on record.

 photo Arctic_monthly_sea_ice_extent_201403_zpsf13de46a.png

Figure 1 – Mean Sea Ice Extent for March: 1979-2014 [NSIDC].

Arctic Pictures and Graphs

The following graphic is a satellite representation of Arctic ice as of October 1st, 2013:

 photo Arctic_sea_ice_20131001_zps56b337ee.png

Figure 2UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20131001.

The following graphic is a satellite representation of Arctic ice as of January 15th, 2014:

 photo Arctic_sea_ice_20140115_zps96036b51.png

Figure 3UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20140115.

The following graphic is a satellite representation of Arctic ice as of April 1st, 2014:

 photo Arctic_sea_ice_20140401_zpsdd9dbc04.png

Figure 4 UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20140401.

I captured Figure 2 right after 2013’s date of minimum ice extent occurrence.  I wasn’t able to put together a post in January on polar sea ice, but captured Figure 3 for future reference.  You can see the rapid growth of ice area and extent in three month’s time.  Since January, additional sea ice formed, but not nearly as much as during the previous three months.  Figure 4 shows conditions just after the annual maximum sea ice area occurred.  From this point through late September, the overall trend will be melting ice – from the edge inward.

The following graph of Arctic ice volume from the end of January (PIOMAS updates are not available from the end of February or March) demonstrates the relative decline in ice health with time:

 photo SeaIceVolumeAnomaly_20140131_zpse02b6133.png

Figure 5PIOMAS Arctic sea ice volume time series through January 2014.

The blue line is the linear trend, identified as -3,000 km^3 (+/- 1,000 km^3) per decade.  In 1980, there was a +5,000 km^3 anomaly compared to 2013’s -6,000 km^3 anomaly – a difference of 11,000 km^3.  How much ice is that?  That volume of ice is equivalent to the volume in Lake Superior!

Arctic Sea Ice Extent

Take a look at March’s areal extent time series data:

 photo N_stddev_timeseries_20140401_1_zps069b9c1d.png

Figure 6NSIDC Arctic sea ice extent time series through early April 2014 (light blue line) compared with four recent years’ data, climatological norm (dark gray line) and +/-2 standard deviation envelope (light gray).

This figure puts winter 2013-14 into context against other recent winters.  As you can see, Arctic sea ice extent was at or below the bottom of the negative 2nd standard deviation from the 1981-2012 mean.  The 2nd standard deviation envelope covers 95% of all observations.  That means the past five winters were extremely low compared to climatology.  With the maximum ice extent in mid-March, 2014’s extent now hovers near record lows for the date.  Previous winters saw a late-season ice formation surge caused by specific weather patterns.  Those patterns are not likely to increase sea ice extent this boreal spring.  This doesn’t mean much at all for projections of minimum sea ice extent values, as the NSIDC discusses in this month’s report.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from October 1, 2013:

 photo Antarctic_sea_ice_20131001_zps2fb64db9.png

Figure 7UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20131001.

And here is the corresponding graphic from January 15th, 2014:

 photo Antarctic_sea_ice_20140115_zpsd2a383a2.png

Figure 8UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20140115.

The following graphic is a satellite representation of Antarctic ice as of April 2nd, 2014:

 photo Antarctic_sea_ice_20140401_zpsd15f0ddf.png

Figure 9UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20140402.

Antarctic sea ice clearly hit its minimum between mid-January and early April.  In fact, that date was likely six weeks ago.  Antarctic sea ice is forming again as austral fall is underway.  As in recent austral summers, the lack of sea ice around some locations in Figure 8 is related to melting land-based ice.  Likewise,  sea ice presence around other locations is a good indication that there is less land-based ice melt.  Figure 8 looks different from other January’s prior to 2012 and 2013.  Additionally, Antarctic weather in recent summers differed from previous years in that winds blew land-based ice onto the sea, especially east of the Antarctic Peninsula (jutting up towards South America), which replenished the sea ice that did melt.  The net effect of the these and other processes kept Antarctic sea ice at or above the 1979-2008 climatology’s positive 2nd standard deviation, as Figure 10 below shows.

Finally, here is the Antarctic sea ice extent time series through early April:

 photo S_stddev_timeseries_20140401_zpscadac617.png

Figure 10NSIDC Antarctic sea ice extent time series through early April 2014.

The fact that Arctic ice extent continues well below average while Antarctic ice extent continues well above average for the past couple of years works against climate activists who claim climate change is nothing but disaster and catastrophe.  A reasonable person without polar expertise likely looks at Figures 6 and 10 and says, “I don’t see evidence of catastrophe here.   I see something bad in one place and something good in another place.”  For people without the time or inclination to invest in the layered nuances of climate, most activists come off sounding out of touch.  If climate change really were as clearly devastating as activists screamed it was, wouldn’t it be obvious in all these pictures and plots?  Or, as I’ve commented at other places recently, do you really think people who are insecure about their jobs and savings even have the time for this kind of information?  I don’t have one family member or friend that regularly questions me about the state of the climate, despite knowing that’s what I research and keep tabs on.  Well actually, I do have one family member, but he is also a researcher and works in supercomputing.  Neither he nor I are what most people would consider “average Joes” on this topic.

Policy

Given the lack of climate policy development at a national or international level to date, Arctic conditions will likely continue to deteriorate for the foreseeable future.  This is especially true when you consider that climate effects today are largely due to greenhouse gas concentrations from 30 years ago.  It takes a long time for the additional radiative forcing to make its way through the entire climate system.  The Arctic Ocean will soak up additional energy (heat) from the Sun due to lack of reflective sea ice each summer.  Additional energy in the climate system creates cascading and nonlinear effects throughout the system.  For instance, excess energy pushes the Arctic Oscillation to a more negative phase, which allows anomalously cold air to pour south over Northern Hemisphere land masses while warm air moves over the Arctic during the winter.  This in turn impacts weather patterns throughout the year (witness winter 2013-14 weather stories) across the mid-latitudes and prevents rapid ice growth where we want it.

More worrisome for the long-term is the heat that impacts land-based ice.  As glaciers and ice sheets melt, sea-level rise occurs.  Beyond the increasing rate of sea-level rise due to thermal expansion (excess energy, see above), storms have more water to push onshore as they move along coastlines.  We can continue to react to these developments as we’ve mostly done so far and allocate billions of dollars in relief funds because of all the human infrastructure lining our coasts.  Or we can be proactive, minimize future global effects, and reduce societal costs.  The choice remains ours.

Errata

Here are my State of Polar Sea Ice posts from October and July 2013. For further comparison, here is my State of Polar Sea Ice post from late March 2013.


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State of Polar Sea Ice – September 2013: Arctic Sea Ice Minimum and Antarctic Sea Maximum

Global polar sea ice area in September 2013 was slightly below climatological normal conditions (1979-2008).  This represents a change from early 2013 conditions when sea ice area was at or above the average daily value.  Antarctic sea ice continues to exist abundantly while Arctic sea ice fell below normal again during the month.

The NSIDC made a very important change to its dataset in June.  With more than 30 years’ worth of satellite-era data, they recalculated climatological normals to agree with World Meteorological Organization standards.  The new climatological era runs from 1981-2010 (see Figure 6 below).  What impacts did this have on their data?  The means and standard deviations now encompass the time period of fastest Arctic melt.  As a consequence, the 1981-2010 values are much lower than the 1979-2000 values.  This is often one of the most challenging conditions to explain to the public.  “Normal”, scientifically defined, is often different than “normal” as most people refer to it.  U.S. temperature anomalies reported in the past couple of years refer to a similar 1981-2010 “normal period”.  Those anomalies are smaller in value than if we compared them to the previous 1971-2000 “normal period”.  Thus, temperature anomalies don’t seem to increase as much as they would if scientists referred to the same reference period.

Arctic Sea Ice

According to the NSIDC, September 2013′s average extent was only 5.35 million sq. km., a 1.17 million sq. km. difference from normal conditions.  This value is the minimum for 2013 as less sunlight and cooler autumn temperatures now allow for ice to refreeze.  September 2013 sea ice extent was 1.72 million square kilometers higher than the previous record low for the month that occurred in 2012.  The shift from a record low value one  year to a non-record low the next is completely normal.  Indeed, had Arctic sea ice extent fallen to a new record low, conditions this year would have been much more inhospitable to sea ice than they were.  To be clear, I do not cheer new record lows.  They are worthy of discussion not simply because of the record they set, but because they are part of a larger ongoing trend.  This year’s minimum extent value did not break that trend, it continued it.

Overall, conditions across the Arctic Ocean this summer prevented record-setting ice loss.  There were more clouds in 2013 than 2012.  Clouds reflect most incoming solar radiation, which means less sea ice melts.  At the end of the melt season, many small seas had normal sea ice extent, which is to say none.  Anomalous areas include the East Siberian Sea and the Arctic Basin, which recorded less sea ice extent than normal.

September average sea ice extent for 2013 was the sixth lowest in the satellite record. The 2012 September extent was 32% lower than this year’s extent.  The September linear rate of decline is 13.7% per decade relative to the 1981 to 2010 average, as Figure 1 shows.  Figure 1 also shows that September 2013’s mean extent ranked sixth lowest on record.  You can see from the graph that although a new record minimum was not set in 2013, the negative multi-year trend continued.

 photo Arctic_monthly_sea_ice_extent_201309_zpsf6898e0a.png

Figure 1 – Mean Sea Ice Extent for Septembers: 1979-2013 [NSIDC].

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State of Polar Sea Ice – June 2013: Arctic Sea Ice Decline and Antarctic Sea Ice Gain

Global polar sea ice area in June 2013 remained at or slightly above climatological normal conditions (1979-2008).  This follows early 2013 conditions’ improvement from September 2012′s significant negative deviation from normal conditions (from -2.5 million sq. km. to +500,000 sq. km.).  Early austral fall conditions helped create an abundance of Antarctic sea ice while colder than normal boreal spring conditions helped slow the rate of ice melt in the Arctic.

The NSIDC made a very important change to its dataset in June.  With more than 30 years’ worth of satellite-era data, they recalculated climatological normals to agree with World Meteorological Organization standards.  The new climatological era runs from 1981-2010 (see Figure 5 below).  What impacts did this have on their data?  The means and standard deviations now encompass the time period of fastest Arctic melt.  As a consequence, the 1981-2010 values are much lower than the 1979-2000 values.  This is often one of the most challenging conditions to explain to the public.  “Normal”, scientifically defined, is often different than “normal” as most people refer to it.  U.S. temperature anomalies reported in the past couple of years refer to a similar 1981-2010 “normal period”.  Those anomalies are smaller in value than if they were compared to the previous 1971-2000 “normal period”.  Thus, temperature anomalies don’t seem to increase as much as they would if scientists referred to the same reference period.

Arctic Sea Ice

According to the NSIDC, sea ice melt during June measured 2.10 million sq. km.  This melt rate was slower than normal for the month, but June′s extent remained below average – a condition the ice hasn’t hurdled since this time last year.  Instead of measuring near 11.89 million sq. km., June 2013′s average extent was only 11.5 million sq. km., a 300,000 sq. km. difference.

Barents Sea (Atlantic side) ice remained below its climatological normal value during the month, which continues the trend that began this last winter.  Kara Sea (Atlantic side) ice temporarily recovered from its wintertime low extent and reached normal conditions earlier this year, but fell back below normal during May through June.  Arctic Basin sea ice (surrounding the North Pole) fell below normal during June due to earlier weather conditions that sheared ice apart.  The Bering Sea (Pacific side), which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012 through March 2013.  Since then, Bering Sea ice extent returned to normal for this time of year: zero.  The previous negative Arctic Oscillation phase gave way to normal conditions throughout June.  However, a stronger than normal Arctic Low set up which kept Arctic weather conditions cooler and stormier than normal.  These conditions prevented Arctic sea ice from melting as quickly in June as it did in 2012.  In the past few days, these conditions eased and rapid Arctic melt is once again underway.  I’ll have more to say about this in next month’s post.

For the first time in a number of years, Arctic sea ice extent in June didn’t reach a bottom-ten status.  June Arctic sea ice extent was “only” the 11th lowest on record.  In terms of climatological trends, Arctic sea ice extent in June decreased by 3.6% per decade.  This rate is closest to zero in the late winter/early spring months and furthest from zero in late summer/early fall months.  Note that this rate also uses 1981-2010 as the climatological normal.  There is no reason to expect this rate to change significantly (much more or less negative) any time soon, but negative rates are likely to slowly become more negative for the foreseeable future.  Additional low ice seasons will continue.  Some years will see less decline than other years (e.g., 2011) – 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 June 13, 2013:

 photo Arctic_sea_ice_20130613_zpsde15c255.png

Figure 1UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130613.

The following graphic is a satellite representation of Arctic ice as of July 4, 2013:

 photo Arctic_sea_ice_20130704_zps808dd919.png

Figure 2UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130704.

Continued melt around the Arctic ice periphery is evident in the newest figure.  Hudson Bay ice is nearly gone.  Rapid melt is also evident in the Kara, Barents, and Bering Seas.  Compared to last year at the same time, more ice is present in the Baffin/Newfoundland, Beaufort, and Kara Seas.  This is due to interannual weather and sea variability.  The climate trend remains clear: widespread and rapid sea ice melt is the new normal for the Arctic.

So far, the early season thinning of sea ice near the North Pole hasn’t caused a mid-season mid-ocean collapse of sea ice, as many people feared.  This is not to say that rapid ice melt in the central Arctic Ocean will not happen this year.  We simply have to wait and see what happens before we issue obituaries.

The following graph of Arctic ice volume from the end of June demonstrates the relative decline in ice health with time:

 photo SeaIceVolumeAnomaly_20130630_zps85e7de79.png

Figure 3PIOMAS Arctic sea ice volume time series through June 2013.

As the graph shows, volume (length*width*height) hit another record minimum in June 2013.  Moreover, that volume remained far from normal for the past three years in a clear break from pre-2010 conditions.  Conditions between -1 and -2 standard deviations are somewhat rare and conditions outside the -2 standard deviation threshold (see the line below the shaded area on the graph above) are incredibly rare: the chances of 3 of them occurring in 3 subsequent years under normal conditions are extraordinarily low (you have a better chance of winning the Powerball than this).  Hence my assessment that “normal” conditions in the Arctic shifted from what they were in the past few centuries; humans are creating a new normal for the Arctic.  Note further that the ice volume anomaly returned to near the -1 standard deviation envelope in early 2011, early 2012, and now early 2013.  In each of the previous two years, volume fell rapidly outside of the -2 standard deviation area with the return of summer.  That provides further evidence that natural conditions are not the likely cause; rather, the more likely cause is human influence.

Arctic Sea Ice Extent

Take a look at May’s areal extent time series data:

 photo N_stddev_timeseries_20130704_1_zpsd03c4765.png

Figure 4NSIDC Arctic sea ice extent time series through early July 2013 compared with five recent years’ data, climatological norm (dark gray line) and standard deviation envelope (light gray).

As you can see, this year’s extent (light blue curve)  remained at historically low levels throughout the spring, well below average values (thick gray curve), just as it did in the previous five springs.  Sea ice extent did something different this spring and early summer: the late season surge of ice formation seen in the  2009, 2010, and 2012 curves was not as strong this year; the early summer surge of ice melt seen in the 2010, 2011, and 2012 curves was also not as strong this year, at least not until the last week or so.  This graph also demonstrates that late-season ice formation surges have little effect on ice extent minima recorded in September each year.  The primary reason for this is the lack of ice depth due to previous year ice melt.  I will pay close attention to this time series throughout June to see if this year’s curve follows 2012′s.  Note the sharp decrease in sea ice extent in mid-June 2012.  That helped pave the way for last year’s record low September extent, even though weather conditions were not as a factor as they were during the 2007 record low season.

 photo N_stddev_timeseries_20130704_2_zpsb4d45830.png

Figure 5 – Graph comparing two climatological normal periods: 1979-2000 (light blue solid line with dark gray shaded envelope) and 1981-2010 (purple solid line with light gray shaded envelope).  Also displayed is the Arctic sea ice extent for 2012 (green dashed line) and 2013 (light purple solid line).

This figure demonstrates the effect of adding ten years’ of low sea ice extent data in a data set’s mean and standard deviation values.  The 1981-2010 mean is lower than the 1979-2000 mean for all dates but the difference is greatest near the annual minimum extent in mid-September.  Likewise, the new standard deviation is much larger than the previous standard deviation.  This means that recent variance exceeds variance from the previous period.  This shows graphically what I’ve written about in these posts: the Arctic entered a new normal within the past 10 years.  What awaits us in the future?  For starters, scientists expect that the annual minimum extent will nearly reach zero.  The timing of that condition remains up for debate.  I think it will happen within the next ten years, rather than thirty years as others predict.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from June 13, 2013:

 photo Antarctic_sea_ice_20130613_zpsbe2cd3c3.png

Figure 6UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130613.

And here is the corresponding graphic from July 4, 2013:

 photo Antarctic_sea_ice_20130704_zps2529650e.png

Figure 7UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130704.

Sea ice growth in the past two months is within climatological norms.  However, there is more Antarctic sea ice today than there normally is on this calendar date.  The reason for this is the presence of early-season extra ice in the Weddell Sea (east of the Antarctic Peninsula that juts up toward South America).  This ice existed this past austral (Southern Hemisphere) summer due to an anomalous atmospheric circulation pattern: persistent high pressure west of the Weddell Sea.  This pressure system caused winds that pushed the sea ice north and also moved cold Antarctic air over the Sea, which kept ice melt rate well below normal.  A similar mechanism helped sea ice form in the Bering Sea last winter.  Where did the anomalous winds come from?  We can again point to a climatic relationship.

The difference between the noticeable and significant long-term Arctic ice loss and relative lack of Antarctic ice loss is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent in the 20th century.  This depletion has caused a colder southern polar stratosphere than it otherwise would be.  Why?  Because ozone heats the air around it after it absorbs UV radiation and re-radiates it to its environment.  Will less ozone, there is less stratospheric heating.  This process reinforced the polar vortex over the Antarctic Circle.  This is almost exactly the opposite dynamical condition than exists over the Arctic with the negative phase of the Arctic Oscillation.  The southern polar vortex has helped keep cold, stormy weather in place over Antarctica that might not otherwise would have occurred to the same extent and intensity. The vortex and associated anomalous high pressure centers kept ice and cold air over places such as the Weddell Sea this year.

As the “ozone hole” continues to recover during this century, the effects of global warming will become more clear in this region, especially if ocean warming continues to melt sea-based Antarctic ice from below (subs. req’d).  The strong Antarctic polar vortex will likely weaken back to a more normal state and anomalous high pressure centers that keep ice flowing into the ocean will not form as often.  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.  In the next few decades, we will have more than enough to contend with from Greenland ice sheet melt.  Were we to face a melting West Antarctic Ice Sheet at the same time, we would have to allocate many more resources.  Of course, in a few decades, we’re likely to face just such a situation.

Finally, here is the Antarctic sea ice extent time series through early July:

 photo S_stddev_timeseries_20130704_zpsc6c44a01.png

Figure 8NSIDC Antarctic sea ice extent time series through early July 2013.

The 2013 time series continues to track near the top of the +2 standard deviation envelope and above the 2012 time series.  Unlike the Arctic, there is no clear trend toward higher or lower sea ice extent conditions in the Antarctic Ocean.

Policy

Given the lack of climate policy development at a national or international level to date, Arctic conditions will likely continue to deteriorate for the foreseeable future.  This is especially true when you consider that climate effects today are largely due to greenhouse gas concentrations from 30 years ago.  It takes a long time for the additional radiative forcing to make its way through the climate system.  The Arctic Ocean will soak up additional energy (heat) from the Sun due to lack of reflective sea ice each summer.  Additional energy in the climate system creates cascading and nonlinear effects throughout the system.  For instance, excess energy pushes the Arctic Oscillation to a more negative phase, which allows anomalously cold air to pour south over Northern Hemisphere land masses while warm air moves over the Arctic during the winter.  This in turn impacts weather patterns throughout the year across the mid-latitudes and prevents rapid ice growth where we want it.

More worrisome for the long-term is the heat that impacts land-based ice.  As glaciers and ice sheets melt, sea-level rise occurs.  Beyond the increasing rate of sea-level rise due to thermal expansion (excess energy, see above), storms have more water to push onshore as they move along coastlines.  We can continue to react to these developments as we’ve mostly done so far and allocate billions of dollars in relief funds because of all the human infrastructure lining our coasts.  Or we can be proactive, minimize future global effects, and reduce societal costs.  The choice remains ours.

Errata

Here are my State of Polar Sea Ice posts from June and May 2013. For further comparison, here is my State of Polar Sea Ice post from July 2012.


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State of Polar Sea Ice – May 2013: Arctic Sea Ice Decline and Antarctic Sea Ice Gain

Global polar sea ice area in May 2013 remained at or slightly above climatological normal conditions (1979-2009).  This follows early 2013 conditions’ improvement from September 2012′s significant negative deviation from normal conditions (from -2.5 million sq. km. to +500,000 sq. km.).  While Antarctic sea ice gain was slightly more than the climatological normal rate following the austral summer, Arctic sea ice loss was slightly more than normal during the same period.

Arctic Sea Ice

According to the NSIDC, sea ice melt during May measured 1.12 million sq. km.  This melt rate was slower than normal for the month, but May′s extent remained below average – a condition the ice hasn’t hurdled since this time last year.  Instead of measuring near 13.6 million sq. km., May 2013′s average extent was only 13.1 million sq. km., a 500,000 sq. km. difference.  In terms of annual maximum values, 2013′s 15.13 million sq. km. was 733,000 lower than normal.

Barents Sea (Atlantic side) ice once again fell from its climatological normal value during the month after remaining low during most of the winter.  Kara Sea (Atlantic side) ice temporarily recovered from its wintertime low extent and reached normal conditions earlier this year, but fell back below normal during May.  The Bering Sea (Pacific side), which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012 through March 2013.  As it did previously this winter, an extended negative phase of the Arctic Oscillation allowed cold Arctic air to move far southward and brought warmer than normal air to move north over parts of the Arctic.  The AO’s tendency toward its negative phase in recent winters relates to the lack of sea ice over the Arctic Ocean in September each fall.  Warmer air slows the growth of ice, especially ice thickness.  This slow growth allows more melt than normal during the subsequent summer, which helps establish and maintain negative AO phases.  This is a destructive annual cycle for Arctic sea ice.

In terms of climatological trends, Arctic sea ice extent in May has decreased by 2.24% per decade.  This rate is closest to zero in the late winter/early 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 (much more or less negative) any time soon, but negative rates are likely to slowly become more negative for the foreseeable future.  Additional low ice seasons will continue.  Some years will see less decline than other years (e.g., 2011) – 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 May 10, 2013: photo Arctic_sea_ice_20130510_zps95770d27.png

Figure 1UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130324.

Here is the similar image from June 13, 2013:

 photo Arctic_sea_ice_20130613_zpsde15c255.png

Figure 2UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130510.

The early season melt is evident in the Sea of Okhotsk, the Bering Sea,  the Baffin/Newfoundland Bay area, the Barents Sea, and the Kara Sea.  Ice finished forming in these regions at the latest point in the winter.  As such, sea ice is the thinnest there and most susceptible to weather and solar heating.  Weather and ocean currents are also able to transport this ice around and out of the Arctic, as this animation demonstrates.  Currents will continue to transport sea ice out of the Arctic, after which the ice melts at lower latitudes.

The recent lack of sea ice thickness near the North Pole is also troubling.  This is a result of weather conditions from late May through early June that were able to easily push thin sea ice around; this has not been seen before this year.  As I mentioned in my two previous series posts, we do not yet know what effect early season anomalies such as vast ice cracks or thinning sea ice might have on end-of-season sea ice extent.  We are literally charting new history with these events, which means we have more theories than answers.

The following graph of Arctic ice volume from the end of May demonstrates the relative decline in ice health with time:

 photo SeaIceVolumeAnomaly_20130531_zps051f50ce.png

Figure 3PIOMAS Arctic sea ice volume time series through May 2013.

As the graph shows, volume (length*width*height) hit another record minimum in June 2012.  Moreover, the volume remained far from normal for the past three years in a clear break from pre-2010 conditions.  Conditions between -1 and -2 standard deviations are somewhat rare and conditions outside the -2 standard deviation threshold (see the line below the shaded area on the graph above) are incredibly rare: the chances of 3 of them occurring in 3 subsequent years under normal conditions are extraordinarily low (you have a better chance of winning the Powerball than this).  Hence my assessment that “normal” conditions in the Arctic shifted from what they were in the past few centuries; humans are creating a new normal for the Arctic.  Note further that the ice volume anomaly returned to near the -1 standard deviation envelope in early 2011, early 2012, and now early 2013.  In each of the previous two years, volume fell rapidly outside of the -2 standard deviation area with the return of summer.  That provides further evidence that natural conditions are not the likely cause; rather, the more likely cause is human influence.

Arctic Sea Ice Extent

Take a look at May’s areal extent time series data:

 photo N_stddev_timeseries_20130613_2_zpse5413c25.png

Figure 4NSIDC Arctic sea ice extent time series through early June 2013 compared with four other low years’ data, climatological norm (dark gray line) and standard deviation envelope (light gray).

As you can see, this year’s extent (light blue curve)  remained at historically low levels throughout the winter, well below average values (thick gray curve), just as it did in the previous four winters.  Sea ice extent did something different this spring: the late season surge of ice formation seen in the  2009, 2010, and 2012 curves was not as strong this year.  This graph also demonstrates that late-season ice formation surges have little effect on ice extent minima recorded in September each year.  The primary reason for this is the lack of ice depth due to previous year ice melt.  I will pay close attention to this time series throughout June to see if this year’s curve follows 2012’s.  Note the sharp decrease in sea ice extent in mid-June 2012.  That helped pave the way for last year’s record low September extent, even though weather conditions were not as a factor as they were during the 2007 record low season.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from May 10, 2013:

 photo Antarctic_sea_ice_20130510_zps3bc7c6af.png

Figure 5UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130510.

And here is the corresponding graphic from June 13, 2013:

 photo Antarctic_sea_ice_20130613_zpsbe2cd3c3.png

Figure 6UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130613.

Sea ice growth in the past two months is within climatological norms.  However, there is more Antarctic sea ice today than there normally is on this calendar date.  The reason for this is the presence of early-season extra ice in the Weddell Sea (east of the Antarctic Peninsula that juts up toward South America).  This ice existed this past austral (Southern Hemisphere) summer due to an anomalous atmospheric circulation pattern: persistent high pressure west of the Weddell Sea.  This pressure system caused winds that pushed the sea ice north and also moved cold Antarctic air over the Sea, which kept ice melt rate well below normal.  A similar mechanism helped sea ice form in the Bering Sea last winter.  Where did the anomalous winds come from?  We can again point to a climatic relationship.

The difference between the noticeable and significant long-term Arctic ice loss and relative lack of Antarctic ice loss is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent in the 20th century.  This depletion has caused a colder southern polar stratosphere than it otherwise would be.  Why?  Because ozone heats the air around it after it absorbs UV radiation and re-radiates it to its environment.  Will less ozone, there is less stratospheric heating.  This process reinforced the polar vortex over the Antarctic Circle.  This is almost exactly the opposite dynamical condition than exists over the Arctic with the negative phase of the Arctic Oscillation.  The southern polar vortex has helped keep cold, stormy weather in place over Antarctica that might not otherwise would have occurred to the same extent and intensity. The vortex and associated anomalous high pressure centers kept ice and cold air over places such as the Weddell Sea this year.

As the “ozone hole” continues to recover during this century, the effects of global warming will become more clear in this region, especially if ocean warming continues to melt sea-based Antarctic ice from below (subs. req’d).  The strong Antarctic polar vortex will likely weaken back to a more normal state and anomalous high pressure centers that keep ice flowing into the ocean will not form as often.  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.  In the next few decades, we will have more than enough to contend with from Greenland ice sheet melt.  Were we to face a melting West Antarctic Ice Sheet at the same time, we would have to allocate many more resources.  Of course, in a few decades, we’re likely to face just such a situation.

Finally, here is the Antarctic sea ice extent time series through early June:

 photo S_stddev_timeseries_20130613_zpsaf473dbf.png

Figure 7NSIDC Antarctic sea ice extent time series through early June 2013.

The 2013 time series continues to track near the top of the +2 standard deviation envelope and above the 2012 time series.  Unlike the Arctic, there is no clear trend toward higher or lower sea ice extent conditions in the Antarctic Ocean.

Policy

Given the lack of climate policy development at a national or international level to date, Arctic conditions will likely continue to deteriorate for the foreseeable future.  This is especially true when you consider that climate effects today are largely due to greenhouse gas concentrations from 30 year ago.  It takes a long time for the additional radiative forcing to make its way through the climate system.  The Arctic Ocean will soak up additional energy (heat) from the Sun due to lack of reflective sea ice each summer.  Additional energy in the climate system creates cascading and nonlinear effects throughout the system.  For instance, excess energy pushes the Arctic Oscillation to a more negative phase, which allows anomalously cold air to pour south over Northern Hemisphere land masses while warm air moves over the Arctic during the winter.  This in turn impacts weather patterns throughout the year across the mid-latitudes and prevents rapid ice growth where we want it.

More worrisome for the long-term is the heat that impacts land-based ice.  As glaciers and ice sheets melt, sea-level rise occurs.  Beyond the increasing rate of sea-level rise due to thermal expansion (excess energy, see above), storms have more water to push onshore as they move along coastlines.  We can continue to react to these developments as we’ve mostly done so far and allocate billions of dollars in relief funds because of all the human infrastructure lining our coasts.  Or we can be proactive, minimize future global effects, and reduce societal costs.  The choice remains ours.

Errata

Here are my State of Polar Sea Ice posts from May and March 2013. For further comparison, here is my State of Polar Sea Ice post from May 2012.


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State of Polar Sea Ice – April 2013: Arctic Sea Ice Decline and Antarctic Sea Ice Gain

Global polar sea ice area in April 2013 tracked back to climatological normal conditions (1979-2009) from the temporary surplus the previous two months.  This follows January and February’s improvement from September 2012′s significant negative deviation from normal conditions (from -2.5 million sq. km. to +750,000 sq. km.).  While Antarctic sea ice gain was slightly more than the climatological normal rate following the austral summer, Arctic sea ice loss was slightly more than normal during the same period.

Arctic Sea Ice

According to the NSIDC, sea ice creation during April measured 1.5 million sq. km.  This melt rate was approximately normal for the month, so April′s extent remained below average again.  Instead of measuring near 15 million sq. km., April 2013′s average extent was only 14.37 million sq. km., a 630,000 sq. km. difference.  In terms of annual maximum values, 2013′s 15.13 million sq. km. was 733,000 lower than normal.

Barents Sea (Atlantic side) ice once again fell from its climatological normal value during the month after remaining low during most of the winter.  Kara Sea (Atlantic side) ice temporarily recovered from its wintertime low extent and reached normal conditions, which is also different from spring 2012′s conditions, before 2013 melt caused the extent to fall below normal conditions again.  The Bering Sea (Pacific side), which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012 through February 2013.  This caused anomalously high ice extent in the Bering Sea again this winter.  As it did previously this winter, an extended negative phase of the Arctic Oscillation allowed cold Arctic air to move far southward and brought warmer than normal air to move north over parts of the Arctic.  The AO’s tendency toward its negative phase in recent winters is related to the lack of sea ice over the Arctic Ocean in September each fall.  Warmer air slows the growth of ice, especially ice thickness.  This slow growth allows more melt than normal during the subsequent summer, which helps establish and maintain negative AO phases.  This is a destructive annual cycle for Arctic sea ice.

In terms of climatological trends, Arctic sea ice extent in April has decreased by 2.3% per decade, the lowest of any calendar month.  This rate is closest to zero in the late winter/early 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 (much 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 (e.g., 2011) – 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.

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State of Polar Sea Ice – March 2013: Annual Arctic Maximum and Antarctic Minimum Reached

For the second time in only six years, and the third time in ten years, global polar sea ice area in February and March 2013 mimicked climatological normal conditions (1979-2009).  This follows January’s improvement from September 2012’s significant negative deviation from normal conditions.  While Antarctic sea ice loss occurred slower than the climatological normal rate, Arctic sea ice gain was more rapid than normal during February.  Polar sea ice recovered from an extensive deficit of 2.5 million sq. km. area late last year to a 0.5 million sq. km. surplus within the last week.

Arctic Sea 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 than normal this winter.  Similar conditions occurred during the past six boreal winters.  Sea ice creation during February measured 766,000 sq. km.  Despite this rather rapid growth (38% higher than normal), February′s extent remained well below average for the month.  Instead of measuring near 15.64 million sq. km., February 2013′s average extent was only 14.66 million sq. km., a 980,000 sq. km. difference!  The Arctic likely reached its maximum annual extent about 10 days ago.  In terms of annual maximum values, 2013’s 15.13 million sq. km. was 733,000 lower than normal.February’s relatively high rate of ice formation for February related to the lack of existing sea ice at the beginning of the month.  Without ice already in the Ocean, new ice formed as winter continued.

Barents Sea (Atlantic side) ice finally edged toward its climatological normal value during the month after remaining low this winter, as it did in the past 10 winters.  Kara Sea (Atlantic side) ice recovered from low extent the past couple of months, which is different from February 2012’s conditions.  The Bering Sea (Pacific side), which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012 through February 2013.  This caused anomalously high ice extent in the Bering Sea again this winter.  As it did previously this winter, a negative phase of the Arctic Oscillation allowed cold Arctic air to move far southward and brought warmer than normal air to move north over parts of the Arctic.  The AO’s tendency toward its negative phase in recent winters is related to the lack of sea ice over the Arctic Ocean in September each fall.

In terms of climatological trends, Arctic sea ice extent in February has decreased by 2.9% per decade, the lowest of any calendar month.  This rate is closest to zero in the late winter/early 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 (much 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 (e.g., 2011) – 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 February 11, 2013:

 photo Arctic_sea_ice_20130211_zps0a8dd08b.png

Figure 1UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130211.

Here is the similar image from March 24, 2013:

 photo Arctic_sea_ice_20130325_zpsc64e9758.png

Figure 2UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130324.

As is normal for this time of year, there is not a large difference between these two graphics.  Any differences are primarily due to storm systems’ presence that push ice around, or the lack thereof.  The lack of sea ice in the Barents Sea (north of Europe) is problematic because wind and ocean currents typically pile sea ice up on the Atlantic side of the Arctic.  Sea ice presence in the Bering Sea (between Alaska and Russia) does not alleviate this problem because currents take ice from that area and transport it into the Arctic and then out into the Atlantic.  The sea ice on the Atlantic side would be among the first that currents transport and then melt during the spring.  With sea ice missing on the Atlantic side, currents will more easily transport Arctic sea ice to southern latitudes where it melts.

Many people questioned the overall health of the Arctic ice pack earlier this month when images (like the one below) and video documented extensive cracks in the ice in the Chukchi and Beaufort Seas.  A fellow blogger (and new author!) emailed me about this phenomenon and I wrote that I would blog my thoughts on the topic.  As Andrew Freedman wrote, “According to the National Snow and Ice Data Center (NSIDC) in Boulder, Colo., this fracturing event appears to be related to a storm that passed over the North Pole on Feb. 8, 2013, creating strong off-shore ice motion. The event is unusual but not unheard of, as similar patterns were seen in early 2011 and 2008. However, the NSIDC said the fracturing this time is more extensive.”  The worry is the extent and size of the cracks and leads as well as the early calendar date at which they are all appearing – up to weeks before normal.

I found this article on the topic and agree with Greg Laden, the author.  The cracks and leads  might be a big deal or they might not.  We will have to wait until the minimum sea ice extent occurs in September before we issue judgment.  The scientifically sound course of action would be to wait until early cracks appeared in multiple seasons and then see what the range of response later in the year is.  For all we know, the cracks could allow for even more ice to form in March than normal and delay the onset of melting.  It strikes me as scientifically unsound and even irresponsible to conjecture about the existence and effect of processes, which we do not understand well.  If scientists crow about upcoming devastating Arctic sea ice loss this year and reality doesn’t conform to their wishes, how much credibility with the public do they engender?  I think observers should stay patient and discuss the phenomena and effects we do understand – there is plenty of material with which to work!

 photo Arctic-sea-ice-sat-pic-20130312_zpsd8fe90e9.jpg

Figure 3 – NOAA AVHRR infrared picture of Arctic sea ice on 20130312.

The following graph of Arctic ice volume from the end of February demonstrates:

 photo SeaIceVolumeAnomaly_20130228_zps1777b889.png

Figure 4PIOMAS Arctic sea ice volume time series through February 2013.

As the graph shows, volume (length*width*height) hit another record minimum in June 2012.  Moreover, the volume remains far from normal since it just returned to the -2 standard deviation envelope (light gray).  I understand that most readers don’t have an excellent handle on statistics, but conditions between -1 and -2 standard deviations are rare and conditions outside the -2 standard deviation threshold (see the line below the shaded area on the graph above) are incredibly rare: the chances of 3 of them occurring in 3 subsequent years under normal conditions are extraordinarily low (you have a better chance of winning the Powerball than this).  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries; a new normal is developing.  Note further that the ice volume anomaly returned to near the -1 standard deviation envelope in early 2011, early 2012, and now early 2013.  In each of the previous two years, volume fell rapidly outside of the -2 standard deviation area with the return of summer.  That means that natural conditions are not the likely cause; rather, another cause is much more likely to be responsible for this behavior: human influence.

Arctic Sea Ice Extent

Take a look at February’s areal extent time series data:

 photo N_stddev_timeseries_20130325_zps9c8c87bc.png

Figure 5NSIDC Arctic sea ice extent time series through late March 2013 compared with last five years’ data and climatological norm (dark gray line) and standard deviation envelope (light gray).

As you can see, this year’s extent (light blue cuve) grew more rapidly in December than February.  This graph also shows that this year’s extent remained at historically low levels through the winter, well below average values (thick gray curve), just as it did in the previous five winters, which are also shown on this graph.  In this month’s version, NSIDC also plotted the previous four years’ data (2008 through 2012).  You can also see what happened to conditions during late March and early April last spring (dark green curve).  A late season freeze surge occurred, which delayed the date of maximum extent by a number of weeks.  Last year’s surge has no bearing on what might happen over the next couple of weeks this year.  Weather conditions and some low-frequency climate oscillations (AO) are different this year and have more bearing on ice conditions than last year’s date of maximum extent.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from February 11, 2013:

 photo Antarctic_sea_ice_20130211_zps2eff7662.png

Figure 6UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130211.

And here is the corresponding graphic from March 24, 2013:

 photo Antarctic_sea_ice_20130325_zpsbb795acd.png

Figure 7UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130324.

Ice growth is easily visible around the continent.  There is more Antarctic sea ice today than there normally is on this date in the year.  The reason for this is the extra ice in the Weddell Sea (east of the Antarctic Peninsula that juts up toward South America).  This ice exists this austral summer due to an anomalous atmospheric circulation pattern: persistent high pressure west of the Weddell sea pushed sea ice north.  The same winds that pushed the sea ice north also moved cold Antarctic air over the Sea, which has kept ice melt rate well below normal.  A similar mechanism helped sea ice form in the Bering Sea so far this winter.  Where did the anomalous winds come from?  We can again point to a climatic relationship.

The difference between the noticeable and significant long-term Arctic ice loss and relative lack of Antarctic ice loss is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent in the 20th century.  This depletion has caused a colder southern polar stratosphere than it otherwise would be, reinforcing the polar vortex over the Antarctic Circle.  This is almost exactly the opposite dynamical condition than exists over the Arctic with the negative phase of the Arctic Oscillation.  The southern polar vortex has helped keep cold, stormy weather in place over Antarctica that might not otherwise would have occurred to the same extent and intensity. The vortex and associated anomalous high pressure centers kept ice and cold air over places such as the Weddell Sea this year.

As the “ozone hole” continues to recover during this century, the effects of global warming will become more clear in this region, especially if ocean warming continues to melt sea-based Antarctic ice from below (subs. req’d).  The strong Antarctic polar vortex will likely weaken back to a more normal state and anomalous high pressure centers that keep ice flowing into the ocean will not form as often.  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.  In the next few decades, we will have more than enough to contend with from Greenland ice sheet melt.  Were we to face a melting West Antarctic Ice Sheet at the same time, we would have to allocate many more resources.  Of course, in a few decades, we’re likely to face just such a situation.

Finally, here is the Antarctic sea ice extent time series through mid-March:

 photo S_stddev_timeseries_20130325_zpsf34ff5a5.png

Figure 8NSIDC Antarctic sea ice extent time series through late March 2013.

Policy

Given the lack of climate policy development to date, Arctic conditions will likely continue to deteriorate for the foreseeable future.  The Arctic Ocean will soak up additional energy (heat) from the Sun due to lack of reflective sea ice.  Additional energy in the climate system creates cascading and nonlinear effects throughout the system.  For instance, excess energy pushes the Arctic Oscillation to a more negative phase, which allows anomalously cold air to pour south over Northern Hemisphere land masses while warm air moves over the Arctic during the winter.  This in turn impacts weather patterns throughout the year across the mid-latitudes.

More worrisome for long-term concerns is the heat that impacts land-based ice.  As glaciers and ice sheets melt, sea-level rise occurs.  Beyond the increasing rate of sea-level rise due to thermal expansion (excess energy, see above), storms have more water to push onshore as they move along coastlines.  We can continue to react to these developments as we’ve mostly done so far and allocate billions of dollars in relief funds because of all the human infrastructure lining our coasts.  Or we can be proactive, minimize future global effects, and reduce societal costs.  The choice remains ours.

Errata

Here are my State of Polar Sea Ice posts from February and January 2013. For further comparison, here is my State of Polar Sea Ice post from March 2012.

Update

I meant to include the following two graphs in this post because of the historical nature they represent.

 photo Arctice_sea_ice_area_20120918_2_zps7e4bc6a2.png

Figure 9 – Time series of Arctic sea ice area from UIUC from 1979 to Sep. 18, 2012.

 photo Arctic_sea_ice_area_20130326_zps5d70869e.png

Figure 10 – Time series of Arctic sea ice area from UIUC from 1979 to Mar. 25, 2013.

The difference between these two graphics is obvious since they were taken near the time of minimum area (2012) and maximum area (2013).  In terms of magnitude, the freeze season of 2012-2013 produced the highest amount of frozen ice area in the modern record (11.168 million sq. km.).  The value of ice area last September was the lowest on record and the value of ice area earlier this month was the highest in four years.  March’s area value occurred because of the factors I discussed above that boil down to this: the relative lack of thick ice in recent winters permitted rapid ice growth, albeit thin ice that melts quickly the following year.  In addition to new record low area values in the future, significant oscillations from minimum to maximum and back again are likely to occur in the future as well.  This does not contradict climate change; it is a manifestation of climate change.  I hope write more about this topic soon, but countries are reconstructing international policy (military and economic) as a result of the changes seen in the Arctic.  Those policy shifts will have societal repercussions, which I venture say few people realize today.


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

Global polar sea ice area in early February 2013 mimics climatological normal conditions (1979-2009), after improvement in the past month.  Antarctic sea ice loss is occurring slower than the climatological normal rate.  Arctic sea ice gain is more rapid than normal.  Polar sea ice recovered from an extensive deficit of -2.5 million sq. km. area late last year to near-zero anomaly within the last week.

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 than normal.  Similar conditions occurred during the past six boreal winters.  Sea ice creation during January measured 1.36 million sq. km.  Despite this rather rapid growth, January′s extent remained well below average for the month.  Instead of measuring near 14.84 million sq. km., January 2013′s extent was only 13.78 million sq. km., a 1.06 million sq. km. difference!  The Barents Sea recorded lower than average sea ice, which is an unusual condition for January.  Kara Sea ice recovered from low extent the past couple of months.  The Bering Sea, which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012 and January 2013.  This has caused anomalously high ice extent in the Bering Sea.  Previously this winter, a negative phase of the Arctic Oscillation allowed cold Arctic air to move far southward and brought warmer than normal air to move north over parts of the Arctic.  The AO has returned to a more neutral phase in the past month, which has kept Arctic air closer to where it normally is this time of year.

In terms of longer, climatological trends, Arctic sea ice extent in January has decreased by 3.2% 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 (e.g., 2011) – 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 January 9, 2013:

Photobucket

Figure 1UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130109.

Here is the similar image from February 11th 2013:

 photo Arctic_sea_ice_20130211_zps0a8dd08b.png

Figure 2UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130211.

The lack of sea ice in the Barents Sea (north of Europe) is problematic because wind and ocean currents typically pile sea ice up on the Atlantic side of the Arctic.  Sea ice presence in the Bering Sea (between Alaska and Russia) does not alleviate this problem because currents take ice from that area and transport it into the Arctic.  That sea ice will be among the first to melt completely come spring.  With sea ice missing on the Atlantic side, currents will more easily transport Arctic sea ice to southern latitudes where it melts.

Overall, the health of the ice pack is not healthy, as the following graph of Arctic ice volume from the end of January demonstrates:

 photo SeaIceVolumeAnomaly_20130131_zps54d600f7.png

Figure 3PIOMAS Arctic sea ice volume time series through January 2013.

As the graph shows, volume (length*width*height) hit another record minimum in June 2012.  Moreover, the volume remains far from normal since it just returned to the -2 standard deviation envelope (light gray).  I understand that most readers don’t have an excellent handle on statistics, but conditions between -1 and -2 standard deviations are rare and conditions outside the -2 standard deviation threshold (see the line below the shaded area on the graph above) are incredibly rare: the chances of 3 of them occurring in 3 subsequent years under normal conditions are extraordinarily low (you have a better chance of winning the Powerball than this).  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries; a new normal is developing.  Note further that the ice volume anomaly returned to near the -1 standard deviation envelope in early 2011, early 2012, and now early 2013.  In each of the previous two years, volume fell rapidly outside of the -2 standard deviation area with the return of summer.  That means that natural conditions are not the likely cause; rather, another cause is much more likely to be responsible for this behavior: human influence.

Arctic Sea Ice Extent

Take a look at January’s areal extent time series data:

 photo N_stddev_timeseries_20130211_zpsfdf23a52.png

Figure 4NSIDC Arctic sea ice extent time series through early February 2013.

As you can see, the extent (light blue line) grew rapidly in November but still remained at historically low levels through the winter.  The extent remained well below average values (thick gray line) throughout the fall and early winter.  The time series of sea ice extent for previous low years is also shown on this graph.  In this month’s version, NSIDC also plotted the previous four years’ data.  You can see the effect of the wintertime conditions that I described above: the difference between a year’s extent and the average value in January or February is smaller than the difference in October.  This leads us to examine the differences between the historical mean, the negative two standard deviation (light gray) below that mean, and the 2012-2013 time series.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from January 9, 2013:

Photobucket

Figure 5UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130109.

And here is the corresponding graphic from February 11th:

 photo Antarctic_sea_ice_20130211_zps2eff7662.png

Figure 6UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130211.

Ice loss is easily visible around the continent.  There is slightly more Antarctic sea ice today than there normally is on this date in the year.  The reason for this is the extra ice in the Weddell Sea (east of the Antarctic Peninsula that juts up toward South America).  This ice exists this winter due to an anomalous atmospheric circulation pattern: persistent high pressure west of the Weddell sea pushed sea ice north.  The same winds that pushed the sea ice north also moved cold Antarctic air over the Sea, which has kept ice melt rate well below normal.  A similar mechanism helped sea ice form in the Bering Sea so far this winter.

As a reminder, the difference between long-term Arctic ice loss and relative lack of Antarctic ice loss is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent in the 20th century.  This depletion has caused a colder southern polar stratosphere than it otherwise would be, reinforcing the polar vortex over the Antarctic Circle.  This is almost exactly the opposite dynamical condition than exists over the Arctic with the negative phase of the Arctic Oscillation.  The southern polar vortex has helped keep cold, stormy weather in place over Antarctica that might not otherwise would have occurred to the same extent and intensity.  As the “ozone hole” continues to recover during this century, the effects of global warming will become more clear in this region, especially if ocean warming continues to melt sea-based Antarctic ice from below (subs. req’d).  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.  In the next few decades, we will have more than enough to contend with from melting on Greenland.  Were we to face melting West Antarctic Ice Sheet at the same time, we would have to allocate many more resources.  Of course, in a few decades, we’re likely to face just such a situation.

Finally, here is the Antarctic sea ice extent time series from February 11th:

 photo S_stddev_timeseries_20130211_zpsad16917a.png

Figure 7NSIDC Antarctic sea ice extent time series through early February 2013.

Policy

Given the lack of climate policy development to date, Arctic conditions will likely continue to deteriorate for the foreseeable future.  The Arctic Ocean will soak up additional energy from the Sun due to lack of reflective sea ice.  Additional energy in the climate system creates cascading effects through the system.  The energy pushes the Arctic Oscillation to a negative phase, which allows anomalously cold air to pour south over Northern Hemisphere land masses while warm air moves over the Arctic.  This impacts weather patterns throughout the year.

More worrisome for long-term concerns is the heat that impacts land-based ice.  As glaciers and ice sheets melt, sea-level rise occurs.  Beyond the increasing rate of sea-level rise, storms have more water to push onshore as they move along coastlines.  We can continue to react to these developments as we’ve mostly done so far.  Or we can be proactive, minimize future global effects, and reduce societal costs.  The choice remains ours.

Errata

Here are my State of the Poles posts from January and September.

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