State of the Poles – June 2012: Arctic Ice Extent Below Normal; Antarctic Ice Near Climatological Normal

The state of global polar sea ice area in early June 2012 has once again fallen below climatologically normal conditions (1979-2009).  Arctic sea ice loss is primarily responsible for this change in condition since just last month.  Arctic sea ice melted quickly in May because it was thinner than usual; Antarctic sea ice has refrozen at a near normal rate during the late austral autumn.  Polar sea ice recovered from an extensive deficit of -2 million sq. km. area three months ago to a +750,000 sq. km. anomaly one to two months ago before falling back to a -1 million sq. km. deficit.  After starting the year at a deficit last year, sea ice area spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era in 2011.  Generally poor environmental conditions established and maintained this condition, predominantly across the Arctic last year.  The last time global sea ice area remained near 19 million sq. km. through May was in 2007, when the Arctic extent hit its modern day record minimum.

Arctic Ice

According to the NSIDC, weather conditions during the latter part of the previous winter and spring were less conducive for Arctic sea ice freezing on the Atlantic side of the Arctic while conditions were more conducive than usual for freezing on the Pacific side.  Sea ice melt during May was more than normal: 1.62 million sq. km. instead of 1.38 million sq. km.  As such, May′s extent was below average for the month in the satellite record.  Arctic sea ice extent on in May averaged 13.13 million sq. km.  Barents and Kara Sea ice remained very much below normal, more so than in recent years.  The Bering Sea, which saw ice extent growth due to anomalous northerly winds in previous months, instead witnessed above normal conditions.  Overall, near surface temperatures were warmer than average across the Arctic Ocean.

In terms of longer, climatological trends, Arctic sea ice extent in May has decreased by -2.3% per decade.  This rate is lowest in the spring months than the late summer 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.  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 are 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.

Arctic Pictures and Graphs

The following graphic is a satellite representation of Arctic ice as of April 28, 2012:

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120428.

Compare this with June 7th’s satellite representation, also centered on the North Pole:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120607.

The sea ice in the Bering Sea, as mentioned above, formed more quickly and to a further southern extent than is normally seen, but has largely melted already due to the ice’s young age and thin depth.  What remained missing this winter and early spring was the sea ice north of Scandinavia.  This is the result of anomalously warm waters from the Gulf Stream being drawn further north than is normal.  This is due to the positive AO index & NAO index during the last boreal winter and spring.  As a side note, this phenomenon combined with the most recent, moderate La Niña in the Pacific Ocean has led to Dec-May being anomalously warm and dry for most of the U.S.  Indeed, this year has been the warmest Jan-May period on record in the US, as I will detail in a separate post.

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

Figure 3 – PIOMAS Arctic sea ice volume time series through May 2012.

As the graph shows, volume hit a record minimum earlier in 2011 before returning to the -2 standard deviation envelope.  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 2 of them occurring in 2 subsequent years under normal conditions are very, very remote indeed.  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries.  Note further that after conditions returned to near the -1 standard deviation envelope in late 2011/early 2012, volume has once again fallen rapidly outside of the -2 standard deviation area.  The chances that this would happen three separate times in three consecutive years is exceptionally remote.  That means that natural conditions are not the likely cause; rather, another cause is much more likely to be responsible for this behavior.

Switching back from volume to area, take a look at May’s areal extent time series data:

Figure 4 – NSIDC Arctic sea ice extent time series through early June 2012.

This winter allowed the extent to do something it had not done for the most recent handful of winters: a return of ice extent to within the -2 standard deviation envelope.  Indeed, the extent in April briefly matched average conditions before a relatively warm spell melted ice quickly in mid-April.  The reason for this is a shift in wind conditions: speed and direction both changed from late winter through this last month.  Those winds piled sea ice up instead of pushing it apart.  The disadvantage: ice extent decreased, as seen in Figure 4.  The advantage: ice volume grew, as seen in Figure 3.  The effect on this September’s minimum extent will indicate how helpful the early season winds were in building sea ice that doesn’t melt every year back up.  During May, as I wrote above, melting occurred at a slightly faster rate than normal, resulting in a return to near-record low extent conditions.

Occasionally, I also like to include a supplemental time series graph that the NSIDC report contains.  Here is this month’s supplemental graph:

Figure 5 – NSIDC Arctic sea ice extent time series of ice extent conditions comparing previous years’ data and 2012 data through May.

This graph contains all of the same data as the previous graph and adds the time series lines from the previous 5 winters.  As you can see, extent varies during the same month from year to year.  The recent decline in extent, caused by a change in wind direction and speed, has reduced Arctic ice extent back to ~13 million sq. km., which is well below normal for May.  The past three winters also saw similar magnitude reductions through May, although the starting and ending values were obviously different.  Despite these differences in subsequent years, the minimum ice extent values were quite similar: at or near the record low set in 2007.  Will fall 2012 be any different or will the surge in ice growth on the Pacific side of the Arctic help to stave off the worst effects seen in the past five years?

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from April 28th:

Figure 6 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120607.

Compare that graphic with the same view from June 7th:

Figure 7 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120607.

Ice gain is easily visible around the continent.  As a reminder, this 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.  That 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.  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.

Finally, here is the Antarctic sea ice extent time series from June 7th:

Figure 8 – NSIDC Antarctic sea ice extent time series through early June 2012.

Antarctic sea ice extent had remained above average to some extent through the austral summer and early spring, which is good news.  The difference in conditions from the first part of 2011 to the similar time period in 2012 is obvious: NSIDC measured last year’s extent near the bottom of the standard deviation envelope while this year’s extent is much healthier.  Despite the shift in preceding conditions, extent in May 2011 and 2012 returned to normal.

Errata

Here are my State of the Poles posts from May and March.

You can find NSIDC’s June report here.

NASA & NOAA: April 2012 Among Top 5 Warmest On Record

According to data released by NASA and NOAA this month, April 2012 ranked among the top 5 warmest Aprils on record: NASA recorded the 4th (tied) warmest April in its dataset; NOAA recorded the 5th warmest April in its dataset.  The two agencies have slightly different analysis techniques, which actually helps to reinforce the results from each other.

The details:

April’s global average temperatures were 0.56°C above normal (1951-1980), according to NASA.  The warmest regions on Earth are exactly where climate models have been projecting the most warmth to occur for years: high latitudes (especially within the Arctic Circle in April 2012).  The past three months have a +0.47°C temperature anomaly.  And the latest 12-month period (May 2011 – Apr 2012) had a +0.49°C temperature anomaly.

According to NOAA, April’s global average temperatures were 0.65°C (1.17°F) above the 20th century mean of 13.7°C (56.7°F).  NOAA’s global temperature anomaly map for April reinforces the message: high latitudes continue to warm at a faster rate than the mid- or low-latitudes.  The extreme warmth over Siberia is especially worrisome due to the vast methane reserves locked into the tundra and under the seabed near the region.  Methane is a stronger greenhouse gas than carbon dioxide,which is the leading cause of the warmth we’re now witnessing.  As I discussed in the comments in a recent post, the warming signal from methane likely hasn’t been captured yet since the yearly natural variability and the CO2-caused warming signals are much stronger.  It is likely that we will not detect the the methane signal for many more years.

State of the Poles – May 2012: Arctic Ice Extent Near Normal; Antarctic Ice Returning To Normal

The state of global polar sea ice area in early May 2012 has convincingly returned to climatologically normal conditions (1979-2009).  Arctic sea ice recovered to near-normal conditions after a late start to the freeze season and a late-season slowdown due to certain atmospheric and oceanographic conditions; Antarctic sea ice has melted only slightly more slowly than is normal during the austral autumn.  Put another way, polar sea ice has recovered from an extensive deficit of -2 million sq. km. area a couple of months ago to a +750,000 sq. km. anomaly today.  That said, sea ice area spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era in 2011.  Generally poor environmental conditions established and maintained this condition, predominantly across the Arctic last year.

Arctic Ice

According to the NSIDC, weather conditions this winter and early spring were slightly less conducive for Arctic sea ice freezing on the Atlantic side of the Arctic while conditions were more conducive than usual for freezing on the Pacific side.  Melting during April was slightly less than normal: 1.07 million sq. km. instead of 1.21 million sq. km.  As such, April′s extent was the near average for the month in the satellite record.  Arctic sea ice extent on in April averaged 14.73 million sq. km.  Barents Sea ice remained below normal, as it did in recent years.  The Bering Sea, which saw ice extent growth due to anomalous northerly winds in previous months, instead witnessed more normal conditions.  Overall, near surface temperatures were warmer than average across the Arctic Ocean.

In terms of longer, climatological trends, Arctic sea ice extent in April has decreased by -2.6% per decade.  This rate is lowest in the winter months than the late summer 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.  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 are 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.

Arctic Pictures and Graphs

The following graphic is a satellite representation of Arctic ice as of March 9, 2012:

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120309.

Compare this with April 28th’s satellite representation, also centered on the North Pole:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120428.

Once Hudson Bay finally froze over around the time of the New Year, ice extent grew toward the Atlantic Ocean.  The sea ice in the Bering Sea, as mentioned above, formed more quickly and to a further southern extent than is normally seen.  What remained missing this winter and early spring is the sea ice north of Scandinavia.  This is the result of anomalously warm waters from the Gulf Stream being drawn further north than is normal.  This is due to the positive AO & NAO indices during this winter.  As a side note, this phenomenon combined with the moderate La Nina in the Pacific Ocean has led to Dec-Apr being an anomalously warm and dry month for most of the U.S. in March and April.

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

Figure 3 – PIOMAS Arctic sea ice volume time series through April 2012.

As the graph shows, volume hit a record minimum earlier in 2011 before returning to the -2 standard deviation envelope.  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 2 of them occurring in 2 subsequent years under normal conditions are very, very remote.  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries.

Switching back from volume to area, take a look at April’s areal extent time series data:

Figure 4 – NSIDC Arctic sea ice extent time series through mid-May 2012.

This winter allowed the extent to do something it had not done for the most recent handful of winters: a return of ice extent to within the -2 standard deviation envelope.  Indeed, the extent in April briefly matched average conditions before a relatively warm spell melted ice quickly in mid-April.  The reason for this is a shift in wind conditions: speed and direction both changed from late winter through this last month.  Those winds piled sea ice up instead of pushing it apart.  The disadvantage: ice extent decreased, as seen in Figure 4.  The advantage: ice volume grew, as seen in Figure 3.  The effect on this September’s minimum extent will indicate how helpful the early season winds were in building sea ice that doesn’t melt every year back up.

Occasionally, I also like to include a supplemental time series graph that the NSIDC report contains.  Here is this month’s supplemental graph:

Figure 5 – NSIDC Arctic sea ice extent time series through April 2012.

This graph contains all of the same data as the previous graph and adds the time series lines from the previous 5 winters.  As you can see, extent varies during the same month from year to year.  The recent decline in extent, caused by a change in wind direction and speed, has reduced Arctic ice extent back to ~14 million sq. km., which is near normal for late April.  The past three winters also saw similar magnitude reductions near the end of April, though the starting and ending values were obviously different.  Despite these differences in subsequent years, the minimum ice extent values were quite similar: at or near the record low set in 2007.  Will fall 2012 be any different or will the surge in ice growth on the Pacific side of the Arctic help to stave off the worst effects seen in the past five years?

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from March 9th:

Figure 6 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120309.

Compare that graphic with the same view from April 28th:

Figure 7 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120428.

Ice gain is easily visible around the continent, especially east of the Antarctic Peninsula.  Conditions of Antarctic sea ice remain strong this year.  As a reminder, this is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent.  This depletion has caused a colder southern polar stratosphere than it otherwise would be, reinforcing the polar vortex over the Antarctic Circle.  That 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.  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.

Here is the Antarctic sea ice extent time series from mid-May:

Figure 8 – NSIDC Antarctic sea ice extent time series through mid-May 2012.

Antarctic sea ice extent has remained above average to some extent for months now, which is good news.  The difference in conditions from the first part of 2011 to the similar time period in 2012 is obvious: NSIDC measured last year’s extent near the bottom of the standard deviation envelope while this year’s extent is much healthier.

Errata

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

You can find NSIDC’s May report here.

State of the Poles – Mar 2012: Arctic Winds Shift Ice Extent; Antarctic Ice Near Average

The state of global polar sea ice area in early January 2012 has convincingly returned to climatologically normal conditions (1979-2009).  Arctic sea ice has recovered very quickly after a late start to the freeze season and a late-season slowdown due to certain atmospheric and oceanographic conditions; Antarctic sea ice has melted only slightly more slowly than is normal during the austral summer.  Put another way, polar sea ice has recovered from an extensive deficit of -2 million sq. km. area a couple of months ago to zero anomaly today.  That said, sea ice area spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era.  Generally poor environmental conditions established and maintained this condition, predominantly across the Arctic this year.

Arctic Ice

According to the NSIDC, weather conditions this winter were slightly less conducive for Arctic sea ice freezing on the Atlantic side of the Arctic while conditions were more conducive for freezing on the Pacific side.  As such, February′s extent was the 5th lowest on record.  Additionally, Arctic sea ice extent on in February averaged just 14.56 million sq. km.  Sea ice extent was well below average in the Barents Sea due to temperatures that were 7-14°F above normal!  The Bering and Baffin Seas meanwhile saw ice extent and ice growth, respectively, above normal during the month.

During February, Arctic sea ice refroze more rapidly than is the case for most Februaries.  February’s sea ice extent increased by 956,000 sq. km., almost 2X the normal rate – largely due to previously low ice extent conditions in the Baffin Sea.  Specific conditions around the Arctic Ocean were highly influenced by the positive phase of the North Atlantic Oscillation.

In terms of longer, climatological trends, Arctic sea ice extent in February has decreased by -3% per decade.  This rate is lowest in the winter months than the late summer 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.  Additional low ice seasons will continue.  Some years will see less decline than other years – 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 a new normal is being established 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 7, 2012:

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120107.

Compare this with March 9th’s satellite representation, also centered on the North Pole:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120309.

Once Hudson Bay finally froze over around the time of the New Year, ice extent grew toward the Atlantic Ocean.  The sea ice in the Bering Sea, as mentioned above, formed more quickly than is normal.  What is largely still missing is the sea ice north of Scandinavia.  This is the result of anomalously warm waters from the Gulf Stream being drawn further north than is normal.  This is due to the positive AO & NAO indices during this winter.  As a side note, this phenomenon combined with the moderate La Nina in the Pacific Ocean has led to Dec-Mar being a warm and dry month for most of the U.S. so far

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

Figure 3 – PIOMAS Arctic sea ice volume time series through February 2012.

As the graph shows, volume hit a record minimum earlier in 2011 before returning to the -2 standard deviation envelope.  I know most folks don’t have a very good 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 2 of them occurring in 2 subsequent years under normal conditions are very, very remote.  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries.

Switching back from volume to area, take a look at February’s areal extent time series data:

Figure 4 – NSIDC Arctic sea ice extent time series through early March 2012.

As you can see, the sea ice extent has spent all of the fall and early winter well outside of the -2 standard deviation envelope, just as it has for 5 winters in a row.  It cannot be stated otherwise: these conditions are not indicative of a healthy system.  This winter brought something new that the past few winters did not, however a return of ice extent to within the -2 standard deviation envelope.  The reason for this is a shift in wind conditions: speed and direction both changed from early winter through this last month.  Those winds pushed sea ice apart instead of piling it up.  The advantage: ice extent increased, as seen in Figure 4.  The disadvantage: ice volume stopped growing, as seen in Figure 3.  The effect on this September’s minimum extent will indicate how helpful the early season winds were in building sea ice that doesn’t melt every year back up.

Occasionally, I also like to include a supplemental time series graph that the NSIDC report contains.  Here is this month’s supplemental graph:

Figure 5 – NSIDC Arctic sea ice extent time series through early March 2012.

This graph contains all of the same data as the previous graph and adds time series from 4 of the previous 5 winters.  As you can see, extent varies during the same month from year to year.  The recent surge in extent, caused by a change in wind direction and speed, has brought Arctic ice extent up to ~15 million sq. km., which is challenging the highest extent in the most recent 6 winters.  The maximum 2007 and 2011 ice extent didn’t come close to 15 million sq. km. while 2010 achieved approximately the same value almost a full month later.  Despite these differences in subsequent years, the minimum ice extent values were quite similar: at or near the record low set in 2007.  Will fall 2012 be any different?

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from January 7th:

Figure 6 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120107.

Compare that graphic with the same view from March 9th:

Figure 7 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120309.

Ice loss is less easily visible around the continent in these two images than they were between previous months.  High ice concentrations remain well into the austral summer (nearly fall) east of the Antarctic Peninsula (the land mass that “points” to South America).  Conditions of Antarctic sea ice remain good this year.  As a reminder, this is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent.  This depletion has caused the southern polar stratosphere to be colder than it otherwise would be, reinforcing the polar vortex over the Antarctic Circle.  That 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.  For now, we should perhaps consider the relative fortune the lack of ozone has produced.

Here is the Antarctic sea ice extent time series from February:

Figure 8 – NSIDC Antarctic sea ice extent time series through early March 2012.

Melt rates have been at or near normal throughout the austral summer this year.  Year-to-year variation is also present in this graph, which includes the previous winter’s extent as a comparison.  At this point, no news is good news.  The Arctic is providing more than enough excitement for the time being.

Errata

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

You can find NSIDC’s January report here.

Cross-posted at SquareState.

State of the Poles – Jan 2012: Arctic Ice Near Historic Lows; Antarctic Ice Above Average

The state of global polar sea ice area in early January 2012 has temporarily returned to climatologically normal conditions (1979-2009).  Arctic sea ice has recovered very quickly after starting the freeze season slowly and Antarctic sea ice has melted more slowly than is normal for this time of year.  Put another way, polar sea ice has recovered from an extensive deficit of -2 million sq. km. area a couple of months ago to no anomaly today.  That said, sea ice area spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era.  Generally poor environmental conditions established and maintained this condition, predominantly across the Arctic, this year.

Arctic Ice

According to the NSIDC, weather conditions this fall were slightly less conducive for Arctic sea ice melt than was the case in 2007, the year that witnessed the record low extent.  As such, December 2011′s extent was the 3rd lowest on record.  Additionally, Arctic sea ice extent on December 31st measured just 13.25 million sq. km.  That was only 561,000 sq. km. more than the 2010 record low extent.  Because the dipole anomaly didn’t set up in the same way or with the same intensity as in 2007, Arctic sea ice extent has measured slightly higher than record minima in recent months.  We can’t count on these types of weather variations in the future, of course.  Another reason ice extent was low but didn’t set another record was the difference in ice motion: sea ice was likelier to remain in the Arctic in 2011 than in 2007 or 2010.

Since September’s record low, Arctic sea ice has refrozen rapidly.  December’s sea ice extent increased by 2.37 million sq. km. (vs. 1.86 million sq. km. average).  This situation mimics that of recent years after ice extent reaches low values in September and the sun sets for the winter.  The ocean released massive amounts of heat to the atmosphere, especially this fall since the AO index has been extremely positive.  This has caused cold air from the continents to be bottled up in a stronger vortex than normal and has drawn heat from the Arctic Ocean as it passes over the warmer fluid.

In terms of longer, climatological trends, Arctic sea ice extent in December has decreased by -3.5% per decade  These rates are more negative this year than the previous year (a trend that has continued).  These rates also use 1979-2000 as the climatological normal.  There is no reason to expect these rates to change significantly any time soon.  Additional low ice seasons will continue.  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 the establishment of a new normal in the Arctic is occurring.  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 December 12, 2011:

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20111212.

Compare this with January 7th’s satellite representation, also centered on the North Pole:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120107.

Hudson Bay finally froze over completely.  The sea ice in the Bering Sea formed normally.  What is missing is the sea ice north of Scandinavia.  This is the result of anomalously warm waters from the Gulf Stream being drawn further north than is normal.  This is due to the exceptionally positive AO index during the past couple of months.  As a side note, this phenomenon combined with the moderate La Nina in the Pacific Ocean has led to January being a warm and dry month for most of the U.S. so far.  The AO index is returning to more normal values now, so cold air outbreaks will become more likely in February.

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

Figure 3 – PIOMAS Arctic sea ice volume time series through December 2011.

As the graph shows, volume hit a record minimum earlier in 2011 before returning to the -2 standard deviation envelope.  I know most folks don’t have a very good 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 2 of them occurring in 2 subsequent years under normal conditions are very, very remote.  Hence the assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries.

Switching back from volume to area, take a look at December’s areal extent time series data:

Figure 4 – NSIDC Arctic sea ice extent time series through early January 2012.

As you can see, the sea ice extent has spent all of the fall and early winter well outside of the -2 standard deviation region, just as it has for 5 winters in a row.  It cannot be stated otherwise: these conditions are not indicative of a healthy system.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from December 12th:

Figure 5 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20111212.

Compare that graphic with the same view from January 7th:

Figure 6 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120107.

Ice loss is easily visible around the continent.  High ice concentrations remain well into the austral spring east of the Antarctic Peninsula (the land mass that “points” to South America).  Conditions of Antarctic sea ice remain good this year.

Here is the Antarctic sea ice extent time series from December:

Figure 7 – NSIDC Antarctic sea ice extent time series through early January 2012.

After conditions caused a slowdown in melt in late November and early December, the remainder of December and January was marked by normal ice melt rates.  At this point, no news is good news.  The Arctic is providing more than enough excitement for the time being.

Errata

Here are my State of the Poles posts from December and August.

You can find NSIDC’s January report here.

Cross-posted at SquareState.

State of the Poles – Dec 2011: Arctic Ice Continues Low; Antarctic Ice Above Average

I haven’t written about polar ice conditions for a few months due to lack of time thanks to school.  Hopefully my time availability moving forward will be high enough to keep this series going.

The state of global polar sea ice area in early December 2011 has temporarily returned to near climatologically normal conditions (1979-2009).  Arctic sea ice has recovered very quickly after starting the freeze season slowly and Antarctic sea ice is benefiting from weather conditions preventing extensive melt at the edges in much the same way as it did last year at the same time.  Since my last post (covering August conditions), polar sea ice has generally recovered from an extensive deficit of negative 2 million sq. km.  The long time that sea ice area spent near this dramatic condition is unprecedented in the modern era.  Poor conditions established this development across the Arctic this year.

Arctic Ice

According to the NSIDC, weather conditions this fall were slightly less conducive for Arctic sea ice melt than was the case in 2007, when the record low extent was recorded.  As such, 2011′s extent was the 2nd lowest on record.  Specifically, Arctic sea ice extent measured on 4.33 million sq. km. on September 9th.  That was only 160,000 sq. km. more than the 2007 record low extent (about 3.7% of the minimum extent measured this year, a very small difference by comparison).  For additional perspective, 2011′s minimum was 2.38 million sq. km. less than the 1979-2000 average yearly minimum.  My prediction that 2011 wouldn’t miss 2007′s record by much unfortunately turned out to be true.  One reason 2011′s minimum didn’t set a record was because the dipole anomaly didn’t set up in the same way or with the same intensity as 2007′s.  We can’t count on these types of weather variations to disallow record lows in the future, of course.  Another reason was the difference in ice motion: sea ice was likelier to remain in the Arctic in 2011 than in 2007.

Since September’s record low, Arctic sea ice has refrozen rather rapidly.  September’s average sea ice extent was 4.61 million sq. km. (vs. 7.04 million sq. km. average).  October’s average sea ice extent was 7.10 million sq. km. (vs. 9.29 million sq. km. normally).  November’s average was 10.01 million sq. km. (vs. 11.31 million sq. km.).  During the fall, sea ice extent remained near record lows set per month in years past (2007 & 2010).

In terms of longer, climatological trends, Arctic sea ice extent in September has decreased by -12% per decade; in October has decreased by -6.6% per decade; in November by -4.7% per decade.  These rates are more negative this year than the previous year (a trend that has continued).  These rates also use 1979-2000 as the climatological normal.  There is no reason to expect these rates to change significantly any time soon.  Additional low ice seasons will continue.  The specific value for any given month during any given year is, of course, influenced by local weather conditions.  But it becomes clearer every year that a new normal is being established in the Arctic.  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 10, 2011:

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110910.

Compare this with August 7th’s satellite representation, also centered on the North Pole:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110807.

Compare both of these with December 12th’s satellite representation (note that the AMRS-E instrument failed during early October; replacement data is available at a lower resolution):

Figure 3 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20111212.

There is more ice at this time of year in the Bering Sea and Hudson Sea than there were last year.  There is missing ice north of Scandinavia – this is the result of anomalously warm conditions in that region during the past month or so.

Overall, the health of the remaining ice pack is not healthy, as the following graphs of Arctic ice volume from the end of August and November demonstrate:

Figure 4 – PIOMAS Arctic sea ice volume time series through August 2011.

Figure 5 – PIOMAS Arctic sea ice volume time series through December 2011.

Within the past month, the magnitude of ice volume anomaly grew less severe, but remains in the 2nd standard deviation from the median.  Just like the sea ice extent has a negative trend, the sea ice volume is decreasing by 2900 +/-1000 cubic kilometers per decade.  The volume anomaly spent a substantial amount of time beneath the 2nd st. dev. value this year, just as it did last year.  The declining trend in volume ensures that future years will witness additional low areal extents.

Switching back from volume to area, take a look at September’s and December’s areal extent time series data:

Figure 6 – NSIDC Arctic sea ice extent time series through early September 2011.

Figure 7 – NSIDC Arctic sea ice extent time series through early December 2011.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from September 10th:

Figure 8 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20110910.

Compare that graphic with the same view from December 12th (again, the AMSR-E instrument failed in October and these data are what everybody is currently working with):

Figure 9 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20111212.

Ice loss is easily visible around the continent.  High ice concentrations remain well into the austral spring east of the Antarctic Peninsula (the land mass that “points” to South America).

Here is the Antarctic sea ice extent time series from September:

Figure 10 – NSIDC Antarctic sea ice extent time series through early September 2011.

For comparison, here is the same data series from December:

Figure 11 – NSIDC Antarctic sea ice extent time series through early December 2011.

You can see how recent weather conditions have slowed the rate of ice melt in the past few weeks.  As weather conditions are highly variable from week to week, I expect the rate of  melt to increase again soon: the +/- 2 standard deviation envelope is close to the average, as shown in Figure 11.  Conditions were different in the early austral spring between 2010 and 2011.  They are now much more similar in value.

The biggest reason for the different trends seen in Arctic and Antarctic data?  It’s the so-called ozone hole.  One project I did this semester was a literature review on the mechanisms and projections of ozone loss in the stratosphere.  I will post most of that material on this blog after I make some adjustments.  Put simply, ozone absorbs UV radiation (high energy) and re-radiates that energy as heat into the stratospheric air.  As CFCs and other compounds have introduced halogens to the stratosphere and as UV radiation has released reactive forms of those halogens, ozone loss has occurred.  As ozone concentrations decrease, less heat is re-radiated to the stratosphere.  Colder air has therefore been present over Antarctica than otherwise would be the case.  Greenhouse gases have reinforced this process.  As CFC levels decrease in the future, however, stratospheric and columnar warming should occur.  After a few more decades, global warming will have more influence over Antarctica and we will see how sea- and land-based ice is then affected.

Errata

Here are my State of the Poles posts from August and July.

You can find NSIDC’s December report here.

Cross-posted at SquareState.

State of the Poles – Aug 2011: Arctic Ice Near Record Low; Antarctic Ice Back To Average

The state of global polar sea ice area in early August 2011 continues to fare poorly: well below climatological conditions (1979-2009) persist, as they have for every month so far this year.

Sea ice in the Arctic continues to track significantly below average, between the second worst and worst readings during July (depending on the day) in the modern era.  Weather conditions around Antarctica returned to normal during July, recovering from a temporary stall in freezing that occurred during June.  Global sea ice area therefore tracked well below normal during July, reaching for historical lows reached only three times before now.  During July, global sea ice area hovered near the negative 2 million sq. km. anomaly mark.  To date, this is the longest stretch of time that such a negative anomaly has stayed near 2 million sq. km.

To help put this in context, only three previous times in recent history have seen conditions as bad as they are today: in 2007, 2008 and 2010.  The difference between these previous occurrences and current conditions is profound: they previously occurred around September, when Arctic ice reached its annual minima.   Will a new record low global sea ice area be recorded this year?  Stay tuned.  There is only one more month of melting to go in the Northern Hemisphere, while the Southern Hemisphere’s freezing rate will slow down.

NASA’s Discovery Class Missions: Discovery 12 Pre-Selection Made

I definitely missed this a couple of months ago:

NASA announced three future key missions preselected as part of the Discovery program named GEMS, TiME and Comet Hopper.

The Geophysical Monitoring Station (GEMS) will perform for the first time an in-situ investigation of the interior of Mars.

The Titan Mare Explorer (TiME) [...] proposes to determine the composition and depth of the seas of Titan their variation over time and their relation with meteorology and the geography of their surroundings.

The Comet Hopper (Chopper) mission proposes to study in detail a comet over its full revolution around the sun.  The spacecraft will “hop” on the small comet nucleus and collect data about its surface composition and properties. Taking advantage of the weak gravity of the comet nucleus, it will be able to go back in orbit (a “sortie” as shown in the figure above) and remains around the nucleus to study as well the cometary coma to understand the link between the surface activity and the cometary activity.

All three sound like fascinating missions.  Unfortunately, only one will be selected for funding.

The NASA Discovery program is a low-cost mission ($425 million FY2010) program aimed at developing and supporting a well-defined and narrow-range science mission in the field of planetary exploration.

Mars Science Laboratory Landing Site Decided: Gale Crater

In an update to my post earlier this week, NASA has decided that the Mars Science Laboratory’s target landing site will be Gale Crater.

Gale crater is about 96 miles (154 kilometers) wide and has a mountain at its center that rises higher, from the crater floor up, than Mount Rainer near Seattle. The crater, which is named after Australian astronomer Walter F. Gale, is so large that the U.S. states of Connecticut and Rhode Island could fit inside it, NASA officials said.

Launch is set for November of this year, with touchdown expected in August 2012.

NASA & NOAA: June 2011 Among Top 10 Warmest On Record

According to data released by NASA and NOAA this month, June 2011 ranked among the top 10 warmest Junes on record: NASA recorded the 8th warmest June in its dataset; NOAA recorded the 7th warmest June in its dataset.  The two agencies have slightly different analysis techniques, which actually helps to reinforce the results from each other.

The details:

June’s global average temperatures were 0.50°C above normal (1951-1980), according to NASA.  The warmest regions on Earth are exactly where climate models have been projecting the most warmth to occur for years: high latitudes (think Arctic & Antarctic Circles).  The past three months have a +0.49°C temperature anomaly.  And the latest 12-month period (Jul 2010 – Jun 2011) had a +0.52°C temperature anomaly.  Additionally, the March-April-May period of 2011 tied for the 7th warmest on record.

According to NOAA, June’s global average temperatures were 0.58°C (1.04°F) above the 20th century mean of 15.5°C (59.9°F).  NOAA’s global temperature anomaly map reinforces the message: high latitudes are warming at a faster rate than the mid- or low-latitudes.  The extreme warmth over Siberia is especially worrisome due to the vast methane reserves locked into the tundra and under the seabed near the region.  Methane is a stronger greenhouse gas than carbon dioxide, the leading cause of the warmth we’re now witnessing.

These placements high on the list of recorded temperatures come at a time when the recent strong La Nina is coming to an end (which means anomalously cool Pacific waters return to normal temperatures), and when solar irradiance remains at relatively low levels as the most recent solar cycle continues to ramp up.  Recall that a favorite talking point of Deniers is the sun remains the only important component of climate system drivers.  This has been proven false, as 2010, tied for the warmest year on record with 2005, occurred when solar output was at its most recent minimum.  Humans have become the dominant forcing mechanism – a role that doesn’t look likely to end within the next 50-100 years.

Many future Junes will have the opportunity to pass this year’s values.  That’s because the overwhelming majority of heat that has been absorbed in the climate system has been stored in the world’s oceans:

That heat will eventually be released into the atmosphere, making the surface warmer and warmer year after year, decade after decade.  Right now, the atmosphere is being affected by heat that was absorbed by the ocean 50-100 years ago.  The heat absorbed from 1980-current won’t really impact conditions until 2030-2060.  The heat wave impacting the U.S. this year?  That will likely become commonplace by mid-century.  Think about what kind of extreme weather conditions will occur then.