State of the Poles – Apr. 2011: Arctic Sea Ice Steady; Antarctic Below Average

The state of global polar sea ice area in the middle of April 2011 remains poor: well below climatological conditions (1979-2009) continue to persist.  Sea ice in the Arctic continues to track significantly below average, with the 2nd lowest readings for the month in the modern era.  Antarctic sea ice has rebounded very slowly from its annual minimum extent, hovering near record low extent values during March and only recently improving in comparison to historical lows in early April.  Global sea ice area has therefore remained near historical lows for an extended period of time this year.  While global sea ice area has rebounded from its yearly minimum, the difference between this year and climatological conditions has been stuck below negative 1 million sq. km. for the first 3.5 months this year.   Those conditions mimic the trend seen in early 2006 and 2007.  2006 saw the global area increase to normal conditions later in the year.  2007, in contrast, did not.  That, of course, was the year that Arctic sea ice extent plummeted to its lowest value on record.  Weather conditions in the Arctic the rest of this year will help determine whether 2011 challenges 2007 for that dubious position.

Arctic Ice

According to the National Snow and Ice Data Center, Arctic sea ice extent in March was the 2nd lowest on record.  Averaged over March 2010, Arctic sea ice extent was only 14.56 million sq. km.  Arctic ice in March and into early April didn’t change very much in its extent.  This is definitely typical for March, but less so for April.  In fact, overall conditions have held steady since mid-February.  While those conditions were extremely low compared to climatological conditions in February, they were less anomalous by the middle of April.  Climatologically, the extent starts to really decrease by the beginning of April, so the extent anomaly has sharply decreased in the past month from 1.1 million sq. km. below normal to “only” 574,000 sq. km. below normal now.  Hopefully that translates to the lack of record low extents later this year.

The change in March ice extent has been measured at -2.7% per decade by the NSIDC.  What that means is as of the end of March 2011, the Arctic has only 14.56 million sq. km. of sea ice extent, while as of the end of January1978, the Arctic had 16.49 million sq. km. of sea ice.  That difference is real and it is significant.

Arctic Pictures and Graphs

I’m going to do something a little different this month and compare April’s satellite imagery of the Arctic to February’s to demonstrate the general lack of difference between the two.

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

A couple of areas have some lower concentration of sea ice, but the general picture looks the same as it did over two months ago.  One important factor in April’s conditions is the Arctic Oscillation’s return to more positive values since the beginning of the year.  This has allowed colder air to remain in place over the Arctic region.

As a whole, here is what the Arctic ice extent looks like in time-series form through April 19th:

The NSIDC has included the 2007 time-series line as a useful comparative measure for this year’s extent.  After trailing below 2007 conditions for the first 2 months this year, the unchanging extent since early March has meant 2011′s extent is now above 2007′s.  At the end of the 2011 series, you can see that this year’s melt season might finally be in effect.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from April 19th:

For comparison purposes, here is the similar picture from March 2nd:

Sea ice conditions have obviously increased in the last month, as they should have.  To date, I haven’t seen anything regarding the health of the ice shelves ringing the continent.  The longer there is no news, the better, since those shelves keep the land-based ice on land and not allowing them to escape to the sea.

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations in light gray and the climatological mean in dark gray through April 19th:

Antarctic sea ice extent has remained on the low side of the climatological envelope of conditions.  So far, April has seen more extensive freezing than did March.  As you can see, conditions this year have been worse than conditions in 2010.  Unlike the Arctic, however, a long-term trend has not been as dramatic in the Antarctic.

Errata

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

You can find the NSIDC’s April report here. The page is dynamic, so if you’re reading this after April 2011, that month’s report will show up first. If that’s the case, you can look for any report in their archive on the top pull-down tab on the right-hand side of the page.

State of the Poles – Mar. 2011: Record Low Arctic Sea Ice

The state of global polar sea ice area at the end of February 2011 is troublesome: well below climatological conditions continue to persist (1979-2009).  Sea ice in the Arctic continues to track significantly below average, setting a record minimum for the month in the modern era.  Antarctic sea ice continued to hover near record low extent values during February.  Just as it did during early 2006, global sea ice area has double-dipped during the yearly minimum.  Instead of clearly rebounding from that low, as it usually has in the past 40 years, global sea ice is clearly characterized yet again by new conditions.  As of this writing, the global area is -1.4 million sq. km. below average.

State of the Poles – Feb. 2011

The state of global polar sea ice area one month into 2011 is troublesome: well below climatological conditions continue to persist (1979-2009).  Sea ice in the Arctic continues to track significantly below average.  Meanwhile, Antarctic sea ice has switched from well above average extent in mid-December to challenging record lows for the last days of January.  As a result, global sea ice area continued to rapidly decrease during January.  The trend for January is normal, but the values of extent are abnormal.

In last month’s post, I rhetorically asked whether the yearly absolute minimum global sea ice area would look more like 2005, 2009 and 2010 (~15 million sq. km.) or whether 2011′s minimum would be more like 2006 and 2007 (~14.5 million sq. km.).  Click-thru to the link provided above and you’ll see that 2011 unfortunately already looks more like 2006 and 2007.  With about one month remaining in the Southern Hemisphere’s melt season remaining, and with the freeze season in the Northern Hemisphere winding down, this year’s global minimum may not have been reached yet.  In 2006, 2007 and 2009, extent hovered near 14.5 million sq. km. for about one month.  Regardless of the specific date and the specific absolute minimum extent value, the trend in January’s from 2008 through 2011 look very similar to the trend from 2003 through 2007.  Global sea ice is once again in bad condition at the end of January, 2011.

Arctic Ice

According to the National Snow and Ice Data Center, Arctic sea ice extent set a record low in January.  Averaged over January 2010, Arctic sea ice extent was only 13.55 million sq. km., which was 50,000 sq. km. below the previous record low set in 2006.  Areas like Hudson Bay and the Davis Strait finally froze over in January, nearly 2 months behind normal.  The Labrador Sea remains unfrozen, even at this extremely late date in the Northern Hemispheric winter season.

In January, the ice extent was about 1.1 million sq. km. less every day than the normal value.  This was the first time on record that the extent was so low for so long during the first calendar month of the year.  The extent was >500,000 sq. km. lower than during the same period in 2008-2010. Moreover, the last 2 times a calendar year started out anywhere near this negative was in 2006 and 2007.  In 2007, the all-time record low ice extent was set.  For the record, the extent at the end of January 2011 is ~100,000 sq. km. lower than it was in either 2006 or 2007.  Does that mean that a new record low extent will be set this year?  Not necessarily.  2007 witnessed weather conditions that helped ice flow out of the upper Arctic and into warmer waters, where it melted.  That hadn’t happened prior to 2007 in the satellite era, nor has it happened since.  However, the record low volume of ice that was measured in 2010 could mean that ice area extent is in danger of shrinking to near-record lows again in 2011.

The change in January ice extent has been measured at -3.3% per decade by the NSIDC.  What that means is as of the end of January 2011, the Arctic has only 13.55 million sq. km. of sea ice extent, while as of the end of January1978, the Arctic had 15.5 million sq. km. of sea ice.  That is an enormous and significant difference.

Arctic Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from February 7th centered on the North Pole:

Compare these with January 6th’s satellite representation, centered on the North Pole:

The area highlighted by the white oval in the January picture has finally frozen over – only 2 months later than at any point in recorded history.  The NSIDC has a nice multi-year time-series showing how abnormal this winter’s freezing delay has been.  In the past month, the Sea of Okhotsk (east of Russia, north of Japan) has stated to freeze over.  I feel like a broken record with this, but it is doing so at a much slower pace than is normal.  The Baffin and Newfoundland sea ice also remain well behind normal schedule to freeze.

There are different factors affecting each of these areas.  As I’ve discussed previously, the Arctic Oscillation was in an extremely negative phase for months again this winter.  This allowed cold air that normally remains trapped over the Arctic to pour south and affect eastern North America and Europe.  At the same time, a huge dome of high pressure settled over northeastern Canada, allowing much warmer than normal temperatures to remain in place.  I’m not talking just a little warmer than usual, I’m talking about parts of Canada being an average of 38°F warmer for an entire month – and that month should have been one of the coldest of the year for that region.

It was recently announced that there is a phenomenon underlying all of the various weather patterns and climatic oscillations.  According to a new study, water entering the Arctic Ocean between northeastern Greenland and Svalbard is now warmer than it has been at any time over the past 2,000 years.  To make matters worse, the volume of water entering the Arctic is also greater than it was in the past.  So more water that is warmer is being funneled into the Arctic Ocean, which is resulting in a warmer Arctic from below.  This finding has serious implications for the future state of Arctic sea ice.  Even if abnormal weather patterns and oscillations didn’t set up, ice will have a harder and harder time forming and being maintained from year to year because of the additional heat being forced into the ocean.  That heat will have to dissipate prior to any ice formation, let alone ice thickening.  Like I’ve written before, the Arctic has entered into a new climate regime.  It might take a little longer for the effects of that to cascade through the climate system to places where people live.  But once it does, it will be too late to prevent the worst of further effects from continuing to cascade.

Here is the time series graph of Arctic sea ice extent with the +/- 2 standard deviations as a light-gray envelope around the climatological average through February 6th:

You can see how truly poor the Arctic sea ice conditions are with this graph.  The 2010-2011 line shows us that conditions are the worst for the date on record since the middle of December, beating out 2006-2007 every day.  Arctic sea ice continues to track far, far below climatological norms.  The up-shot from the previous paragraph is this: the conditions we’re seeing for the first time this winter are likely to be the new normal.  That thick gray line and the light-gray envelope will be shifted downward.

Antarctic Pictures and Graphs

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

For comparison purposes, here is the similar picture from January 6th:

The sea ice off western Antarctica has fully melted.  The fields adjacent to the coast west and east of the Antarctic peninsula remain in good shape, largely thanks to cooler than normal surface temperatures and sea surface temperatures.  This is an example of a weather phenomenon helping to keep sea ice intact rather than destroying it.

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations in light gray and the climatological mean in dark gray through the 6th:

It’s pretty obvious to see what happened during January: sea ice extent was whittled down at a much faster rate than normal.  It started out slightly above average and ended the month near the bottom of the 2 standard deviation envelope.  While conditions aren’t as dire as they are in the Arctic, Antarctic sea ice melted very quickly this year, especially considering the extent was well above the 2 standard deviation envelope back in mid-November.  It is at this point in the year that ice shelves typically start to break off.  Will 2011 have another big ice shelf break-up news story?  Stay tuned.

Errata

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

You can find the NSIDC’s February report here. The page is dynamic, so if you’re reading this after February 2011, that month’s report will show up first. If that’s the case, you can look for any report in their archive on the top pull-down tab on the right-hand side of the page.

State of the Poles – 1/6/2011

The state of global polar sea ice area at the beginning of 2011 continues the trend present throughout most of 2010: well below climatological conditions (1979-2009).  Sea ice in the Arctic continues to track far below average while Antarctic sea ice has tracked closer to average from above average the past couple of months.  Overall, the rate at which Arctic sea ice is refreezing and Antarctic ice is melting is not out of the ordinary.  The locations where freezing and melting is occurring is once again news this month.  Global sea ice is rapidly decreasing, as is normal for this time of year due to Antarctic environmental conditions.  The value of global sea ice area has already fallen below the average level of 16 million sq. km.  The yearly absolute minimum should occur within the next month or so, at which time we’ll be able to determine whether 2011′s minimum is more like 2005, 2009 and 2010 (~15 million sq. km.) or whether 2011′s minimum is more like 2006 and 2007 (~14.5 million sq. km.).

State of the Poles – 12/5/10

The state of global polar sea ice area at the beginning of December 2010 remains well below climatological conditions (1979-2008).  Sea ice in the Arctic continues to track far below average while Antarctic sea ice stayed slightly above average.  Overall, the rate at which Arctic sea ice is refreezing and Antarctic ice is melting is not out of the ordinary.  The locations where freezing and melting is occurring is news this month.  Global sea ice is rapidly decreasing, as is normal for this time of year due to Antarctic environmental conditions.

State of the Poles – 11/2/10

The state of global polar sea ice at the beginning of November 2010 is once again poor compared to climatological conditions (1979-2008). The Arctic sea ice extent remains well below average for this time of year.  The Antarctic sea ice extent is above average, but not nearly so much as the Arctic sea ice is below average, which is why the global sea ice extent continues to track below average also.  Global sea ice area has made a nice recovery since the mid-year low of ~17.5 million sq.km.  Some portions of the Arctic Sea weren’t as warm as they were after the 2007 or 2008 melt seasons, which has allowed Arctic Sea ice to refreeze in those areas quite rapidly.  One of the plots below will demonstrate nicely which areas were cooler and which were warmer.  The prime melt season for Antarctic sea ice is about to begin.  The global sea ice area will start to plummet as the southern sea ice melts before bottoming out in a few months’ time.