SquareState - Arctic ice

State of the Poles - June 2012: Arctic Ice Extent Below Normal; Antarctic Ice Near Clim. Norm

WeatherDem — Thu, 14 Jun 2012 16:26:00 GMT

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 April 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.

Cross-posted at WeatherDem - the blog.

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

WeatherDem — Sun, 22 Jan 2012 18:04:34 GMT

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 graphsof 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.

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

WeatherDem — Wed, 14 Dec 2011 17:36:46 GMT

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.

Polar Bear Cubs Die More Often With Less Arctic Ice

WeatherDem — Tue, 19 Jul 2011 22:14:26 GMT

As Arctic ice thins and melts more and more every year, polar bear cub mortality is rising. Compared to cubs that don't have to swim as far to reach sea ice, which had a 19% mortality rate, cubs that are being forced to swim for days without reaching ice had a 45% mortality rate in a recent study.

With less body fat, the cubs can't maintain their internal body heat as long as adults and they aren't as buoyant in the water. The cubs either drown because they can't keep their noses above water or they succumb to the colder water.

I will point out that this is only one species. There are many other species we didn't even know existed that are under similar pressures from our greenhouse pollution. On top of that, there are yet more species whose fate are being sealed every day we don't reduce that pollution.

The Anthropocene is underway. What happens in this Epoch is up to us.

New Arctic Ice Assessment: Faster Melt = Faster Sea Level Rise

WeatherDem — Tue, 03 May 2011 18:49:28 GMT

Most of the projections in the science portion of the IPCC's 2007 4th Assessment Report have been shown many times since its issuance to be too conservative. Temperatures have risen faster; ice (sea- and land-based) has melted faster; ocean acidification and warming has happened faster, the number of extreme weather events has increased faster, etc.

I've written before about most of these. I will take this space to write once again about polar ice melting faster than projected (according to observations) and the impact that will have on global coastlines.

According to the executive summary of a new assessment of Arctic climate, the international Arctic Monitoring and Assessment Program (AMAP) reports that Arctic temperatures in the past six years were higher than at any time since measurements began in 1880. Moreover, feedback mechanisms have already started.
What this means is the arctic sea ice area and global sea level projections made by the IPCC just 4 years ago underestimate this year's conditions, which means they also very likely underestimate future conditions too. In an updated projection that has deep significance for billions of people worldwide:

The melting of Arctic glaciers and ice caps, including Greenland's massive ice sheet, are projected to help raise global sea levels by 35 to 63 inches (90-160 centimeters) by 2100, AMAP said, though it noted that the estimate was highly uncertain.
That's up from a 2007 projection of 7 to 23 inches (19-59 centimeters) by the U.N. panel, which didn't consider the dynamics of ice caps in the Arctic and Antarctica.

Is the difference between one-half to 2 feet and 3 feet to 5 feet significant? Only those of us who are sane seem to think so. This is but one effect of oil corporations continuing to post record profits quarter after quarter, year after year. How much infrastructure exists near 5ft above sea level worldwide? How much is that infrastructure worth? How much cropland exists at those low altitudes? How many miles of ruined cropland from rising seas only will occur before widespread food shortages occur? How much is our lifestyles worth; how much do they really cost?

AMAP scientists will discuss their findings in Copenhagen, Denmark starting tomorrow.

Cross-posted at WeatherDem - the blog..

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

WeatherDem — Wed, 09 Mar 2011 05:02:17 GMT

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.
Arctic Ice

According to the National Snow and Ice Data Center, Arctic sea ice extent set a record low again in February. Averaged over February 2010, Arctic sea ice extent was only 14.36 million sq. km., tying the record low set in 2005. The NSIDC notes, "Every year since 2004 has had a mean February extent below 15 million square kilometers". That's a new state for the Arctic; a state which is looking increasingly permanent. Large areas of the Okhotsk Sea, Greenland Sea, Newfoundland Sea, Baffin Bay and St. Lawrence River remain unfrozen, which is decidedly abnormal for the end of February.

In February, daily Arctic ice extent values remained about 1.1 million sq. km. less than the normal value. This continued the trend that I noted in my post about January conditions. This is the first time on record that the extent has been so low for the first two calendar months 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. By this time in 2006 and 2007, the ice extent was ~200,000 sq. km. higher than it is during 2011. 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. I will say this, however: the longer the extent remains so abnormally low, the less extreme weather conditions will have to be during this upcoming summer to generate record low conditions again. A lot of young, thin ice currently resides in the Arctic. It won't take as much as it did in the past to melt the ice this year.

The change in February ice extent has been measured at -3.0% per decade by the NSIDC. What that means is as of the end of February 2011, the Arctic has only 14.36 million sq. km. of sea ice extent, while as of the end of January1978, the Arctic had 16.4 million sq. km. of sea ice. That difference is real and it is significant.

Arctic Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from March 2nd centered on Hudson Bay:

And here is a satellite representation of Arctic sea ice conditions from March 2nd centered on the Bering Sea:

Compare these with February 7th's satellite representation, centered on the North Pole:

It's easy to see where shorter-term climatic oscillations and this season's weather conditions have worked to prevent sea ice from forming on this month's satellite representations. That being said, the Arctic Oscillation has switched from being extremely negative to positive in the past few weeks. What this means is cold air is being bottled up near the Arctic Circle instead of rushing south over the eastern U.S. and Europe. This could allow for a late season freeze-up of ice around the periphery of the current ice pack. Next month's post will take another look at those conditions.

As a whole, here is what the Arctic ice extent looks like in time-series form through March 2nd:

The NSIDC has included the 2006-2007 time-series line as a useful comparative measure for this year's extent. 2007 witnessed the smallest areal extent covered by Arctic sea ice in the modern era. It obviously remains unknown at this time whether this September's extent will challenge 2007's for the record low. But I'll mention this again: a lot of the ice in those satellite representations are only a few months old. They face warmer conditions in the ocean and in the lower atmosphere than any Arctic sea ice has in tens of thousands of years. As each year passes, that becomes more evident as these time-series lines track far, far below average conditions of just a few decades ago.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from March 2nd:

For comparison purposes, here is the similar picture from February 7th:

Sea ice conditions haven't changed that much in the past month. I haven't seen anything yet regarding 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 it 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 March 2nd:

After a torrid pace of ice melting in January, little ice was left to melt in February. That combined with continued cooler than normal conditions on the east side of the Antarctic Peninsula and off the coast of West Antarctica meant melting drastically slowed down through February. In fact, during the last week of February, conditions have shifted and now ice is refreezing. After hugging the bottom of the 2 standard deviation envelope for over a month, Antarctic sea ice extent is slowly edging back toward the mean extent value.

Errata

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

You can find the NSIDC's March report here. The page is dynamic, so if you're reading this after March 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.

Cross-posted at WeatherDem - the blog.

State of the Poles - 1/6/2011

WeatherDem — Thu, 13 Jan 2011 22:55:28 GMT

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.).
Arctic Ice

The rate of freezing of Arctic sea ice continued to slow down from November to December. The ice extent averaged over December 2010 was the lowest on record: 12 million sq. km., which was 270,000 sq. km. below the previous record low set in 2006. The presence of relatively warm pockets of water in the region, combined with local weather patterns present during November, helped push the extent to a record low.

In December, the ice extent was about 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 last calendar month of the year. The extent was ~200,000 sq. km. lower than during the same period in 2009 and ~500,000 sq. km lower than during the same period in 2008. Recall that the ice extent was anomalously low for the longest period of time (5 months) and the 2nd lowest overall extent on record (behind 2007) in 2010. The last time the ice extent was at zero anomaly was way back in December 2004. The last time the ice extent spent more than a day or two above the zero anomaly line was back in early 2003. The change in December ice extent has been measured at -3.5% per decade by the NSIDC. It should be noted that for the first 16 years of that record, the extent didn't have a significant positive or negative trend. It is only since the early 1990s that a noticeable trend has developed. I've written many times now that the Arctic appears to have entered a new regime. These kinds of anomalous conditions characterize that new regime. I don't definitively know what a -1.181 million sq. km. ice extent in early January means for September ice extent. I am not confident that it means September ice conditions will return to normal.

More important to polar climate processes than areal extent, however, is the volume of ice. Arctic ice volume has been decreasing for decades, but has worsened considerably in the past 5 years. After setting a record low earlier this year, ice volume rebounded somewhat so that it was back within the ~~2 standard deviation envelope. In December, the volume looks to have stabilized near~~ 8 million cubic km. We should all hope that the volume stays at or near this level instead of plummeting to new record lows as it did in 2010.

Arctic Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from January 6th centered on the North Pole:

Compare these with December 5th's satellite representation, centered on the Hudson Bay:

The white oval in the January map highlights an area where sea ice remains missing weeks to months after it normally forms. I wrote last month that the Hudson Bay was normally half covered with ice by the end of November. It should ice over the its entire surface by now. But you can see that the Bay still doesn't have ice cover near its eastern shoreline. Why is this? Near-surface air temperatures in this region were 4-8F warmer than normal in December. It has been warm enough to stave off ice formation for weeks to months later than usual. Also in the white oval is the west coast of Greenland and Baffin Island. Want some really frightening news? These regions witnessed near-surface air temperatures that were 8-12F warmer than normal. As a result, these regions remain ice-free in the middle of winter. That's not a good sign. Neither are the warmer sea surface temperatures in the North Atlantic and off the west coast of Greenland.

One cause of these conditions is the Arctic Oscillation, which has allowed cold Arctic air to move much further south than normal, hence the rough winters that the eastern U.S. and Europe are facing. The Arctic Oscillation Index was slightly positive in the beginning of November, but transitioned to negative in the second half of November before returning to near zero by the beginning of December and finally turning very negative again in mid-December. This is the third winter in a row that the AO Index was extremely negative. The NSIDC notes that

Starting in the 1970s, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia.

So the most recent winters in some areas are indeed out of the "normal" realm that many people grew up experiencing.

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 January 6th:

The red ovals highlight important chances in Arctic sea ice extent. Ice extent actually declined during those two periods - the first in the middle of December and another one in the first week of January. This has occurred in the past, but it is very rare for the ice extent to shrink during the middle of the winter. After declining in December, the Arctic sea ice extent was the lowest on record for those calendar days. As you can see from the above time series, the extent continues to set calendar-day record lows.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from January 6th:

For comparison purposes, here is the similar picture from December 5th:

I pointed out the areas highlighted by white ovals in the December picture as "ice-free ocean close to a continental land mass surrounded by solid sea ice". Sea ice near those areas continued to melt from the continent out, but ocean currents and weather patterns also melted neighboring ice from the sea in. Above-average near-surface temperatures near the areas in the white ovals continued through December, helping to melt the ice in this fashion. You can see that the sea ice off Eastern Antarctica (near the bottom white oval) almost completely melted away during December. That is a fairly common occurrence. Sea ice off Western Antarctica has been able to stay together a little while longer. Massive fields of sea ice in rather poor condition can still be found in this area (blue colors indicating low sea ice concentration). Perhaps of more interest is the sea ice that is still in good condition off the east coast of the Antarctic peninsula (the rather skinny piece of land sticking out into the ocean) and the sea ice hugging the coast to the west of the Antarctic peninsula. These areas experienced cooler than normal conditions (surface temperature) during December. If local temperatures continue to stay below normal the rest of the austral summer, the sea ice could hang around for another season.

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:

Antarctic sea ice in late 2010 declined from its above-average extent witnessed during October and November. The extent is now near the long-term average value of 5-6 million sq. km. The extent heading into 2011 is slightly lower than the extent heading into 2010. The NSIDC had this to say about Antarctic conditions:

The high ice extent around Antarctica appears to relate to a persistently positive phase of the Southern Annular Mode-an Antarctic counterpart to the Arctic Oscillation-and to the mild La Niña conditions in the Pacific.

For the time being, at least, seasonal forcings are the primary driver of Antarctic sea ice. Conditions in the Southern Hemisphere certainly are not as anomalous as conditions in the Northern Hemisphere.

Errata

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

You can find the NSIDC's January report here. The page is dynamic, so if you're reading this after January 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.

Cross-posted at WeatherDem - the blog.

State of the Poles - 12/5/10

WeatherDem — Tue, 07 Dec 2010 17:30:04 GMT

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.

Arctic Ice The rate of freezing of Arctic sea ice slowed in November from October. Ice growth was actually slower than the climatological normal rate. It was so slow that Arctic sea ice extent averaged over November 2010 was the second-lowest November ice extent recorded - a mere 50,000 square kilometers above the previous record low of 9.84 million square kilometers set in 2006. The presence of relatively warm pockets of water in the region, combined with local weather patterns, helped keep the extent this low. A time series graph of ice extent anomalies maintained by the University of Illinois at Urbana-Champaign’s Polar Research Group shows that ice extent moved past the \-1 million sq. km. anomaly line for a short time during November. It is currently hovering near \-1.1 million sq. km. The duration of this low anomaly has only been recorded once before, in the record low 2007 year. While still negative, the anomalies in 2008 and 2009 were not as severe as this year’s. The change in November ice extent has been measured at -4.7% per decade by the NSIDC. It should be noted that for the first 16 years of that record, the extent didn't have a significant positive or negative trend. It is only since the early 1990s that a noticeable trend has developed.

More important to polar climate processes than areal extent, however, is the volume of ice. Arctic ice volume has been decreasing for decades, but has worsened considerably in the past 5 years. After reaching a record low earlier this year, volume has recently risen back above -9000 cubic kilometers. Older ice tends to be thicker ice. Unfortunately, the age of ice in the Arctic has shifted significantly in recent years. Back in the 1980s and early 1990s, between 50% and 60% of the September Arctic ice was older than 2 years. That situation shifted in the 1990s and early 2000s when >2 year-old ice decreased to ~40% of all ice in the Arctic. 2008 was a devastating year for old Arctic ice, declining to 30% of all Arctic ice. Reflecting the new regime, old ice in 2009 declined to 20% of all ages and declined even further in 2010 to 10%.

Arctic Pictures and Graphs

I will show slightly different versions of Arctic sea ice as seen from satellites in order to highlight the warm sectors I alluded to above. Here is a satellite representation of Arctic sea ice conditions from December 5th centered on the Bering Sea:

Here is a satellite representation of Arctic sea ice conditions from December 5th centered on Hudson Bay:

Compare these with November 2nd's satellite representation, centered on the North Pole:

The white ovals highlight areas where sea ice is only beginning to form in early December, weeks after the time when this normally happens. Near-surface air temperatures near Siberia and Alaska were 5-9F warmer than normal in November. Most of the sea ice in the Bering Sea formed only within the past 7 days. Instead of half of Hudson Bay being covered by sea ice at the end of November, only 17% was covered by November 30th, 2010. Most of that 17% appeared in the last few days of the month. Normally, sea ice is found much further south along the west coast of Greenland. Even while a strong La Nina persists in the equatorial Pacific, sea surface temperatures in the North Atlantic are much higher than average.

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 December 4th:

Remember, only 2006 saw a lower extent through November.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from December 5th:

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

The areas highlighted by white ovals in the December picture show something rather odd: ice-free ocean close to a continental land mass surrounded by solid sea ice. You can actually pick out the birth of these regions in the November picture. The cause of these ice-free areas is above-average near-surface air temperatures, which have been present near these regions throughout most of 2010.

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 yesterday:

Antarctic sea ice in late 2010 is only slightly above the climatological norm. It is also higher than recent years' extent for the same calendar date. The only useful conclusion to draw from those observations is the Antarctic still isnt' responding to global warming forcing in the same way the Arctic is. Some of this has to do with the relative magnitude of warming over both poles, which isn’t the same. Another factor to consider is the presence of the ozone hole over Antarctica, which has allowed stratospheric temperatures over Antarctica to warm relative to climatological norms. This has had the effect of increasing the strength of the circumpolar vortex, which has kept cold air nearer to the South Pole and maintained the integrity of land and ice sheets.

Errata

Here are my State of the Poles posts from November and October.

You can find the NSIDC’s December report here. The page is dynamic, so if you’re reading this after December 2010, 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.

Cross-posted at WeatherDem - the blog.

State of the Poles - 9/7/10

WeatherDem — Fri, 10 Sep 2010 00:11:10 GMT

The state of global polar sea ice at the beginning of September 2010 is once again very poor compared to climatological conditions (1979-2008). The Arctic ice extent is far, far below average for this time of year. The Antarctic sea ice extent is above average, but not nearly so much as was the case at the beginning of August. Unfortunately, global sea ice extent has fallen to ~18 million sq. km., something that has happened in only 2 previous Septembers: in 2007 and 2008. The Northwest Passage and the Northern Sea Route are largely free of ice, allowing the Arctic Ocean to potentially be circumnavigated.

Each month and each year that goes by provides additional proof that the Arctic has entered into a new state; a different state than has existed for 1,000 years or more. Monthly and yearly weather conditions have varied considerably over the past few years, as one would expect, but the end result has been nearly the same regardless of any specific condition: Arctic sea ice is declining year-over-year. It is declining at a rate that exceeds scientific estimates from just a few years ago. Climate change deniers keep prattling on about increasing sea ice, in direct contradiction to the physical realities before them. I think most of the areas that have sea ice this September will not have sea ice by 2020. Specific weather or geologic events might delay the year that occurs slightly, but I don't think it will take too much longer to witness an Arctic Ocean that is essentially ice-free.
Arctic Ice

In August, rapid melting of sea ice that is less than one year old continued. Additionally, weather conditions developed during August that assaulted multi-year ice. This ice is thicker and takes more energy to melt. Just like the past few years, conditions have been sufficient to melt an increasing volume of ice that is longer lived. If the Arctic's recent past is any clue, it will become easier in upcoming years to keep melting ice that forms in the previous winter, thus reducing the availability of longer-lived, more stable sea ice.

September 3rd represented a milestone in poor Arctic sea ice conditions. On Sep. 3rd, Arctic sea ice extent fell below the seasonal minimum for 2009 to claim third lowest value on record, behind 2007 (the record lowest) and 2008. In the days since, ice extent has continued to fall and is close to challenging 2008 for 2nd lowest, a dubious honor to achieve. About the only good news is that the rate of melting has been slowing down in recent weeks and the seasonal minimum for 2010 should be reached in the next couple of weeks. The Arctic Ocean does have quite a bit of energy in the form of heat to release into the atmosphere before sea ice can form again. The relatively large expanse of dark blue ocean has had a large opportunity to absorb solar radiation again this year.

To give you a better idea of how Arctic ice volume has changed over the satellite record, click the following link, which shows that ice volume has been decreasing for decades, but has really worsened in the past 5 years. The graph shows how a particular day's ice volume compares to the climatological record, which in this case extends from 1979-2009. This time series is extremely disturbing. It is one of the biggest pieces of evidence to support my postulation that the Arctic will be essentially ice free within a decade. A system like the Arctic Ocean can only take so much forcing year after year before its characteristics fundamentally change.

Antarctic Ice

The state of Antarctic sea ice at the end of August 2010 was actually close to its state at the end of July, though the intervening daily changes were pretty large. In the middle of August, for instance, Antarctic sea ice extent jumped way up to register a day-of-year maximum in the satellite record. This situation caused a denier's heart to flutter, mostly because they don't understand the difference between weather and climate. The explanation for the increase that excited this denier, and the almost immediate subsequent decrease in extent was actually due to local weather conditions as a result of the Antarctic Oscillation. The denier didn't care one whit what the scientific cause was, of course, nor do they truly care about transparency and honesty. They only cared that for one brief moment in time, some data seemed to confirm their pre-conceived, biased view on climate change, which is based solely on extremists' talking points.

Another commenter tried to lecture me on talking about the viability of Antarctic ice because I hadn't personally measured its thickness. I suppose the years of measured Antarctic ice can't provide anybody the opportunity to discuss things like typical ice thickness and its tendency to nearly completely melt every austral summer. Just like the Arctic, if the Antarctic sea ice were thicker, it wouldn't melt every year. Since the vast majority of it melts on a yearly basis, it can't be that thick. Little things like basic physical laws govern this behavior, not my attitude or viewpoint or anything else as ridiculous.

#####

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

You can find the NSIDC's September report here. The page is dynamic, so if you're reading this after September 2010, that month's report will show up first. If that's the case, you can look for whatever report you're looking for on the top pull-down tab on the right-hand side of the page.

Arctic Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from yesterday:

Compare that with the similar picture from early August:

As you can see, another dramatic change in sea ice conditions occurred between early August and early September. Large regions of 90%+ sea ice concentration has given way to open water (which absorbs heat, instead of reflecting it) and areas of 40%-80% sea ice with melt water on top of it continue to be present, which does much of the same thing. The seasonal minimum ice extent will look something like the top graphic, considering there isn't much more time before it occurs. By the time my next Pole post is written, some areas will look a little better than the September version. The August graphic is actually useful in another way. It shows conditions that were just slightly worse than the average conditions observed over the past 30-plus years. The seasonal minimum used to be a little larger in extent than what that bottom graphic displays. So you can pretty easily see how the Arctic has changed: this year's seasonal minimum will be somewhat less than what is shown in the September graphic and the climatological minimum is somewhat more than what is shown in the August graphic.

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 yesterday. This month's version, thanks to the NSIDC report, also shows conditions of recent years:

The 2010 extent is challenging record lows and is clearly very far below the 2nd standard deviation area. I can't emphasize that second point enough, it seems. The difference between the Arctic's deviation from past extremes is much larger than the Antarctic's deviation from past medians. That is, the distance between the Arctic's 2010 line (in blue) and the bottom of the light gray shading is significantly larger than the Antarctic's 2010 line and the solid gray line (the Antarctic's time series can be found further down in this post). What this time series graph tells us is the past handful of years have witnessed a very different kind of sea ice behavior in the Arctic compared to the recent past. This alternate time series shows that the Arctic's sea ice area is running a 1.6 million sq. km. deficit compared to climatological conditions. Today's extent is sitting at just a hair over 3 million sq. km., when the average is 4.7 million sq. km. If this year's value dips below 3 million sq. km., it would only do so for the 2nd time in recorded history; the first was the stunning year of 2007. This anomaly time series graph shows how different 2010 has been from recent years: ice area has spent a considerable amount of time at around (-)1.5 million sq. km., much longer than any year so far. 2007 saw a larger deficit, to be sure, and perhaps it spent more cumulative time at or below (-)1.5 million sq. km., but 2010's anomaly looks very different from 2009's or 2008's, when the area anomaly hovered closer to (-)0.25 million sq. km. earlier in the calendar year.

The alternative Arctic sea ice extent time series that I recently found shows conditions since 2002, with different years represented by different colored curves. It provides additional context for comparing current conditions against those from the past. One of the striking things that came through was the record-setting extent of ice in early April 2010 (red curve; the largest areal extent occurring at the latest calendar date on record) shifting to the record-setting low extent of ice in June 2010 and maintaining a 2nd lowest extent on record throughout July 2010. We only have another 6-8 weeks to find out where 2010's final areal extent will land with respect to other recent years.

Arctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from yesterday:

For comparison purposes, here is the similar picture from August:

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 yesterday:

There are some interesting things to note about these graphs. First, the Antarctic sea ice extent has undergone a very large increase since mid-March. Typically, it does so anyway, as seen by the mean value in dark gray in the time series graph. But the extent has stayed above normal, indeed at or above the +2 standard deviation throughout the austral winter season. As I wrote above, this condition was largely due to the uncharacteristically strong Antarctic Oscillation, which has kept the oceans around Antarctica dark and stormy, allowing for ice to build up horizontally away from the continent. You can pretty easily tell when that strong Antarctic Oscillation started winding down in the time series graph: around the 2nd week of August. After that, sea ice extent actually decreased somewhat and then has bounced around the same value. It is worth noting that the values measured after the Oscillation started returning to a less extreme state remain higher than the climatological mean. Furthermore, they have remained above the +2 standard deviation envelope also. That said, the difference between the value measured in the 2nd week of August that was clearly above the deviation envelope isn't as large or as long-lived as the difference measured in the Arctic.

The Arctic sea ice extent has been very significantly below the average value for a number of years in a row now. The Antarctic sea ice extent has bounced around the average value during that same time period. It hasn't spent anywhere near the same amount of time above or below the mean that the Arctic's extent has spent below its mean. It hasn't been anywhere near as far away from the mean, especially on a regular basis, as the Arctic's extent has. The year-after-year Arctic sea ice loss that has been recorded during the past few years (regardless of month of year, which means the signal is very strong indeed) is a result of the warming trend seen in the Arctic over the past 30 years or so. That warmth has accumulated over the Arctic more so than over the Antarctic to date. Without changes to global greenhouse pollution rates, the Antarctic is only biding its time until its land-based ice sheet undergoes its own melt scenario, which will have real-world consequences that its sea ice sheet melt doesn't.

Cross-posted at WeatherDem - the blog.

State of the Poles - 8/7/10

WeatherDem — Sun, 08 Aug 2010 17:48:03 GMT

The state of global polar sea ice in July 2010 is somewhat poor compared to climatological conditions (1979-2008). The Arctic ice extent once again finds itself far below average extent for this time of year. In contrast, the Antarctic sea ice extent remains significantly above average conditions. Given those two quite different stories, the fact that global sea ice extent has once again fallen below 19 million sq. km., just as it has the past five consecutive years and eight out of the past nine, speaks to the dangerously poor condition of Arctic sea ice.

A quick aside: it's not just the regions north of 60 that are experiencing ridiculous warmth this year. As I'll detail further in my upcoming post on the NASA & NOAA global temperature datasets, numerous areas across the Northern Hemisphere have experienced record breaking heat this summer. Washington D.C. has witnessed its warmest June-July on record. Moscow has experienced its warmest temperatures on record, while massive wildfires rage across the Russian countryside - burning both forests and peat bogs (all of which releases even more CO2 into the atmosphere). All-time record temperatures for country after country has fallen this year - further speaking to the dead seriousness of climate change's effects now beginning to take hold.
Arctic Ice

In July, rapid melting of sea ice that is less than one year old continued. This ice is the thinnest and thus the most susceptible to warmer conditions. At this stage in the season however, the susceptibility of one-year old and older ice to melt is becoming clear. ~2 million sq. km. of Arctic sea ice melted in July 2010, which wasn't the fastest July melt ever, but still was significant given the overall numbers. ~7 million sq. km. of sea ice remain in the Arctic today.

When you read or hear that most of the warming already experienced by the Earth has happened near the poles and places with high altitude, this is merely one effect that is truly visible on relatively short time frames. Rapid growth and decay of ice on a yearly basis can and will occur. More importantly than areal extent is ice volume, which has dramatically decreased in recent years. As this recently developed time series shows, ice volume has been decreasing for decades, but has really worsened in the past 5 years. It is only recently that enough volume has finally melted that this climate change impact has become obvious in the areal extent of sea ice (by setting record low areal extent).

Antarctic Ice

The state of Antarctic sea ice at the end of July 2010 was as large as it was at the end of June - remaining at much more than climatological normal conditions throughout the month. I haven't read anything definitive as to the reason for this, but given how much Antarctic ice melts and grows each year and taking into consideration the evidence of rapidly decaying and growing Arctic ice, it makes sense that Antarctic sea ice isn't very thick. Nearly all of it melts every year. It further appears as though the rate of growth or decline simply shifts annually with given weather conditions, as we expect.

#####

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

Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from yesterday:

Compare that with the similar picture from early July:

That's a pretty stunning change in the course of one month. Large regions of 90%+ sea ice concentration has given way to open water (which absorbs heat, instead of reflecting it) and areas of 40%-80% sea ice with melt water on top of it, which does much of the same thing.

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 yesterday:

You can see in the graph that 2010 extent is hovering near record lows and is clearly far below the 2nd standard deviation area. Furthermore, the extent of 2010 has already fallen below the 1979-2000 mean value. Keep in mind when viewing this time series that there is still over one month of potential melt facing the Arctic. Even if the extent decreases at climatological normal rates, 2010 would rank among the worst on record.

In a larger context, how do recent years' ice extent compare to IPCC predictions? Well, this is one phenomenon among a growing list that is showing worse conditions than the too-careful IPCC folks were willing to give credence to. What do I mean? Look at Figure 13 of this document (4MB pdf) showing the average and range of September minimum Arctic sea ice extent as projected by models considered by the IPCC. The time series starts in 1900 and runs through 2100. The 20th century projections performed pretty well compared to the observed sea ice extent (denoted by the red line). Sea ice remains as a phenomenon that isn't well understood, so this decent performance is fairly impressive.

But look what happened in the early 21st century (i.e. the last 9 years). The observations fell off to a level that the IPCC models didn't project would be reached until the middle of the century. In other words, the most recent IPCC projections were 40 years too late in projecting the recent record low extents observed in the Arctic!! Note that the models project a gradual decrease in extent down to about 2 million sq. km. by the year 2100. Some glaciologists and climatologists that engage in field activities in the Arctic are now pushing the date at which the minimum plummets below 2 million sq. km., even down to zero-effective extent, all the way back to the next 3-10 years! So not only will most of us witness an ice-free Arctic within our lifetimes (as the IPCC projected 3 years ago), most of use will likely witness an ice-free Arctic within the decade.

You can find the NSIDC's August report here. The page is dynamic, so if you're reading this after August 2010, that month's report will show up first. If that's the case, you can look for the August report on the top pull-down tab on the right-hand side of the page.

Here is a satellite representation of Antarctic sea ice conditions from yesterday:

For comparison purposes, here is the similar picture from July:

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations through yesterday:

Contrary to Arctic sea ice conditions, the Antarctic sea ice extent has undergone a very large increase since mid-March. As the time-series above demonstrates, today's extent is very unusual (outside the +/- 2 standard deviation range). As I wrote above, however, the rather unusual current Antarctic extent isn't as unusual as the current Arctic conditions. The year-after-year Arctic sea ice loss that has been recorded during the past few years is a result of the warming trend seen in the Arctic over the past 30 years or so. That warmth has accumulated over the Arctic more so than over the Antarctic to date. Without changes to global greenhouse pollution rates, the Antarctic is only biding time until its land-based ice sheet undergoes its own melt scenario.

Cross-posted at WeatherDem - the blog.

State of the Poles - 7/7/10

WeatherDem — Wed, 07 Jul 2010 20:06:45 GMT

The state of global polar sea ice in July 2010 is fairly good compared to climatological conditions (1979-2008). The Antarctic sea ice extent is rebounding very nicely from its Southern Hemispheric fall minimum. It has passed the climatological median as well as the +2 standard deviation (meaning there is much more ice than is normal for this time of year). Heat isn't simply making the east coast swelter this week. At the same time that dozens of American cities set daily record highs, the Arctic sea ice extent continues to set calendar-day record lows. Conditions there are the worst on record for July, substantially beating out years such as 2006 and 2007 for record low extent throughout most of June, as this time series shows.
Arctic Ice

The big change since last month has been the continuation of very rapid melting of ice that is less than one year old. This ice is the thinnest and thus the most susceptible to warmer conditions. In fact, as of the beginning of July 2010, the areal ice extent reached a modern-day record low of ~9 million sq. km., which is 2 million sq. km. below the climatological average! Unfortunately, ~2 million sq. km. of Arctic sea ice melted in June 2010. When you read or hear that most of the warming already experienced by the Earth has happened near the poles, this is merely one effect. Rapid growth and decay of ice on a yearly basis can and will occur. More importantly than areal extent is ice volume, which has dramatically decreased in recent years. As this recently developed time series shows, ice volume has been decreasing for decades, but has really worsened in the past 5 years. It is only recently that enough volume has finally melted that this climate change impact has become obvious in the areal extent of sea ice.

Antarctic Ice

The state of Antarctic sea ice in July 2010 was much better than it was during June 2010 - exceeding the average extent relative to climatological norms by an increasing margin throughout the last month. The areal extent shifted from normal to significantly more than normal during this time. The extent at the middle of July 2010 was larger than at the middle of July 2009. I haven't read anything definitive as to the reason, but given how much Antarctic ice melts and grows each year and taking into consideration the evidence of rapidly decaying and growing Arctic ice, it makes sense that Antarctic sea ice isn't very thick. Nearly all of it melts every year. It appears as though the rate of growth or decline simply shifts annually with given weather conditions.

#####

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

Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from a couple days ago (no image for yesterday is yet available):

For comparison purposes, here is the similar picture from June (just a couple of weeks ago):

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 yesterday:

I was recently made aware of a slightly different Arctic sea ice extent time series - one that shows conditions since 2002, with different years represented by different colored curves. I have found that it provides additional context for comparing current conditions against the past. One of the striking things that came through was the record-setting extent of ice in early April 2010 (red curve; the largest extent occurring at the latest calendar date) shifting to the record-setting extent of ice in June 2010. While the rapid melting observed so far this year is significant, it doesn't really indicate one way or the other what conditions this fall will be. 2007 (dark green curve) and 2008 (light green curve) witnessed very low extents. Will weather and ice conditions be conducive to repeat that sad state this September? We'll have to wait and see.

In a larger context, how do recent years' ice extent compare to IPCC predictions? Well, this is one phenomenon among a growing list that is showing worse conditions than the too-careful IPCC folks were willing to give credence to. What do I mean? Look at this graph showing the average and range of September minimum Arctic sea ice extent as projected by models considered by the IPCC. The time series starts in 1900 and runs through 2100. The 20th century projections performed pretty well compared to the observed sea ice extent (denoted by the red line). Sea ice remains as a phenomenon that isn't well understood, so this decent performance is fairly impressive.

But look what happened in the early 21st century (i.e. the last 9 years). The observations fell off to a level that the IPCC models didn't project would be reached until the middle of the century. In other words, the IPCC projections were 40 years too late in projecting the recent record low extents observed in the Arctic!! Note that the models project a gradual decrease in extent down to about 2 million sq. km. by the year 2100. Some glaciologists and climatologists that engage in field activities in the Arctic are now pushing the date at which the minimum plummets below 2 million sq. km., even down to 0-effective extent, all the way back to the next 3-10 years! So not only will most of us witness an ice-free Arctic within our lifetimes (as the IPCC projected 3 years ago), most of use will likely witness an ice-free Arctic within the decade.

You can find the NSIDC's July report here. The page is dynamic, so if you're reading this after July 2010, that month's report will show up first. If that's the case, you can look for the June report on the top pull-down tab on the right-hand side of the page.

Here is a satellite representation of Antarctic sea ice conditions from a couple of days ago (no images from yesterday are yet available):

For comparison purposes, here is the similar picture from June:

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations through yesterday:

Contrary to Arctic sea ice conditions, the Antarctic sea ice extent has undergone a very large increase since mid-March. As the time-series above demonstrates, today's extent is very unusual (outside the +/- 2 standard deviation range). It is impossible to tell how much ice will be present in mid-September when its extent is highest for this year.

Cross-posted at WeatherDem - the blog.

State of the Poles - 6/21/10

WeatherDem — Tue, 22 Jun 2010 17:07:29 GMT

I didn't issue this earlier this month because I was waiting for the NSIDC monthly report, which was issued during a well-deserved vacation. I had originally written most of it to reflect conditions in early June, but apparently forgot to download the necessary graphics to complete the post. As such, I'm updating some of it for conditions through yesterday, which have only grown worse in the Arctic region. I'll issue a similar post in early July to get back on my regular schedule.

The state of polar sea ice in mid-June 2010 is fairly good compared to climatological conditions (1979-2000). The Antarctic sea ice extent is rebounding very nicely from its Southern Hemispheric fall minimum. It has passed the climatological median and is approaching the +2 standard deviation (there is much more ice than is normal for this time of year). The Arctic sea ice extent is a different story altogether, however. Conditions there are the worst on record for June, beating out years such as 2006 and 2007 for record low extent in recent days, as this time series shows.
[Update]: I saw a diary at DailyKos after posting this (still catching up on 2 weeks' worth of news, blogs, etc.) that should be top-headline news, even amongst the items currently in that spot. Arctic ice cap now smallest in at least a few thousand years. It links to a ScienceDaily article with the details: Arctic ice at low point compared to recent geologic history. The key finding is this: the rate of ice loss witnessed in the past 30 years, and that of the past century, is unprecedented over the last few thousand years. The Arctic sea ice sheet has fundamentally changed. Its existence and characteristics in the 21st century will be very different than it was in the last few millenia. President Obama talks a lot about future generations. Is this the future he is prepared to hand them?

Arctic Ice

The big change since last month has been the very rapid melting of ice that is less than one year old. This ice is the thinnest and thus the most susceptible to warmer conditions. In fact, as of the beginning of June 2010, the areal ice extent reached a modern-day record low of ~11.5 million sq. km., which is 1.5 million sq. km. below the climatological average! Unfortunately, ~2 million sq. km. of Arctic sea ice melted in May 2010. How big is that? The country of Mexico is a little smaller than 2 million sq. km. in size. The country of Saudi Arabia is a little larger than 2 million sq. km. in size. Colorado is ~270,000 sq. km. More than 7 Colorado's worth of ice melted in one month's time in the Arctic. When you read or hear that most of the warming already experienced by the Earth has happened near the poles, this is merely one effect. Rapid growth and decay of ice can and will occur. Overall, however, ice volume has decreased. Ice volume has been decreasing for decades. It is only recently that enough volume has melted that the impacts become obvious in the areal extent.

Antarctic Ice

The state of Antarctic sea ice in mid-June 2010 was much better than it was during April 2010 - exceeding the average extent relative to climatological norms by an increasing margin throughout the last month and a half. The areal extent shifted from normal to significantly more than normal during this time. The extent at the middle of June 2010 was larger than at the middle of June 2009. I haven't read anything definitive as to the reason, but given how much Antarctic ice melts and grows each year and taking into consideration the evidence of rapidly decaying and growing Arctic ice, it makes sense that Antarctic sea ice isn't very thick. Nearly all of it melts every year. It appears as though the rate of growth or decline simply shifts annually with given weather conditions.

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Here are my State of Polar Ice posts from May and April.

Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from yesterday:

For comparison purposes, here is the similar picture from May:

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 yesterday:

Obviously, the satellite-derived graphic and the time-series plot show a very large amount of Arctic sea ice melting since the beginning of April. The sea ice extent has been at a modern-day record low since late May.

I was recently made aware of a slightly different Arctic sea ice extent time series - one that shows conditions since 2002. I have found that it provides additional context for comparing current conditions against the past. One of the striking things that came through was the record-setting extent of ice in early April 2010 (red curve; the largest extent occurring at the latest calendar date) shifting to the record-setting extent of ice in early June 2010. While the rapid melting observed so far this year is significant, it doesn't really indicate one way or the other what conditions this fall will be. 2007 (dark green curve) and 2008 (light green curve) witnessed very low extents. Will weather and ice conditions be conducive to repeat that sad state this year? We'll have to wait and see.

You can find the NSIDC's May report here. The page is dynamic, so if you're reading this after June 2010, that month's report will show up first. If that's the case, you can look for the May report on the top pull-down tab on the right-hand side of the page.

Here is a satellite representation of Antarctic sea ice conditions from yesterday:

For comparison purposes, here is the similar picture from May:

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations through yesterday:

Cross-posted at WeatherDem - the blog.

State of the Poles - 5/5/10

WeatherDem — Wed, 05 May 2010 22:41:46 GMT

The state of polar sea ice in March 2010 is fairly good compared to climatological conditions (1979-2000), which strongly contrasts with the past few months when global conditions were below climatology. As it has done this time of year for a few years in a row, the global sea ice extent increased to the point where it is near climatological values, as this graph demonstrates. The anomalies observed in 2006 and 2007 become more obvious each time the globe's sea ice increases in Mar/Apr.
Arctic Ice

The state of Arctic sea ice in April 2010 grew slightly worse from March's near-average conditions. Bering Sea ice extent remained above-average, while the extent in the Barents Sea and Baffin Bay was below average. The areal extent of Arctic sea ice remained just below average conditions for most of the month until weather patterns shifted in the last week and a dramatic melt began. The rapid decrease in extent and openings in the middle of the ice pack point toward the lack of multi-season ice and the prevalence of single-season ice, which melts faster than older ice. As the melt season continues, weather patterns and the lack of multi-season ice will have big effects on the export of ice into the Atlantic Ocean and the rate at which that ice melts.

The Arctic Oscillation that sent so much cold air to the south this winter, and was more strongly negative than any time in the past 50 years, became less intense - to the point that it was characterized as 'neutral' heading into May. The near-surface temperatures in the Arctic region remained above normal (+2 to 3C in most locations, +7 to 9C in the northern Canadian Arctic!!) throughout the month again. A side note here - above normal temperatures doesn't mean above freezing. Abnormally warm conditions in the winter and spring are still below and near freezing.

The average ice extent for April 2010 was 14.69 million sq. km., which was larger than during any April in the past 9 years. That extent was 820,000 sq. km. more than the record low extent set in 2007. Since 1978, the Arctic sea ice extent in April has decreased at 2.6% per decade.

Antarctic Ice

The state of Antarctic sea ice in April 2010 was better than it was during March 2010 - nearly matching the average extent relative to climatological norms. The areal extent shifted from below normal to slightly more than normal during the month. The yearly minimum was reached in early February, and the ice has been steadily growing ever since.

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Here are my State of Polar Ice posts from April and March.

Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from May 4th:

For comparison purposes, here is the similar picture from April:

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 yesterday:

You can find the NSIDC's April report here. The page is dynamic, so if you're reading this after May 2010, that month's report will show up first. If that's the case, you can look for the April report on the top pull-down tab on the right-hand side of the page.

Here is a satellite representation of Antarctic sea ice conditions from yesterday:

For comparison purposes, here is the similar picture from April:

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations through yesterday:

Cross-posted at WeatherDem - the blog.

State of the Poles - 4/7/10

WeatherDem — Wed, 07 Apr 2010 23:51:47 GMT

The state of Arctic sea ice in March 2010 improved significantly from February's below average conditions. Favorable weather conditions set up over the Barents and Bering Seas that helped new ice form along the edges of the ice pack present one month ago. Until the first few days of March, the areal extent of Arctic sea ice was below (-)2 standard deviations since late June 2009. Recent conditions have continued a late cool season surge in sea ice areal extent - culminating in the latest date of the year for the maximum extent to be observed: Mar 31st. It is worth noting that this new ice is very young - ice less than one year old will be the most vulnerable to melting in the next six months. Older ice is more able to withstand the warmer temperatures. This rather obvious characterization will be important when discussing the likely outcome of the upcoming melt season.

During March, the Arctic Oscillation was became less intense. The near-surface temperatures in the Arctic region remained slightly above normal throughout the month, however. A side note here - above normal temperatures doesn't mean above freezing. A couple of prominent climate change deniers idiotically tried to argue in the past month that the warmer than normal temperatures must mean the Arctic was in full melt mode. So outside of the Bering and Barents Sea regions, less ice volume formed than would have been the case if temperatures were cooler.

The average ice extent for February 2010 was 15.1 million sq. km., the sixth lowest since 1978, when satellite records began. That extent was 670,000 sq. km. more than the record low extent set in 2006. It was also a substantial improvement over the February different of 220,000 sq. km. Since 1978, the Arctic sea ice extent in March has decreased at 2.6% per decade.

Antarctic Ice

The state of Antarctic sea ice in March 2010 is slightly below average relative to climatological norms. After a pretty normal February, weather conditions conspired to slow down ice growth in the middle of March. As a result, the areal extent shifted from above normal to almost -2 standard deviations below normal before recovering at the end of the month to be just below normal. The yearly minimum was reached in early February, growing more or less continually ever since.

Ice Thickness

The last item discussed in the NSIDC report is ice thickness. As I stated above, the relative thickness of sea ice is one determining factor into predicting the areal extent of ice in a melt season. The NSIDC report includes plots of different kinds of ice (1st-year, 2nd-year, multi-year), their location at different points in the past year and a time series of the three types. What is important to take away from the last plot is the increasing prevalence of ice that is less than one year old. Back in the 1980s, this ice constituted ~55% of the Arctic ice. In the past decade, that number has increased to 70% of the ice. 2 year and older ice used to make up 30-40% of Arctic ice. In the past 10 years, that has decreased to 20% and a significant drop-off from that value can be see after 2007 - down to 10% or so in the past couple of years.

Ice that is older is also typically thicker. The reasons are obvious: it has more time to add ice vertically instead of horizontally. Snow can fall on it year after year, maintaining the ice's overall integrity. In recent years, that kind of ice has nearly disappeared from the Arctic Ocean. That is important because ice and snow reflect more sunlight back into space than does dark ocean water. As more areas lose their reflective ice covering, they absorb more sunlight and thus warm up more than normal. A warmer Arctic Ocean means ice has a harder time forming even when the sun slips below the horizon for the winter. All that heat has to be moved out of the Arctic into the Atlantic or released back into the atmosphere. Those processes take time, which means the next year's ice has a harder time forming and staying around long enough to thicken so that it survives the following melt season.

Climate scientists fear that the Arctic Ocean could eventually warm up enough so that all the ice melts every summer. New ice will still form in the winter, but it won't last longer than a year or two. Opening up that much area to the sun means a lot more energy that used to be reflected back into space will instead be kept inside our climate system. Warming the Arctic would have severe consequences on nearby land-based ice - it would melt even faster than it is today. If land-based ice (on Greenland, for example) melts, it raises sea-levels, among other effects.

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Here is my State of Polar Ice post from March and January.

Pictures and Graphs

Here is a satellite representation of Arctic sea ice conditions from April 4th (they haven't been updated since then):

For comparison purposes, here is the similar picture from August:

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 Apr 4th:

You can find the NSIDC's March report here. The page is dynamic, so if you're reading this after April 2010, that month's report will show up first. If that's the case, you can look for the March report on the top pull-down tab on the right-hand side of the page.

Here is a satellite representation of Antarctic sea ice conditions from Apr 4th:

Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations through Apr 4th:

Cross-posted at WeatherDem - the blog.