The state of global polar sea ice area in early August 2011 continues to fare poorly: well below climatological conditions (1979-2009) persist, as they have for every month so far this year.
Sea ice in the Arctic continues to track significantly below average, between the second worst and worst readings during July (depending on the day) in the modern era. Weather conditions around Antarctica returned to normal during July, recovering from a temporary stall in freezing that occurred during June. Global sea ice area therefore tracked well below normal during July, reaching for historical lows reached only three times before now. During July, global sea ice area hovered near the negative 2 million sq. km. anomaly mark. To date, this is the longest stretch of time that such a negative anomaly has stayed near 2 million sq. km.
To help put this in context, only three previous times in recent history have seen conditions as bad as they are today: in 2007, 2008 and 2010. The difference between these previous occurrences and current conditions is profound: they previously occurred around September, when Arctic ice reached its annual minima. Will a new record low global sea ice area be recorded this year? Stay tuned. There is only one more month of melting to go in the Northern Hemisphere, while the Southern Hemisphere’s freezing rate will slow down.
Portions of the Arctic are experiencing warmer near-surface conditions in 2011 than at the same point in 2007, when the record low extent of sea ice was recorded. Additionally, warmer water than in past years continues to be transported into the Arctic Ocean at rates that are quickening (more warm water flowing through the Ocean faster – not a good thing for long-term ice survivability). Weather conditions (local pressure centers, resulting wind patterns, etc.) will have the final influence on what conditions in Sep. 2011 look like. During this summer, the dipole anomaly was again established, though it has weakened somewhat in the past month or so. Prior to the late 1990s, this atmospheric phenomenon didn’t occur – as in at all. It is postulated that the dipole is setting up in response to climate change. Updating my guess from last month, I think that 2011 still might challenge 2007 for setting the record low extent. If the record isn’t set this this, I don’t think the miss will be by much.
According to the National Snow and Ice Data Center, Arctic sea ice extent in July was the 3rd lowest on record. Averaged over July 2011, Arctic sea ice extent was only 7.92 million sq. km. According to the NSIDC, “Ice extent during July 2011 declined at an average rate of 90,200 square kilometers (34,800 square miles) per day. Ice loss slowed towards the end of July as a high-pressure cell centered over the northern Beaufort Sea broke down and a series of low-pressure systems moved over the central Arctic Ocean. This change brought cooler conditions and likely pushed the ice apart into a thinner but more extensive ice cover.″.
The change in July ice extent has been measured at -6.8% per decade by the NSIDC. What that means is as of the end of July 1978, the Arctic had 10.5 million sq. km. of sea ice while July 2011′s extent was, as stated above, only 7.92 million sq. km. After posting a record low extent value in 2007, the following few Julys saw a relative rebound in extent values. That did not happen this year, as I thought it wouldn’t. Overall, it’s the trend that is important. It will take monumental effort to turn around a 6.8% decadal decline in ice extent. Of course, that value will soon be reduced to near zero as there won’t be much sea ice in any summer, thus negating the influence of such a trend observation.
Arctic Pictures and Graphs
The following graphic is a satellite representation of Arctic ice as of August 7, 2011:
Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110807.
Compare this with July 13th’s satellite representation, also centered on the North Pole:
Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110713.
In the past few weeks, a considerable amount of ice at the periphery of the ice pack has melted away, especially around the Canadian Archipeligo and Arctic Ocean north of Canada and Alaska. So much ice has melted around the Archipeligo islands that the Northwest Passage is almost open. You should also note that the Northeast Passage is open again in 2011.
Overall, the health of the remaining ice pack is not healthy, as the following graph of Arctic ice volume from the end of the month demonstrates:
You might notice a slight uptick in the volume anomaly at the far right end of the time series. As of the end of the month, the volume anomaly was not at a record low value, but the record was set just a handful of days ago. Just as the monthly extent time series show negative trends over the past few decades, the volume time series shows a significant decrease over the past 30+ years. It is this decrease which has helped years like 2007 and 2010 witness extremely low areal extent values. This volume graph basically ensures that new record lows will be set in future years.
Moving from volume to areal extent, take a look at this month’s time series graph through the 4th of July (prepared for the NSIDC report) which compares 2011 conditions to those in 2007, 2008, and 2010:
Figure 4 – NSIDC Arctic sea ice extent time series.
Thanks to the shift in weather conditions in the 2nd half of July, 2011’s extent edged to higher values than those recorded in 2007 when the dipole was maintained throughout the summer. As of a few days ago, 2011’s extent matched 2010’s. It will be this set of years with which 2011 will compete for among the lowest minimum value in a little over a month. This graph and the volume anomaly graph demonstrate the problem the Arctic faces in upcoming years: melt rates will not have to be as high in the future in order to achieve the same low areal and volume values.
Antarctic Pictures and Graphs
Here is a satellite representation of Antarctic sea ice conditions from August 7th:
Figure 5 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20110807.
Compare that with the similar graphic of conditions on July 13th:
Figure 6 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110713.
Ice formation is evident on the opposite side of Antarctica from the Peninsula, although freezing obviously occurred near the tip of the Peninsula also. This process occurred faster in July than it did in June, likely due to local weather patterns that kept forming ice pinned up against the existing ice sheet. This becomes clear when looking at the Antarctic sea ice extent time series:
Figure 7 – NSIDC Antarctic sea ice extent time series.
The difference between 2010 and 2011 is rather striking in this graph. Conditions from the two paralleled each other earlier this year before diverging in June and early July. While 2010 saw very rapid ice formation continue throughout the Southern Hemispheric winter, 2011 hasn’t seen similar formation rates. Nothing extreme like collapsing ice shelves happened around Antarctica in the past month. Indeed, there have been no reports of ice sheet collapse this year. The ice formation season for Antarctica is winding down. In 5-6 weeks, increasing amounts of solar radiation will begin the process of melting Antarctic sea ice. There is nothing that would indicate that this year’s maximum extent will be significantly different from average.
You can find the NSIDC’s July report here.