Sea ice in the Arctic continues to track significantly below average, with the 2nd to lowest readings for the month (depending on the day) in the modern era. Weather conditions around Antarctica caused a temporary stall in sea ice freezing, causing extent conditions to tack toward below average conditions before recently recovering somewhat. Global sea ice area therefore took a turn for the worse during June and early July, reaching for historical lows reached only a couple of times before now. Within the last month, global sea ice area reversed the gains made in May toward eliminating the deficit from climatological conditions that characterized the first four months of 2011 and has instead declined rapidly to a 2 million sq. km. deficit by early July.
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. This, of course, is July. There are over two months left before melting in the Arctic stops. Will a new record low sea ice area be recorded this year? Stay tuned.
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. As this summer has progressed, the dipole anomaly has again been established. Prior to the late 1990s, this atmospheric phenomenon didn’t occur. It is postulated that it is setting up in response to climate change. Updating my guess from last month, I think 2011 might challenge 2007 for setting the record low extent. The extent is hovering at daily record low values and the dipole has set up again. It will only take a couple of storm systems to prevent 2011 from setting the record low, however. But I don’t think it will miss it by much.
According to the National Snow and Ice Data Center, Arctic sea ice extent in May was the 3rd lowest on record. Averaged over June 2011, Arctic sea ice extent was only 11.01 million sq. km. According to the NSIDC, “Ice extent during June 2011 declined at an average rate of 80,800 square kilometers (31,200 square miles) per day, about 50% faster than the average decline rate for June 1979 to 2000. Ice extent declined more slowly than in June 2010, the year with the lowest average ice extent for the month. However, ice declined faster than in June 2007”.
The change in June ice extent has been measured at -3.6% per decade by the NSIDC. What that means is as of the end of June 1978, the Arctic had 12.5 million sq. km. of sea ice while June 2011?s extent was, as stated above, only 11.01 million sq. km. After posting a record low extent value in 2006, the following few Junes saw a rebound in extent values. Then, the extent fell to a new record low in 2010. Since the extent declined at a slower rate this year than last, the record low of 2010 holds for another year. I don’t expect the same to hold for July.
Arctic Pictures and Graphs
The following graphic is a satellite representation of Arctic ice as of July 13, 2001:
Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110713.
Compare this with June 6th’s satellite representation, also centered on the North Pole:
Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110606.
In the past month or so, a considerable amount of ice at the periphery of the ice pack has melted away. The Hudson Bay and area west of Greenland are currently devoid of ice. Areas north of western Russia and Siberia are likewise ice free this month. And finally, the area north of Alaska and Canada is showing rapid melt currently underway.
Overall, the health of the remaining ice pack is not healthy, as the following graph of Arctic ice volume demonstrates:
Figure 3 – PIOMAS Arctic sea ice volume time series.
The decline from negative 7,000 km^3 to nearly -10,000 km^3 has occurred in just the past month. A new record low volume has been set again. The previous record low? It occurred in September of 2010. As I said above, there are two months remaining in this year’s melt season. It doesn’t seem likely that the volume will recover in that time frame – barring significant weather patterns that prevent continued melting.
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 and 2010:
Figure 4 – NSIDC Arctic sea ice extent time series.
As you can see, 2011’s extent was well below 2007’s for much of June and hovered near 2010’s record low extent. In the early part of 2010, weather conditions allowed ice melt to slow for a short time before the rate of melting increased. That prevented 2010 from achieving record low extent values by the time September came around. The time series line for 2011 has continued to track below 2007’s as of yesterday. These graphs also present an interesting point: melt in this year and future years won’t need to be as rapid in order to achieve very low extent values. With less volume of ice present, less heating will be necessary to achieve the same amount of areal extent. Of course, the amount of heating won’t decrease any time soon. Instead, it will continue to increase and impact an ice sheet that has less and less volume available to melt. Thus the predictions of an effective ice-free Arctic Ocean at the end of melt season in the next 10 years.
Antarctic Pictures and Graphs
Here is a satellite representation of Antarctic sea ice conditions from July 13th:
Figure 5 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20110713.
Compare that with the similar graphic of conditions on June 6th:
Figure 6 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110606.
New sea ice continues to form along the edges of the ice mass that formed over the past few months. This process slowed down somewhat during June, after some of the fastest freezing occurred in May. After reaching average extent values in May, the extent fell below average in June and has recently rebounded:
Figure 7 – NSIDC Arctic sea ice extent time series.
The difference between 2010 and 2011 is rather striking in this graph. Conditions paralleled each other earlier this year before diverging in June. Nothing extreme happened around Antarctica in the past month. Thankfully, there have been no reports of collapses of ice sheets this year.
You can find the NSIDC’s May report here.