Sea ice in the Arctic continues to track significantly below average, with the 3rd lowest readings for the month in the modern era. Antarctic sea ice recovered somewhat more quickly to normal conditions than was the case the month before. Global sea ice area has therefore remained near historical lows for an extended period of time this year. Within the last month, global sea ice area has finally improved from the 1 million sq. km. deficit from climatological conditions that characterized the first four months of 2011. To help put this in context, only 2006 and 2007 saw similar conditions. In 2007, the Arctic (and global) sea ice area fell to its lowest extent in modern history.
Portions of the Arctic are warmer places in 2011 than at the same point in 2007. Warmer water than in past years continues to be transported into the Arctic Ocean at rates that are quickening (more warm water faster – not a good thing for ice survivability). Weather conditions (local pressure centers, resulting wind patterns, etc.) will have the final influence on what conditions in Sep. 2011 look like. Updating my guess from last month, I don’t think 2011 will challenge the record low extent of 2007. I think it is likely that Arctic ice extent will end up in the lowest 3 extents on record.
According to the National Snow and Ice Data Center, Arctic sea ice extent in May was the 3rd lowest on record. Averaged over May 2011, Arctic sea ice extent was only 12.79 million sq. km. Arctic ice in May almost matched the rate of decrease recorded in May 2010, which was the fastest in the past decade.
The change in May ice extent has been measured at -2.4% per decade by the NSIDC. What that means is as of the end of May 1978, the Arctic had 14 million sq. km. of sea ice while May 2011′s extent was, as stated above, only 12.79 million sq. km. After posting record low extent values in 2004 and 2006, the past Mays saw a rebound in extent values. The past three Aprils looked more like the extents of the 1990s. Alas, 2011 looks a lot more like 2004 than 2010.
Arctic Pictures and Graphs
The following graphic is a satellite representation of Arctic ice as of June 6, 2001:
Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110606.
Compare this with May 4th’s satellite representation, also centered on the North Pole:
Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110504.
While the central Arctic showed thinning ice in early May, weather conditions the rest of the month didn’t allow for the region to melt quite yet. Instead, areas at the periphery of the ice pack melted, especially near the Atlantic where ice formation during the Arctic winter took longer than usual. 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.
Arctic sea ice volume is in terrible condition and it is once again worsening. This means the areas that had sea ice this year have thinner sea ice than they did last year or ten years ago. This thinning helps lead to the record low areal extents that have been recorded in recent years.
Here is a time series of Arctic sea ice extent through yesterday:
Figure 4 – NSIDC Arctic sea ice extent time series.
You can see that the 2011 time series line edged beneath the extent set in 2007. Similar graphs comparing multiple years show that 2011′s extent is at or near the record low extent during the satellite record. The graph also shows that we will know if 2011 will challenge the all-time record low extent of September 2007 or not sometime in late June or early July.
Antarctic Pictures and Graphs
Here is a satellite representation of Antarctic sea ice conditions from June 6th:
Figure 5 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20110606.
Compare that with the similar graphic of conditions on May 4th:
Figure 6 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20110504.
New sea ice continues to form along the edges of the ice mass from the past few months. This process occurred at a more rapid than normal rate during the past month. The extent has only reached normal values in the past couple of weeks, as the following time series graph shows:
Figure 7 – NSIDC Arctic sea ice extent time series.
This graph shows that ice has formed at a somewhat faster than average rate in the past month. The difference between conditions at the beginning of May and the end of May reflects a continuation of relatively healthy processes.
You can find the NSIDC’s May report here.
Cross-posted at SquareState.