Where Did All the Ice Go? A Closer Look at the 2012 Melting Season

By Malte Humpert The 2012 melting season is in full swing and as of August 14 ice extent continues to track below the level for same date during the record melt year of 2007. This year's ice extent may be on track to reach a new record low in September. The graph below shows ice extent on August 14 for the 1980s, 1990s, 2000s, and 2002-2012.
According to Mark Serreze, director of the National Snow and Ice Data Center (NSIDC), ice loss is on pace to set a new record this year. Data sets by the NSIDC and the Japan Aerospace Exploration Agency (JAXA) show ice extent at 4.9 million square kilometers (August 13) and 5.02 million square kilometer (August 15), about 450,000 square kilometers below the 2007 record low for this date. The University of Bremen, whose data do not take into account ice along a 30km coastal zone, already sees ice extent below the all-time record low of 2007.

The interactive graph below place ice loss into a historical context and displays ice extent (at least 15% ice coverage) for the 1980s, 1990s, 2000s and 2007-2012. The graph is based on data by JAXA which can be found here.
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A closer look at ice extent over the past month/14 days reveals how decline has accelerated since August 5 when a low pressure system entered the Arctic Ocean. The most rapid melt was observed on August 5-8 when ice extent dropped by more than 500,000 square kilometers.

The rate of decline between July 15 and August 14 reached 34.59%. In comparison during the 1980s and 90s ice extent decreased by only 20% in that 30 day period. During the record year of 2007 ice extent shrank by 30% between those two dates.

In addition to ice extent, ice volume is an important indicator. Volume relates to both ice thickness and extent and is therefore more directly tied to the long-term trends of climate change and less susceptible to particular weather patterns, i.e. storms or shift in winds that can affect ice extent. Ice volume on July 31, 2012, the last day for which PIOMAS data by the Polar Science Center at the University of Washington is available, stood at 5,770 cubic kilometers, compared to 12,433 cubic kilometers during the 2000s and 6,494 cubic kilometers in 2011.
The interactive graph below depicts ice volume for the 1980s, 1990s, 200s and 2007-2012. The graph is based on data by PIOMAS. Ice volume has declined dramatically over the past decade. The 2011 minimum ice volume was more than 50 percent below the minimum ice volume of 2005. Even in comparison to the record low ice extent year of 2007, ice volume decreased by almost 40 percent. The ice extent in 2007 and 2011 was roughly the same with 4.3 and 4.61 million square km, while ice volume decreased from 6.53 to 4.2 thousand cubic km showing how ice volume is decreasing at a much more rapid pace than ice extent. The ice volume for July 31, 2012 was roughly 10% below the value for the same day in 2011. A new study by UK scientists confirms that ice volume is declining at a remarkable rate of up to 900 cubic kilometers per year since 2004.

The rate of ice volume decline for the month of July reached a new record at 47%. This compares to 33% during the 2000s.
The final graph displays ice volume and ice extent for July 31 for the 1980s, 1990s, 2000s and 2002-2012 and shows how much faster ice volume is declining in comparison to ice extent. Whatever ice remained at the end of the summer 2011 was on average ~60% thinner than the ice during the 2000s.
* no data available for 2002 ice exent

[1] Chart based on data from Japan Aerospace Exploration Agency (JAXA) Sea Ice extent Data through the IARC-JAXA Information System (IJIS). Data accessed on 07/30/2012 at http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
[2] Charts based on data from PIOMAS Daily Ice Volume Data. Schweiger, A. 2011. Arctic Sea Ice Volume Anomaly, Version 2. Seattle, WA: Polar Science Center, Applied Physics Laboratory, University of Washington. Data set accessed on 12/20/2011 at http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/.