Arctic sea ice at record low for July


Arctic sea ice extent averaged for July 2011 reached the lowest level for the month in the 1979 to 2011 satellite record, even though the pace of ice loss slowed substantially during the last two weeks of July. Shipping routes in the Arctic have less ice than usual for this time of year, and new data indicate that more of the Arctic’s store of its oldest ice disappeared.

From the National Snow and Ice Data Center (NSIDC): July 2011 compared to previous years
Average Arctic sea ice extent for July 2011 was the lowest for July in the satellite data record. The previous lowest year for July was 2007, which went to break the record for the lowest ice extent at the end of the melt season. Including 2011 the linear trend for July now stands at -6.8% per decade.

July 2011 compared to previous years

Monthly July ice extent for 1979 to 2011 shows a decline of 6.8% per decade. —Credit: National Snow and Ice Data Center

Figure 6 shows the daily change in extent (averaged over the prior week) and figure 7 compares the recent extents as a percentage of the 2003 – 2010 extent for the same day of the year. The data for this analysis were downloaded from “IJIS” (the IARC-JAXA Information System) reporting the AMSR-E sea ice extent on a daily basis since 2002.

As of Aug. 24, unless the Arctic weather changes dramatically over this next 4 weeks or or so, given the visible trend shown in figure 6 there is a very good chance that the minimum extent for 2011 will be lower than the previous record in 2007.

Ice Fig. 5. Measured Extent

Ice Fig. 5. Measured Extent

Ice Fig. 6. Average Daily Change

Ice Fig. 6. Average Daily Change

Ice Fig. 7. Extent as a Percent of the Average Since 2003

Ice Fig. 7. Extent as a Percent of the Average Since 2003

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